1/*
2 * Copyright (c) 2012-2013, 2018 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2003-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Erik Hallnor
41 * Nikos Nikoleris
42 */
43
44/**
45 * @file
46 * Definition of BaseCache functions.
47 */
48
49#include "mem/cache/base.hh"
50
51#include "base/compiler.hh"
52#include "base/logging.hh"
53#include "debug/Cache.hh"
54#include "debug/CachePort.hh"
55#include "debug/CacheRepl.hh"
56#include "debug/CacheVerbose.hh"
57#include "mem/cache/mshr.hh"
58#include "mem/cache/prefetch/base.hh"
59#include "mem/cache/queue_entry.hh"
60#include "params/BaseCache.hh"
61#include "params/WriteAllocator.hh"
62#include "sim/core.hh"
63
64class BaseMasterPort;
65class BaseSlavePort;
66
67using namespace std;
68
69BaseCache::CacheSlavePort::CacheSlavePort(const std::string &_name,
70 BaseCache *_cache,
71 const std::string &_label)
72 : QueuedSlavePort(_name, _cache, queue), queue(*_cache, *this, _label),
73 blocked(false), mustSendRetry(false),
74 sendRetryEvent([this]{ processSendRetry(); }, _name)
75{
76}
77
78BaseCache::BaseCache(const BaseCacheParams *p, unsigned blk_size)
79 : MemObject(p),
80 cpuSidePort (p->name + ".cpu_side", this, "CpuSidePort"),
81 memSidePort(p->name + ".mem_side", this, "MemSidePort"),
82 mshrQueue("MSHRs", p->mshrs, 0, p->demand_mshr_reserve), // see below
83 writeBuffer("write buffer", p->write_buffers, p->mshrs), // see below
84 tags(p->tags),
85 prefetcher(p->prefetcher),
86 prefetchOnAccess(p->prefetch_on_access),
87 writeAllocator(p->write_allocator),
88 writebackClean(p->writeback_clean),
89 tempBlockWriteback(nullptr),
90 writebackTempBlockAtomicEvent([this]{ writebackTempBlockAtomic(); },
91 name(), false,
92 EventBase::Delayed_Writeback_Pri),
93 blkSize(blk_size),
94 lookupLatency(p->tag_latency),
95 dataLatency(p->data_latency),
96 forwardLatency(p->tag_latency),
97 fillLatency(p->data_latency),
98 responseLatency(p->response_latency),
99 numTarget(p->tgts_per_mshr),
100 forwardSnoops(true),
101 clusivity(p->clusivity),
102 isReadOnly(p->is_read_only),
103 blocked(0),
104 order(0),
105 noTargetMSHR(nullptr),
106 missCount(p->max_miss_count),
107 addrRanges(p->addr_ranges.begin(), p->addr_ranges.end()),
108 system(p->system)
109{
110 // the MSHR queue has no reserve entries as we check the MSHR
111 // queue on every single allocation, whereas the write queue has
112 // as many reserve entries as we have MSHRs, since every MSHR may
113 // eventually require a writeback, and we do not check the write
114 // buffer before committing to an MSHR
115
116 // forward snoops is overridden in init() once we can query
117 // whether the connected master is actually snooping or not
118
119 tempBlock = new TempCacheBlk(blkSize);
120
121 tags->init(this);
122 if (prefetcher)
123 prefetcher->setCache(this);
124}
125
126BaseCache::~BaseCache()
127{
128 delete tempBlock;
129}
130
131void
132BaseCache::CacheSlavePort::setBlocked()
133{
134 assert(!blocked);
135 DPRINTF(CachePort, "Port is blocking new requests\n");
136 blocked = true;
137 // if we already scheduled a retry in this cycle, but it has not yet
138 // happened, cancel it
139 if (sendRetryEvent.scheduled()) {
140 owner.deschedule(sendRetryEvent);
141 DPRINTF(CachePort, "Port descheduled retry\n");
142 mustSendRetry = true;
143 }
144}
145
146void
147BaseCache::CacheSlavePort::clearBlocked()
148{
149 assert(blocked);
150 DPRINTF(CachePort, "Port is accepting new requests\n");
151 blocked = false;
152 if (mustSendRetry) {
153 // @TODO: need to find a better time (next cycle?)
154 owner.schedule(sendRetryEvent, curTick() + 1);
155 }
156}
157
158void
159BaseCache::CacheSlavePort::processSendRetry()
160{
161 DPRINTF(CachePort, "Port is sending retry\n");
162
163 // reset the flag and call retry
164 mustSendRetry = false;
165 sendRetryReq();
166}
167
168Addr
169BaseCache::regenerateBlkAddr(CacheBlk* blk)
170{
171 if (blk != tempBlock) {
172 return tags->regenerateBlkAddr(blk);
173 } else {
174 return tempBlock->getAddr();
175 }
176}
177
178void
179BaseCache::init()
180{
181 if (!cpuSidePort.isConnected() || !memSidePort.isConnected())
182 fatal("Cache ports on %s are not connected\n", name());
183 cpuSidePort.sendRangeChange();
184 forwardSnoops = cpuSidePort.isSnooping();
185}
186
187BaseMasterPort &
188BaseCache::getMasterPort(const std::string &if_name, PortID idx)
189{
190 if (if_name == "mem_side") {
191 return memSidePort;
192 } else {
193 return MemObject::getMasterPort(if_name, idx);
194 }
195}
196
197BaseSlavePort &
198BaseCache::getSlavePort(const std::string &if_name, PortID idx)
199{
200 if (if_name == "cpu_side") {
201 return cpuSidePort;
202 } else {
203 return MemObject::getSlavePort(if_name, idx);
204 }
205}
206
207bool
208BaseCache::inRange(Addr addr) const
209{
210 for (const auto& r : addrRanges) {
211 if (r.contains(addr)) {
212 return true;
213 }
214 }
215 return false;
216}
217
218void
219BaseCache::handleTimingReqHit(PacketPtr pkt, CacheBlk *blk, Tick request_time)
220{
221 if (pkt->needsResponse()) {
222 pkt->makeTimingResponse();
223 // @todo: Make someone pay for this
224 pkt->headerDelay = pkt->payloadDelay = 0;
225
226 // In this case we are considering request_time that takes
227 // into account the delay of the xbar, if any, and just
228 // lat, neglecting responseLatency, modelling hit latency
229 // just as lookupLatency or or the value of lat overriden
230 // by access(), that calls accessBlock() function.
231 cpuSidePort.schedTimingResp(pkt, request_time, true);
232 } else {
233 DPRINTF(Cache, "%s satisfied %s, no response needed\n", __func__,
234 pkt->print());
235
236 // queue the packet for deletion, as the sending cache is
237 // still relying on it; if the block is found in access(),
238 // CleanEvict and Writeback messages will be deleted
239 // here as well
240 pendingDelete.reset(pkt);
241 }
242}
243
244void
245BaseCache::handleTimingReqMiss(PacketPtr pkt, MSHR *mshr, CacheBlk *blk,
246 Tick forward_time, Tick request_time)
247{
248 if (writeAllocator &&
249 pkt && pkt->isWrite() && !pkt->req->isUncacheable()) {
250 writeAllocator->updateMode(pkt->getAddr(), pkt->getSize(),
251 pkt->getBlockAddr(blkSize));
252 }
253
254 if (mshr) {
255 /// MSHR hit
256 /// @note writebacks will be checked in getNextMSHR()
257 /// for any conflicting requests to the same block
258
259 //@todo remove hw_pf here
260
261 // Coalesce unless it was a software prefetch (see above).
262 if (pkt) {
263 assert(!pkt->isWriteback());
264 // CleanEvicts corresponding to blocks which have
265 // outstanding requests in MSHRs are simply sunk here
266 if (pkt->cmd == MemCmd::CleanEvict) {
267 pendingDelete.reset(pkt);
268 } else if (pkt->cmd == MemCmd::WriteClean) {
269 // A WriteClean should never coalesce with any
270 // outstanding cache maintenance requests.
271
272 // We use forward_time here because there is an
273 // uncached memory write, forwarded to WriteBuffer.
274 allocateWriteBuffer(pkt, forward_time);
275 } else {
276 DPRINTF(Cache, "%s coalescing MSHR for %s\n", __func__,
277 pkt->print());
278
279 assert(pkt->req->masterId() < system->maxMasters());
280 mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
281
282 // We use forward_time here because it is the same
283 // considering new targets. We have multiple
284 // requests for the same address here. It
285 // specifies the latency to allocate an internal
286 // buffer and to schedule an event to the queued
287 // port and also takes into account the additional
288 // delay of the xbar.
289 mshr->allocateTarget(pkt, forward_time, order++,
290 allocOnFill(pkt->cmd));
291 if (mshr->getNumTargets() == numTarget) {
292 noTargetMSHR = mshr;
293 setBlocked(Blocked_NoTargets);
294 // need to be careful with this... if this mshr isn't
295 // ready yet (i.e. time > curTick()), we don't want to
296 // move it ahead of mshrs that are ready
297 // mshrQueue.moveToFront(mshr);
298 }
299 }
300 }
301 } else {
302 // no MSHR
303 assert(pkt->req->masterId() < system->maxMasters());
304 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
305
306 if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean) {
307 // We use forward_time here because there is an
308 // writeback or writeclean, forwarded to WriteBuffer.
309 allocateWriteBuffer(pkt, forward_time);
310 } else {
311 if (blk && blk->isValid()) {
312 // If we have a write miss to a valid block, we
313 // need to mark the block non-readable. Otherwise
314 // if we allow reads while there's an outstanding
315 // write miss, the read could return stale data
316 // out of the cache block... a more aggressive
317 // system could detect the overlap (if any) and
318 // forward data out of the MSHRs, but we don't do
319 // that yet. Note that we do need to leave the
320 // block valid so that it stays in the cache, in
321 // case we get an upgrade response (and hence no
322 // new data) when the write miss completes.
323 // As long as CPUs do proper store/load forwarding
324 // internally, and have a sufficiently weak memory
325 // model, this is probably unnecessary, but at some
326 // point it must have seemed like we needed it...
327 assert((pkt->needsWritable() && !blk->isWritable()) ||
328 pkt->req->isCacheMaintenance());
329 blk->status &= ~BlkReadable;
330 }
331 // Here we are using forward_time, modelling the latency of
332 // a miss (outbound) just as forwardLatency, neglecting the
333 // lookupLatency component.
334 allocateMissBuffer(pkt, forward_time);
335 }
336 }
337}
338
339void
340BaseCache::recvTimingReq(PacketPtr pkt)
341{
342 // anything that is merely forwarded pays for the forward latency and
343 // the delay provided by the crossbar
344 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
345
346 // We use lookupLatency here because it is used to specify the latency
347 // to access.
348 Cycles lat = lookupLatency;
349 CacheBlk *blk = nullptr;
350 bool satisfied = false;
351 {
352 PacketList writebacks;
353 // Note that lat is passed by reference here. The function
354 // access() calls accessBlock() which can modify lat value.
355 satisfied = access(pkt, blk, lat, writebacks);
356
357 // copy writebacks to write buffer here to ensure they logically
358 // precede anything happening below
359 doWritebacks(writebacks, forward_time);
360 }
361
362 // Here we charge the headerDelay that takes into account the latencies
363 // of the bus, if the packet comes from it.
364 // The latency charged it is just lat that is the value of lookupLatency
365 // modified by access() function, or if not just lookupLatency.
366 // In case of a hit we are neglecting response latency.
367 // In case of a miss we are neglecting forward latency.
368 Tick request_time = clockEdge(lat) + pkt->headerDelay;
369 // Here we reset the timing of the packet.
370 pkt->headerDelay = pkt->payloadDelay = 0;
371 // track time of availability of next prefetch, if any
372 Tick next_pf_time = MaxTick;
373
374 if (satisfied) {
375 // if need to notify the prefetcher we have to do it before
376 // anything else as later handleTimingReqHit might turn the
377 // packet in a response
378 if (prefetcher &&
379 (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
380 if (blk)
381 blk->status &= ~BlkHWPrefetched;
382
383 // Don't notify on SWPrefetch
384 if (!pkt->cmd.isSWPrefetch()) {
385 assert(!pkt->req->isCacheMaintenance());
386 next_pf_time = prefetcher->notify(pkt);
387 }
388 }
389
390 handleTimingReqHit(pkt, blk, request_time);
391 } else {
392 handleTimingReqMiss(pkt, blk, forward_time, request_time);
393
394 // We should call the prefetcher reguardless if the request is
395 // satisfied or not, reguardless if the request is in the MSHR
396 // or not. The request could be a ReadReq hit, but still not
397 // satisfied (potentially because of a prior write to the same
398 // cache line. So, even when not satisfied, there is an MSHR
399 // already allocated for this, we need to let the prefetcher
400 // know about the request
401
402 // Don't notify prefetcher on SWPrefetch, cache maintenance
403 // operations or for writes that we are coaslescing.
404 if (prefetcher && pkt &&
405 !pkt->cmd.isSWPrefetch() &&
406 !pkt->req->isCacheMaintenance() &&
407 !(writeAllocator && writeAllocator->coalesce() &&
408 pkt->isWrite())) {
409 next_pf_time = prefetcher->notify(pkt);
410 }
411 }
412
413 if (next_pf_time != MaxTick) {
414 schedMemSideSendEvent(next_pf_time);
415 }
416}
417
418void
419BaseCache::handleUncacheableWriteResp(PacketPtr pkt)
420{
421 Tick completion_time = clockEdge(responseLatency) +
422 pkt->headerDelay + pkt->payloadDelay;
423
424 // Reset the bus additional time as it is now accounted for
425 pkt->headerDelay = pkt->payloadDelay = 0;
426
427 cpuSidePort.schedTimingResp(pkt, completion_time, true);
428}
429
430void
431BaseCache::recvTimingResp(PacketPtr pkt)
432{
433 assert(pkt->isResponse());
434
435 // all header delay should be paid for by the crossbar, unless
436 // this is a prefetch response from above
437 panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
438 "%s saw a non-zero packet delay\n", name());
439
440 const bool is_error = pkt->isError();
441
442 if (is_error) {
443 DPRINTF(Cache, "%s: Cache received %s with error\n", __func__,
444 pkt->print());
445 }
446
447 DPRINTF(Cache, "%s: Handling response %s\n", __func__,
448 pkt->print());
449
450 // if this is a write, we should be looking at an uncacheable
451 // write
452 if (pkt->isWrite()) {
453 assert(pkt->req->isUncacheable());
454 handleUncacheableWriteResp(pkt);
455 return;
456 }
457
458 // we have dealt with any (uncacheable) writes above, from here on
459 // we know we are dealing with an MSHR due to a miss or a prefetch
460 MSHR *mshr = dynamic_cast<MSHR*>(pkt->popSenderState());
461 assert(mshr);
462
463 if (mshr == noTargetMSHR) {
464 // we always clear at least one target
465 clearBlocked(Blocked_NoTargets);
466 noTargetMSHR = nullptr;
467 }
468
469 // Initial target is used just for stats
470 MSHR::Target *initial_tgt = mshr->getTarget();
471 int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
472 Tick miss_latency = curTick() - initial_tgt->recvTime;
473
474 if (pkt->req->isUncacheable()) {
475 assert(pkt->req->masterId() < system->maxMasters());
476 mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
477 miss_latency;
478 } else {
479 assert(pkt->req->masterId() < system->maxMasters());
480 mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
481 miss_latency;
482 }
483
484 PacketList writebacks;
485
486 bool is_fill = !mshr->isForward &&
487 (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp ||
488 mshr->wasWholeLineWrite);
489
490 // make sure that if the mshr was due to a whole line write then
491 // the response is an invalidation
492 assert(!mshr->wasWholeLineWrite || pkt->isInvalidate());
493
494 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
495
496 if (is_fill && !is_error) {
497 DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
498 pkt->getAddr());
499
500 const bool allocate = (writeAllocator && mshr->wasWholeLineWrite) ?
501 writeAllocator->allocate() : mshr->allocOnFill();
502 blk = handleFill(pkt, blk, writebacks, allocate);
503 assert(blk != nullptr);
504 }
505
506 if (blk && blk->isValid() && pkt->isClean() && !pkt->isInvalidate()) {
507 // The block was marked not readable while there was a pending
508 // cache maintenance operation, restore its flag.
509 blk->status |= BlkReadable;
510
511 // This was a cache clean operation (without invalidate)
512 // and we have a copy of the block already. Since there
513 // is no invalidation, we can promote targets that don't
514 // require a writable copy
515 mshr->promoteReadable();
516 }
517
518 if (blk && blk->isWritable() && !pkt->req->isCacheInvalidate()) {
519 // If at this point the referenced block is writable and the
520 // response is not a cache invalidate, we promote targets that
521 // were deferred as we couldn't guarrantee a writable copy
522 mshr->promoteWritable();
523 }
524
525 serviceMSHRTargets(mshr, pkt, blk, writebacks);
526
527 if (mshr->promoteDeferredTargets()) {
528 // avoid later read getting stale data while write miss is
529 // outstanding.. see comment in timingAccess()
530 if (blk) {
531 blk->status &= ~BlkReadable;
532 }
533 mshrQueue.markPending(mshr);
534 schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
535 } else {
536 // while we deallocate an mshr from the queue we still have to
537 // check the isFull condition before and after as we might
538 // have been using the reserved entries already
539 const bool was_full = mshrQueue.isFull();
540 mshrQueue.deallocate(mshr);
541 if (was_full && !mshrQueue.isFull()) {
542 clearBlocked(Blocked_NoMSHRs);
543 }
544
545 // Request the bus for a prefetch if this deallocation freed enough
546 // MSHRs for a prefetch to take place
547 if (prefetcher && mshrQueue.canPrefetch()) {
548 Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
549 clockEdge());
550 if (next_pf_time != MaxTick)
551 schedMemSideSendEvent(next_pf_time);
552 }
553 }
554
555 // if we used temp block, check to see if its valid and then clear it out
556 if (blk == tempBlock && tempBlock->isValid()) {
557 evictBlock(blk, writebacks);
558 }
559
560 const Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
561 // copy writebacks to write buffer
562 doWritebacks(writebacks, forward_time);
563
564 DPRINTF(CacheVerbose, "%s: Leaving with %s\n", __func__, pkt->print());
565 delete pkt;
566}
567
568
569Tick
570BaseCache::recvAtomic(PacketPtr pkt)
571{
572 // We are in atomic mode so we pay just for lookupLatency here.
573 Cycles lat = lookupLatency;
574
575 // follow the same flow as in recvTimingReq, and check if a cache
576 // above us is responding
577 if (pkt->cacheResponding() && !pkt->isClean()) {
578 assert(!pkt->req->isCacheInvalidate());
579 DPRINTF(Cache, "Cache above responding to %s: not responding\n",
580 pkt->print());
581
582 // if a cache is responding, and it had the line in Owned
583 // rather than Modified state, we need to invalidate any
584 // copies that are not on the same path to memory
585 assert(pkt->needsWritable() && !pkt->responderHadWritable());
586 lat += ticksToCycles(memSidePort.sendAtomic(pkt));
587
588 return lat * clockPeriod();
589 }
590
591 // should assert here that there are no outstanding MSHRs or
592 // writebacks... that would mean that someone used an atomic
593 // access in timing mode
594
595 CacheBlk *blk = nullptr;
596 PacketList writebacks;
597 bool satisfied = access(pkt, blk, lat, writebacks);
598
599 if (pkt->isClean() && blk && blk->isDirty()) {
600 // A cache clean opearation is looking for a dirty
601 // block. If a dirty block is encountered a WriteClean
602 // will update any copies to the path to the memory
603 // until the point of reference.
604 DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
605 __func__, pkt->print(), blk->print());
606 PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(), pkt->id);
607 writebacks.push_back(wb_pkt);
608 pkt->setSatisfied();
609 }
610
611 // handle writebacks resulting from the access here to ensure they
612 // logically precede anything happening below
613 doWritebacksAtomic(writebacks);
614 assert(writebacks.empty());
615
616 if (!satisfied) {
617 lat += handleAtomicReqMiss(pkt, blk, writebacks);
618 }
619
620 // Note that we don't invoke the prefetcher at all in atomic mode.
621 // It's not clear how to do it properly, particularly for
622 // prefetchers that aggressively generate prefetch candidates and
623 // rely on bandwidth contention to throttle them; these will tend
624 // to pollute the cache in atomic mode since there is no bandwidth
625 // contention. If we ever do want to enable prefetching in atomic
626 // mode, though, this is the place to do it... see timingAccess()
627 // for an example (though we'd want to issue the prefetch(es)
628 // immediately rather than calling requestMemSideBus() as we do
629 // there).
630
631 // do any writebacks resulting from the response handling
632 doWritebacksAtomic(writebacks);
633
634 // if we used temp block, check to see if its valid and if so
635 // clear it out, but only do so after the call to recvAtomic is
636 // finished so that any downstream observers (such as a snoop
637 // filter), first see the fill, and only then see the eviction
638 if (blk == tempBlock && tempBlock->isValid()) {
639 // the atomic CPU calls recvAtomic for fetch and load/store
640 // sequentuially, and we may already have a tempBlock
641 // writeback from the fetch that we have not yet sent
642 if (tempBlockWriteback) {
643 // if that is the case, write the prevoius one back, and
644 // do not schedule any new event
645 writebackTempBlockAtomic();
646 } else {
647 // the writeback/clean eviction happens after the call to
648 // recvAtomic has finished (but before any successive
649 // calls), so that the response handling from the fill is
650 // allowed to happen first
651 schedule(writebackTempBlockAtomicEvent, curTick());
652 }
653
654 tempBlockWriteback = evictBlock(blk);
655 }
656
657 if (pkt->needsResponse()) {
658 pkt->makeAtomicResponse();
659 }
660
661 return lat * clockPeriod();
662}
663
664void
665BaseCache::functionalAccess(PacketPtr pkt, bool from_cpu_side)
666{
667 Addr blk_addr = pkt->getBlockAddr(blkSize);
668 bool is_secure = pkt->isSecure();
669 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
670 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
671
672 pkt->pushLabel(name());
673
674 CacheBlkPrintWrapper cbpw(blk);
675
676 // Note that just because an L2/L3 has valid data doesn't mean an
677 // L1 doesn't have a more up-to-date modified copy that still
678 // needs to be found. As a result we always update the request if
679 // we have it, but only declare it satisfied if we are the owner.
680
681 // see if we have data at all (owned or otherwise)
682 bool have_data = blk && blk->isValid()
683 && pkt->trySatisfyFunctional(&cbpw, blk_addr, is_secure, blkSize,
684 blk->data);
685
686 // data we have is dirty if marked as such or if we have an
687 // in-service MSHR that is pending a modified line
688 bool have_dirty =
689 have_data && (blk->isDirty() ||
690 (mshr && mshr->inService && mshr->isPendingModified()));
691
692 bool done = have_dirty ||
693 cpuSidePort.trySatisfyFunctional(pkt) ||
694 mshrQueue.trySatisfyFunctional(pkt, blk_addr) ||
695 writeBuffer.trySatisfyFunctional(pkt, blk_addr) ||
696 memSidePort.trySatisfyFunctional(pkt);
697
698 DPRINTF(CacheVerbose, "%s: %s %s%s%s\n", __func__, pkt->print(),
699 (blk && blk->isValid()) ? "valid " : "",
700 have_data ? "data " : "", done ? "done " : "");
701
702 // We're leaving the cache, so pop cache->name() label
703 pkt->popLabel();
704
705 if (done) {
706 pkt->makeResponse();
707 } else {
708 // if it came as a request from the CPU side then make sure it
709 // continues towards the memory side
710 if (from_cpu_side) {
711 memSidePort.sendFunctional(pkt);
712 } else if (cpuSidePort.isSnooping()) {
713 // if it came from the memory side, it must be a snoop request
714 // and we should only forward it if we are forwarding snoops
715 cpuSidePort.sendFunctionalSnoop(pkt);
716 }
717 }
718}
719
720
721void
722BaseCache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
723{
724 assert(pkt->isRequest());
725
726 uint64_t overwrite_val;
727 bool overwrite_mem;
728 uint64_t condition_val64;
729 uint32_t condition_val32;
730
731 int offset = pkt->getOffset(blkSize);
732 uint8_t *blk_data = blk->data + offset;
733
734 assert(sizeof(uint64_t) >= pkt->getSize());
735
736 overwrite_mem = true;
737 // keep a copy of our possible write value, and copy what is at the
738 // memory address into the packet
739 pkt->writeData((uint8_t *)&overwrite_val);
740 pkt->setData(blk_data);
741
742 if (pkt->req->isCondSwap()) {
743 if (pkt->getSize() == sizeof(uint64_t)) {
744 condition_val64 = pkt->req->getExtraData();
745 overwrite_mem = !std::memcmp(&condition_val64, blk_data,
746 sizeof(uint64_t));
747 } else if (pkt->getSize() == sizeof(uint32_t)) {
748 condition_val32 = (uint32_t)pkt->req->getExtraData();
749 overwrite_mem = !std::memcmp(&condition_val32, blk_data,
750 sizeof(uint32_t));
751 } else
752 panic("Invalid size for conditional read/write\n");
753 }
754
755 if (overwrite_mem) {
756 std::memcpy(blk_data, &overwrite_val, pkt->getSize());
757 blk->status |= BlkDirty;
758 }
759}
760
761QueueEntry*
762BaseCache::getNextQueueEntry()
763{
764 // Check both MSHR queue and write buffer for potential requests,
765 // note that null does not mean there is no request, it could
766 // simply be that it is not ready
767 MSHR *miss_mshr = mshrQueue.getNext();
768 WriteQueueEntry *wq_entry = writeBuffer.getNext();
769
770 // If we got a write buffer request ready, first priority is a
771 // full write buffer, otherwise we favour the miss requests
772 if (wq_entry && (writeBuffer.isFull() || !miss_mshr)) {
773 // need to search MSHR queue for conflicting earlier miss.
774 MSHR *conflict_mshr =
775 mshrQueue.findPending(wq_entry->blkAddr,
776 wq_entry->isSecure);
777
778 if (conflict_mshr && conflict_mshr->order < wq_entry->order) {
779 // Service misses in order until conflict is cleared.
780 return conflict_mshr;
781
782 // @todo Note that we ignore the ready time of the conflict here
783 }
784
785 // No conflicts; issue write
786 return wq_entry;
787 } else if (miss_mshr) {
788 // need to check for conflicting earlier writeback
789 WriteQueueEntry *conflict_mshr =
790 writeBuffer.findPending(miss_mshr->blkAddr,
791 miss_mshr->isSecure);
792 if (conflict_mshr) {
793 // not sure why we don't check order here... it was in the
794 // original code but commented out.
795
796 // The only way this happens is if we are
797 // doing a write and we didn't have permissions
798 // then subsequently saw a writeback (owned got evicted)
799 // We need to make sure to perform the writeback first
800 // To preserve the dirty data, then we can issue the write
801
802 // should we return wq_entry here instead? I.e. do we
803 // have to flush writes in order? I don't think so... not
804 // for Alpha anyway. Maybe for x86?
805 return conflict_mshr;
806
807 // @todo Note that we ignore the ready time of the conflict here
808 }
809
810 // No conflicts; issue read
811 return miss_mshr;
812 }
813
814 // fall through... no pending requests. Try a prefetch.
815 assert(!miss_mshr && !wq_entry);
816 if (prefetcher && mshrQueue.canPrefetch()) {
817 // If we have a miss queue slot, we can try a prefetch
818 PacketPtr pkt = prefetcher->getPacket();
819 if (pkt) {
820 Addr pf_addr = pkt->getBlockAddr(blkSize);
821 if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
822 !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
823 !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
824 // Update statistic on number of prefetches issued
825 // (hwpf_mshr_misses)
826 assert(pkt->req->masterId() < system->maxMasters());
827 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
828
829 // allocate an MSHR and return it, note
830 // that we send the packet straight away, so do not
831 // schedule the send
832 return allocateMissBuffer(pkt, curTick(), false);
833 } else {
834 // free the request and packet
835 delete pkt;
836 }
837 }
838 }
839
840 return nullptr;
841}
842
843void
844BaseCache::satisfyRequest(PacketPtr pkt, CacheBlk *blk, bool, bool)
845{
846 assert(pkt->isRequest());
847
848 assert(blk && blk->isValid());
849 // Occasionally this is not true... if we are a lower-level cache
850 // satisfying a string of Read and ReadEx requests from
851 // upper-level caches, a Read will mark the block as shared but we
852 // can satisfy a following ReadEx anyway since we can rely on the
853 // Read requester(s) to have buffered the ReadEx snoop and to
854 // invalidate their blocks after receiving them.
855 // assert(!pkt->needsWritable() || blk->isWritable());
856 assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
857
858 // Check RMW operations first since both isRead() and
859 // isWrite() will be true for them
860 if (pkt->cmd == MemCmd::SwapReq) {
861 if (pkt->isAtomicOp()) {
862 // extract data from cache and save it into the data field in
863 // the packet as a return value from this atomic op
864
865 int offset = tags->extractBlkOffset(pkt->getAddr());
866 uint8_t *blk_data = blk->data + offset;
867 std::memcpy(pkt->getPtr<uint8_t>(), blk_data, pkt->getSize());
868
869 // execute AMO operation
870 (*(pkt->getAtomicOp()))(blk_data);
871
872 // set block status to dirty
873 blk->status |= BlkDirty;
874 } else {
875 cmpAndSwap(blk, pkt);
876 }
877 } else if (pkt->isWrite()) {
878 // we have the block in a writable state and can go ahead,
879 // note that the line may be also be considered writable in
880 // downstream caches along the path to memory, but always
881 // Exclusive, and never Modified
882 assert(blk->isWritable());
883 // Write or WriteLine at the first cache with block in writable state
884 if (blk->checkWrite(pkt)) {
885 pkt->writeDataToBlock(blk->data, blkSize);
886 }
887 // Always mark the line as dirty (and thus transition to the
888 // Modified state) even if we are a failed StoreCond so we
889 // supply data to any snoops that have appended themselves to
890 // this cache before knowing the store will fail.
891 blk->status |= BlkDirty;
892 DPRINTF(CacheVerbose, "%s for %s (write)\n", __func__, pkt->print());
893 } else if (pkt->isRead()) {
894 if (pkt->isLLSC()) {
895 blk->trackLoadLocked(pkt);
896 }
897
898 // all read responses have a data payload
899 assert(pkt->hasRespData());
900 pkt->setDataFromBlock(blk->data, blkSize);
901 } else if (pkt->isUpgrade()) {
902 // sanity check
903 assert(!pkt->hasSharers());
904
905 if (blk->isDirty()) {
906 // we were in the Owned state, and a cache above us that
907 // has the line in Shared state needs to be made aware
908 // that the data it already has is in fact dirty
909 pkt->setCacheResponding();
910 blk->status &= ~BlkDirty;
911 }
912 } else if (pkt->isClean()) {
913 blk->status &= ~BlkDirty;
914 } else {
915 assert(pkt->isInvalidate());
916 invalidateBlock(blk);
917 DPRINTF(CacheVerbose, "%s for %s (invalidation)\n", __func__,
918 pkt->print());
919 }
920}
921
922/////////////////////////////////////////////////////
923//
924// Access path: requests coming in from the CPU side
925//
926/////////////////////////////////////////////////////
927
928bool
929BaseCache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
930 PacketList &writebacks)
931{
932 // sanity check
933 assert(pkt->isRequest());
934
935 chatty_assert(!(isReadOnly && pkt->isWrite()),
936 "Should never see a write in a read-only cache %s\n",
937 name());
938
939 // Here lat is the value passed as parameter to accessBlock() function
940 // that can modify its value.
941 blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat);
942
943 DPRINTF(Cache, "%s for %s %s\n", __func__, pkt->print(),
944 blk ? "hit " + blk->print() : "miss");
945
946 if (pkt->req->isCacheMaintenance()) {
947 // A cache maintenance operation is always forwarded to the
948 // memory below even if the block is found in dirty state.
949
950 // We defer any changes to the state of the block until we
951 // create and mark as in service the mshr for the downstream
952 // packet.
953 return false;
954 }
955
956 if (pkt->isEviction()) {
957 // We check for presence of block in above caches before issuing
958 // Writeback or CleanEvict to write buffer. Therefore the only
959 // possible cases can be of a CleanEvict packet coming from above
960 // encountering a Writeback generated in this cache peer cache and
961 // waiting in the write buffer. Cases of upper level peer caches
962 // generating CleanEvict and Writeback or simply CleanEvict and
963 // CleanEvict almost simultaneously will be caught by snoops sent out
964 // by crossbar.
965 WriteQueueEntry *wb_entry = writeBuffer.findMatch(pkt->getAddr(),
966 pkt->isSecure());
967 if (wb_entry) {
968 assert(wb_entry->getNumTargets() == 1);
969 PacketPtr wbPkt = wb_entry->getTarget()->pkt;
970 assert(wbPkt->isWriteback());
971
972 if (pkt->isCleanEviction()) {
973 // The CleanEvict and WritebackClean snoops into other
974 // peer caches of the same level while traversing the
975 // crossbar. If a copy of the block is found, the
976 // packet is deleted in the crossbar. Hence, none of
977 // the other upper level caches connected to this
978 // cache have the block, so we can clear the
979 // BLOCK_CACHED flag in the Writeback if set and
980 // discard the CleanEvict by returning true.
981 wbPkt->clearBlockCached();
982 return true;
983 } else {
984 assert(pkt->cmd == MemCmd::WritebackDirty);
985 // Dirty writeback from above trumps our clean
986 // writeback... discard here
987 // Note: markInService will remove entry from writeback buffer.
988 markInService(wb_entry);
989 delete wbPkt;
990 }
991 }
992 }
993
994 // Writeback handling is special case. We can write the block into
995 // the cache without having a writeable copy (or any copy at all).
996 if (pkt->isWriteback()) {
997 assert(blkSize == pkt->getSize());
998
999 // we could get a clean writeback while we are having
1000 // outstanding accesses to a block, do the simple thing for
1001 // now and drop the clean writeback so that we do not upset
1002 // any ordering/decisions about ownership already taken
1003 if (pkt->cmd == MemCmd::WritebackClean &&
1004 mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
1005 DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
1006 "dropping\n", pkt->getAddr());
1007 return true;
1008 }
1009
1010 if (!blk) {
1011 // need to do a replacement
1012 blk = allocateBlock(pkt, writebacks);
1013 if (!blk) {
1014 // no replaceable block available: give up, fwd to next level.
1015 incMissCount(pkt);
1016 return false;
1017 }
1018
1019 blk->status |= (BlkValid | BlkReadable);
1020 }
1021 // only mark the block dirty if we got a writeback command,
1022 // and leave it as is for a clean writeback
1023 if (pkt->cmd == MemCmd::WritebackDirty) {
1024 // TODO: the coherent cache can assert(!blk->isDirty());
1025 blk->status |= BlkDirty;
1026 }
1027 // if the packet does not have sharers, it is passing
1028 // writable, and we got the writeback in Modified or Exclusive
1029 // state, if not we are in the Owned or Shared state
1030 if (!pkt->hasSharers()) {
1031 blk->status |= BlkWritable;
1032 }
1033 // nothing else to do; writeback doesn't expect response
1034 assert(!pkt->needsResponse());
1035 pkt->writeDataToBlock(blk->data, blkSize);
1036 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
1037 incHitCount(pkt);
1038 // populate the time when the block will be ready to access.
1039 blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
1040 pkt->payloadDelay;
1041 return true;
1042 } else if (pkt->cmd == MemCmd::CleanEvict) {
1043 if (blk) {
1044 // Found the block in the tags, need to stop CleanEvict from
1045 // propagating further down the hierarchy. Returning true will
1046 // treat the CleanEvict like a satisfied write request and delete
1047 // it.
1048 return true;
1049 }
1050 // We didn't find the block here, propagate the CleanEvict further
1051 // down the memory hierarchy. Returning false will treat the CleanEvict
1052 // like a Writeback which could not find a replaceable block so has to
1053 // go to next level.
1054 return false;
1055 } else if (pkt->cmd == MemCmd::WriteClean) {
1056 // WriteClean handling is a special case. We can allocate a
1057 // block directly if it doesn't exist and we can update the
1058 // block immediately. The WriteClean transfers the ownership
1059 // of the block as well.
1060 assert(blkSize == pkt->getSize());
1061
1062 if (!blk) {
1063 if (pkt->writeThrough()) {
1064 // if this is a write through packet, we don't try to
1065 // allocate if the block is not present
1066 return false;
1067 } else {
1068 // a writeback that misses needs to allocate a new block
1069 blk = allocateBlock(pkt, writebacks);
1070 if (!blk) {
1071 // no replaceable block available: give up, fwd to
1072 // next level.
1073 incMissCount(pkt);
1074 return false;
1075 }
1076
1077 blk->status |= (BlkValid | BlkReadable);
1078 }
1079 }
1080
1081 // at this point either this is a writeback or a write-through
1082 // write clean operation and the block is already in this
1083 // cache, we need to update the data and the block flags
1084 assert(blk);
1085 // TODO: the coherent cache can assert(!blk->isDirty());
1086 if (!pkt->writeThrough()) {
1087 blk->status |= BlkDirty;
1088 }
1089 // nothing else to do; writeback doesn't expect response
1090 assert(!pkt->needsResponse());
1091 pkt->writeDataToBlock(blk->data, blkSize);
1092 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
1093
1094 incHitCount(pkt);
1095 // populate the time when the block will be ready to access.
1096 blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
1097 pkt->payloadDelay;
1098 // if this a write-through packet it will be sent to cache
1099 // below
1100 return !pkt->writeThrough();
1101 } else if (blk && (pkt->needsWritable() ? blk->isWritable() :
1102 blk->isReadable())) {
1103 // OK to satisfy access
1104 incHitCount(pkt);
1105 satisfyRequest(pkt, blk);
1106 maintainClusivity(pkt->fromCache(), blk);
1107
1108 return true;
1109 }
1110
1111 // Can't satisfy access normally... either no block (blk == nullptr)
1112 // or have block but need writable
1113
1114 incMissCount(pkt);
1115
1116 if (!blk && pkt->isLLSC() && pkt->isWrite()) {
1117 // complete miss on store conditional... just give up now
1118 pkt->req->setExtraData(0);
1119 return true;
1120 }
1121
1122 return false;
1123}
1124
1125void
1126BaseCache::maintainClusivity(bool from_cache, CacheBlk *blk)
1127{
1128 if (from_cache && blk && blk->isValid() && !blk->isDirty() &&
1129 clusivity == Enums::mostly_excl) {
1130 // if we have responded to a cache, and our block is still
1131 // valid, but not dirty, and this cache is mostly exclusive
1132 // with respect to the cache above, drop the block
1133 invalidateBlock(blk);
1134 }
1135}
1136
1137CacheBlk*
1138BaseCache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
1139 bool allocate)
1140{
1141 assert(pkt->isResponse());
1142 Addr addr = pkt->getAddr();
1143 bool is_secure = pkt->isSecure();
1144#if TRACING_ON
1145 CacheBlk::State old_state = blk ? blk->status : 0;
1146#endif
1147
1148 // When handling a fill, we should have no writes to this line.
1149 assert(addr == pkt->getBlockAddr(blkSize));
1150 assert(!writeBuffer.findMatch(addr, is_secure));
1151
1152 if (!blk) {
1153 // better have read new data...
1154 assert(pkt->hasData() || pkt->cmd == MemCmd::InvalidateResp);
1155
1156 // need to do a replacement if allocating, otherwise we stick
1157 // with the temporary storage
1158 blk = allocate ? allocateBlock(pkt, writebacks) : nullptr;
1159
1160 if (!blk) {
1161 // No replaceable block or a mostly exclusive
1162 // cache... just use temporary storage to complete the
1163 // current request and then get rid of it
1164 assert(!tempBlock->isValid());
1165 blk = tempBlock;
1166 tempBlock->insert(addr, is_secure);
1167 DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
1168 is_secure ? "s" : "ns");
1169 }
1170
1171 // we should never be overwriting a valid block
1172 assert(!blk->isValid());
1173 } else {
1174 // existing block... probably an upgrade
1175 assert(regenerateBlkAddr(blk) == addr);
1176 assert(blk->isSecure() == is_secure);
1177 // either we're getting new data or the block should already be valid
1178 assert(pkt->hasData() || blk->isValid());
1179 // don't clear block status... if block is already dirty we
1180 // don't want to lose that
1181 }
1182
1183 blk->status |= BlkValid | BlkReadable;
1184
1185 // sanity check for whole-line writes, which should always be
1186 // marked as writable as part of the fill, and then later marked
1187 // dirty as part of satisfyRequest
1188 if (pkt->cmd == MemCmd::InvalidateResp) {
1189 assert(!pkt->hasSharers());
1190 }
1191
1192 // here we deal with setting the appropriate state of the line,
1193 // and we start by looking at the hasSharers flag, and ignore the
1194 // cacheResponding flag (normally signalling dirty data) if the
1195 // packet has sharers, thus the line is never allocated as Owned
1196 // (dirty but not writable), and always ends up being either
1197 // Shared, Exclusive or Modified, see Packet::setCacheResponding
1198 // for more details
1199 if (!pkt->hasSharers()) {
1200 // we could get a writable line from memory (rather than a
1201 // cache) even in a read-only cache, note that we set this bit
1202 // even for a read-only cache, possibly revisit this decision
1203 blk->status |= BlkWritable;
1204
1205 // check if we got this via cache-to-cache transfer (i.e., from a
1206 // cache that had the block in Modified or Owned state)
1207 if (pkt->cacheResponding()) {
1208 // we got the block in Modified state, and invalidated the
1209 // owners copy
1210 blk->status |= BlkDirty;
1211
1212 chatty_assert(!isReadOnly, "Should never see dirty snoop response "
1213 "in read-only cache %s\n", name());
1214 }
1215 }
1216
1217 DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
1218 addr, is_secure ? "s" : "ns", old_state, blk->print());
1219
1220 // if we got new data, copy it in (checking for a read response
1221 // and a response that has data is the same in the end)
1222 if (pkt->isRead()) {
1223 // sanity checks
1224 assert(pkt->hasData());
1225 assert(pkt->getSize() == blkSize);
1226
1227 pkt->writeDataToBlock(blk->data, blkSize);
1228 }
1229 // We pay for fillLatency here.
1230 blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
1231 pkt->payloadDelay;
1232
1233 return blk;
1234}
1235
1236CacheBlk*
1237BaseCache::allocateBlock(const PacketPtr pkt, PacketList &writebacks)
1238{
1239 // Get address
1240 const Addr addr = pkt->getAddr();
1241
1242 // Get secure bit
1243 const bool is_secure = pkt->isSecure();
1244
1245 // Find replacement victim
1246 std::vector<CacheBlk*> evict_blks;
1247 CacheBlk *victim = tags->findVictim(addr, is_secure, evict_blks);
1248
1249 // It is valid to return nullptr if there is no victim
1250 if (!victim)
1251 return nullptr;
1252
1253 // Print victim block's information
1254 DPRINTF(CacheRepl, "Replacement victim: %s\n", victim->print());
1255
1256 // Check for transient state allocations. If any of the entries listed
1257 // for eviction has a transient state, the allocation fails
1258 for (const auto& blk : evict_blks) {
1259 if (blk->isValid()) {
1260 Addr repl_addr = regenerateBlkAddr(blk);
1261 MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
1262 if (repl_mshr) {
1263 // must be an outstanding upgrade or clean request
1264 // on a block we're about to replace...
1265 assert((!blk->isWritable() && repl_mshr->needsWritable()) ||
1266 repl_mshr->isCleaning());
1267
1268 // too hard to replace block with transient state
1269 // allocation failed, block not inserted
1270 return nullptr;
1271 }
1272 }
1273 }
1274
1275 // The victim will be replaced by a new entry, so increase the replacement
1276 // counter if a valid block is being replaced
1277 if (victim->isValid()) {
1278 DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx "
1279 "(%s): %s\n", regenerateBlkAddr(victim),
1280 victim->isSecure() ? "s" : "ns",
1281 addr, is_secure ? "s" : "ns",
1282 victim->isDirty() ? "writeback" : "clean");
1283
1284 replacements++;
1285 }
1286
1287 // Evict valid blocks associated to this victim block
1288 for (const auto& blk : evict_blks) {
1289 if (blk->isValid()) {
1290 if (blk->wasPrefetched()) {
1291 unusedPrefetches++;
1292 }
1293
1294 evictBlock(blk, writebacks);
1295 }
1296 }
1297
1298 // Insert new block at victimized entry
1299 tags->insertBlock(addr, is_secure, pkt->req->masterId(),
1300 pkt->req->taskId(), victim);
1301
1302 return victim;
1303}
1304
1305void
1306BaseCache::invalidateBlock(CacheBlk *blk)
1307{
1308 if (blk != tempBlock)
1309 tags->invalidate(blk);
1310 blk->invalidate();
1311}
1312
1313void
1314BaseCache::evictBlock(CacheBlk *blk, PacketList &writebacks)
1315{
1316 PacketPtr pkt = evictBlock(blk);
1317 if (pkt) {
1318 writebacks.push_back(pkt);
1319 }
1320}
1321
1322PacketPtr
1323BaseCache::writebackBlk(CacheBlk *blk)
1324{
1325 chatty_assert(!isReadOnly || writebackClean,
1326 "Writeback from read-only cache");
1327 assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
1328
1329 writebacks[Request::wbMasterId]++;
1330
1331 RequestPtr req = std::make_shared<Request>(
1332 regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId);
1333
1334 if (blk->isSecure())
1335 req->setFlags(Request::SECURE);
1336
1337 req->taskId(blk->task_id);
1338
1339 PacketPtr pkt =
1340 new Packet(req, blk->isDirty() ?
1341 MemCmd::WritebackDirty : MemCmd::WritebackClean);
1342
1343 DPRINTF(Cache, "Create Writeback %s writable: %d, dirty: %d\n",
1344 pkt->print(), blk->isWritable(), blk->isDirty());
1345
1346 if (blk->isWritable()) {
1347 // not asserting shared means we pass the block in modified
1348 // state, mark our own block non-writeable
1349 blk->status &= ~BlkWritable;
1350 } else {
1351 // we are in the Owned state, tell the receiver
1352 pkt->setHasSharers();
1353 }
1354
1355 // make sure the block is not marked dirty
1356 blk->status &= ~BlkDirty;
1357
1358 pkt->allocate();
1359 pkt->setDataFromBlock(blk->data, blkSize);
1360
1361 return pkt;
1362}
1363
1364PacketPtr
1365BaseCache::writecleanBlk(CacheBlk *blk, Request::Flags dest, PacketId id)
1366{
1367 RequestPtr req = std::make_shared<Request>(
1368 regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId);
1369
1370 if (blk->isSecure()) {
1371 req->setFlags(Request::SECURE);
1372 }
1373 req->taskId(blk->task_id);
1374
1375 PacketPtr pkt = new Packet(req, MemCmd::WriteClean, blkSize, id);
1376
1377 if (dest) {
1378 req->setFlags(dest);
1379 pkt->setWriteThrough();
1380 }
1381
1382 DPRINTF(Cache, "Create %s writable: %d, dirty: %d\n", pkt->print(),
1383 blk->isWritable(), blk->isDirty());
1384
1385 if (blk->isWritable()) {
1386 // not asserting shared means we pass the block in modified
1387 // state, mark our own block non-writeable
1388 blk->status &= ~BlkWritable;
1389 } else {
1390 // we are in the Owned state, tell the receiver
1391 pkt->setHasSharers();
1392 }
1393
1394 // make sure the block is not marked dirty
1395 blk->status &= ~BlkDirty;
1396
1397 pkt->allocate();
1398 pkt->setDataFromBlock(blk->data, blkSize);
1399
1400 return pkt;
1401}
1402
1403
1404void
1405BaseCache::memWriteback()
1406{
1407 tags->forEachBlk([this](CacheBlk &blk) { writebackVisitor(blk); });
1408}
1409
1410void
1411BaseCache::memInvalidate()
1412{
1413 tags->forEachBlk([this](CacheBlk &blk) { invalidateVisitor(blk); });
1414}
1415
1416bool
1417BaseCache::isDirty() const
1418{
1419 return tags->anyBlk([](CacheBlk &blk) { return blk.isDirty(); });
1420}
1421
1422void
1423BaseCache::writebackVisitor(CacheBlk &blk)
1424{
1425 if (blk.isDirty()) {
1426 assert(blk.isValid());
1427
1428 RequestPtr request = std::make_shared<Request>(
1429 regenerateBlkAddr(&blk), blkSize, 0, Request::funcMasterId);
1430
1431 request->taskId(blk.task_id);
1432 if (blk.isSecure()) {
1433 request->setFlags(Request::SECURE);
1434 }
1435
1436 Packet packet(request, MemCmd::WriteReq);
1437 packet.dataStatic(blk.data);
1438
1439 memSidePort.sendFunctional(&packet);
1440
1441 blk.status &= ~BlkDirty;
1442 }
1443}
1444
1445void
1446BaseCache::invalidateVisitor(CacheBlk &blk)
1447{
1448 if (blk.isDirty())
1449 warn_once("Invalidating dirty cache lines. " \
1450 "Expect things to break.\n");
1451
1452 if (blk.isValid()) {
1453 assert(!blk.isDirty());
1454 invalidateBlock(&blk);
1455 }
1456}
1457
1458Tick
1459BaseCache::nextQueueReadyTime() const
1460{
1461 Tick nextReady = std::min(mshrQueue.nextReadyTime(),
1462 writeBuffer.nextReadyTime());
1463
1464 // Don't signal prefetch ready time if no MSHRs available
1465 // Will signal once enoguh MSHRs are deallocated
1466 if (prefetcher && mshrQueue.canPrefetch()) {
1467 nextReady = std::min(nextReady,
1468 prefetcher->nextPrefetchReadyTime());
1469 }
1470
1471 return nextReady;
1472}
1473
1474
1475bool
1476BaseCache::sendMSHRQueuePacket(MSHR* mshr)
1477{
1478 assert(mshr);
1479
1480 // use request from 1st target
1481 PacketPtr tgt_pkt = mshr->getTarget()->pkt;
1482
1483 DPRINTF(Cache, "%s: MSHR %s\n", __func__, tgt_pkt->print());
1484
1485 // if the cache is in write coalescing mode or (additionally) in
1486 // no allocation mode, and we have a write packet with an MSHR
1487 // that is not a whole-line write (due to incompatible flags etc),
1488 // then reset the write mode
1489 if (writeAllocator && writeAllocator->coalesce() && tgt_pkt->isWrite()) {
1490 if (!mshr->isWholeLineWrite()) {
1491 // if we are currently write coalescing, hold on the
1492 // MSHR as many cycles extra as we need to completely
1493 // write a cache line
1494 if (writeAllocator->delay(mshr->blkAddr)) {
1495 Tick delay = blkSize / tgt_pkt->getSize() * clockPeriod();
1496 DPRINTF(CacheVerbose, "Delaying pkt %s %llu ticks to allow "
1497 "for write coalescing\n", tgt_pkt->print(), delay);
1498 mshrQueue.delay(mshr, delay);
1499 return false;
1500 } else {
1501 writeAllocator->reset();
1502 }
1503 } else {
1504 writeAllocator->resetDelay(mshr->blkAddr);
1505 }
1506 }
1507
1508 CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
1509
1510 // either a prefetch that is not present upstream, or a normal
1511 // MSHR request, proceed to get the packet to send downstream
1512 PacketPtr pkt = createMissPacket(tgt_pkt, blk, mshr->needsWritable(),
1513 mshr->isWholeLineWrite());
1514
1515 mshr->isForward = (pkt == nullptr);
1516
1517 if (mshr->isForward) {
1518 // not a cache block request, but a response is expected
1519 // make copy of current packet to forward, keep current
1520 // copy for response handling
1521 pkt = new Packet(tgt_pkt, false, true);
1522 assert(!pkt->isWrite());
1523 }
1524
1525 // play it safe and append (rather than set) the sender state,
1526 // as forwarded packets may already have existing state
1527 pkt->pushSenderState(mshr);
1528
1529 if (pkt->isClean() && blk && blk->isDirty()) {
1530 // A cache clean opearation is looking for a dirty block. Mark
1531 // the packet so that the destination xbar can determine that
1532 // there will be a follow-up write packet as well.
1533 pkt->setSatisfied();
1534 }
1535
1536 if (!memSidePort.sendTimingReq(pkt)) {
1537 // we are awaiting a retry, but we
1538 // delete the packet and will be creating a new packet
1539 // when we get the opportunity
1540 delete pkt;
1541
1542 // note that we have now masked any requestBus and
1543 // schedSendEvent (we will wait for a retry before
1544 // doing anything), and this is so even if we do not
1545 // care about this packet and might override it before
1546 // it gets retried
1547 return true;
1548 } else {
1549 // As part of the call to sendTimingReq the packet is
1550 // forwarded to all neighbouring caches (and any caches
1551 // above them) as a snoop. Thus at this point we know if
1552 // any of the neighbouring caches are responding, and if
1553 // so, we know it is dirty, and we can determine if it is
1554 // being passed as Modified, making our MSHR the ordering
1555 // point
1556 bool pending_modified_resp = !pkt->hasSharers() &&
1557 pkt->cacheResponding();
1558 markInService(mshr, pending_modified_resp);
1559
1560 if (pkt->isClean() && blk && blk->isDirty()) {
1561 // A cache clean opearation is looking for a dirty
1562 // block. If a dirty block is encountered a WriteClean
1563 // will update any copies to the path to the memory
1564 // until the point of reference.
1565 DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
1566 __func__, pkt->print(), blk->print());
1567 PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(),
1568 pkt->id);
1569 PacketList writebacks;
1570 writebacks.push_back(wb_pkt);
1571 doWritebacks(writebacks, 0);
1572 }
1573
1574 return false;
1575 }
1576}
1577
1578bool
1579BaseCache::sendWriteQueuePacket(WriteQueueEntry* wq_entry)
1580{
1581 assert(wq_entry);
1582
1583 // always a single target for write queue entries
1584 PacketPtr tgt_pkt = wq_entry->getTarget()->pkt;
1585
1586 DPRINTF(Cache, "%s: write %s\n", __func__, tgt_pkt->print());
1587
1588 // forward as is, both for evictions and uncacheable writes
1589 if (!memSidePort.sendTimingReq(tgt_pkt)) {
1590 // note that we have now masked any requestBus and
1591 // schedSendEvent (we will wait for a retry before
1592 // doing anything), and this is so even if we do not
1593 // care about this packet and might override it before
1594 // it gets retried
1595 return true;
1596 } else {
1597 markInService(wq_entry);
1598 return false;
1599 }
1600}
1601
1602void
1603BaseCache::serialize(CheckpointOut &cp) const
1604{
1605 bool dirty(isDirty());
1606
1607 if (dirty) {
1608 warn("*** The cache still contains dirty data. ***\n");
1609 warn(" Make sure to drain the system using the correct flags.\n");
1610 warn(" This checkpoint will not restore correctly " \
1611 "and dirty data in the cache will be lost!\n");
1612 }
1613
1614 // Since we don't checkpoint the data in the cache, any dirty data
1615 // will be lost when restoring from a checkpoint of a system that
1616 // wasn't drained properly. Flag the checkpoint as invalid if the
1617 // cache contains dirty data.
1618 bool bad_checkpoint(dirty);
1619 SERIALIZE_SCALAR(bad_checkpoint);
1620}
1621
1622void
1623BaseCache::unserialize(CheckpointIn &cp)
1624{
1625 bool bad_checkpoint;
1626 UNSERIALIZE_SCALAR(bad_checkpoint);
1627 if (bad_checkpoint) {
1628 fatal("Restoring from checkpoints with dirty caches is not "
1629 "supported in the classic memory system. Please remove any "
1630 "caches or drain them properly before taking checkpoints.\n");
1631 }
1632}
1633
1634void
1635BaseCache::regStats()
1636{
1637 MemObject::regStats();
1638
1639 using namespace Stats;
1640
1641 // Hit statistics
1642 for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1643 MemCmd cmd(access_idx);
1644 const string &cstr = cmd.toString();
1645
1646 hits[access_idx]
1647 .init(system->maxMasters())
1648 .name(name() + "." + cstr + "_hits")
1649 .desc("number of " + cstr + " hits")
1650 .flags(total | nozero | nonan)
1651 ;
1652 for (int i = 0; i < system->maxMasters(); i++) {
1653 hits[access_idx].subname(i, system->getMasterName(i));
1654 }
1655 }
1656
1657// These macros make it easier to sum the right subset of commands and
1658// to change the subset of commands that are considered "demand" vs
1659// "non-demand"
1660#define SUM_DEMAND(s) \
1661 (s[MemCmd::ReadReq] + s[MemCmd::WriteReq] + s[MemCmd::WriteLineReq] + \
1662 s[MemCmd::ReadExReq] + s[MemCmd::ReadCleanReq] + s[MemCmd::ReadSharedReq])
1663
1664// should writebacks be included here? prior code was inconsistent...
1665#define SUM_NON_DEMAND(s) \
| 1/*
2 * Copyright (c) 2012-2013, 2018 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2003-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Erik Hallnor
41 * Nikos Nikoleris
42 */
43
44/**
45 * @file
46 * Definition of BaseCache functions.
47 */
48
49#include "mem/cache/base.hh"
50
51#include "base/compiler.hh"
52#include "base/logging.hh"
53#include "debug/Cache.hh"
54#include "debug/CachePort.hh"
55#include "debug/CacheRepl.hh"
56#include "debug/CacheVerbose.hh"
57#include "mem/cache/mshr.hh"
58#include "mem/cache/prefetch/base.hh"
59#include "mem/cache/queue_entry.hh"
60#include "params/BaseCache.hh"
61#include "params/WriteAllocator.hh"
62#include "sim/core.hh"
63
64class BaseMasterPort;
65class BaseSlavePort;
66
67using namespace std;
68
69BaseCache::CacheSlavePort::CacheSlavePort(const std::string &_name,
70 BaseCache *_cache,
71 const std::string &_label)
72 : QueuedSlavePort(_name, _cache, queue), queue(*_cache, *this, _label),
73 blocked(false), mustSendRetry(false),
74 sendRetryEvent([this]{ processSendRetry(); }, _name)
75{
76}
77
78BaseCache::BaseCache(const BaseCacheParams *p, unsigned blk_size)
79 : MemObject(p),
80 cpuSidePort (p->name + ".cpu_side", this, "CpuSidePort"),
81 memSidePort(p->name + ".mem_side", this, "MemSidePort"),
82 mshrQueue("MSHRs", p->mshrs, 0, p->demand_mshr_reserve), // see below
83 writeBuffer("write buffer", p->write_buffers, p->mshrs), // see below
84 tags(p->tags),
85 prefetcher(p->prefetcher),
86 prefetchOnAccess(p->prefetch_on_access),
87 writeAllocator(p->write_allocator),
88 writebackClean(p->writeback_clean),
89 tempBlockWriteback(nullptr),
90 writebackTempBlockAtomicEvent([this]{ writebackTempBlockAtomic(); },
91 name(), false,
92 EventBase::Delayed_Writeback_Pri),
93 blkSize(blk_size),
94 lookupLatency(p->tag_latency),
95 dataLatency(p->data_latency),
96 forwardLatency(p->tag_latency),
97 fillLatency(p->data_latency),
98 responseLatency(p->response_latency),
99 numTarget(p->tgts_per_mshr),
100 forwardSnoops(true),
101 clusivity(p->clusivity),
102 isReadOnly(p->is_read_only),
103 blocked(0),
104 order(0),
105 noTargetMSHR(nullptr),
106 missCount(p->max_miss_count),
107 addrRanges(p->addr_ranges.begin(), p->addr_ranges.end()),
108 system(p->system)
109{
110 // the MSHR queue has no reserve entries as we check the MSHR
111 // queue on every single allocation, whereas the write queue has
112 // as many reserve entries as we have MSHRs, since every MSHR may
113 // eventually require a writeback, and we do not check the write
114 // buffer before committing to an MSHR
115
116 // forward snoops is overridden in init() once we can query
117 // whether the connected master is actually snooping or not
118
119 tempBlock = new TempCacheBlk(blkSize);
120
121 tags->init(this);
122 if (prefetcher)
123 prefetcher->setCache(this);
124}
125
126BaseCache::~BaseCache()
127{
128 delete tempBlock;
129}
130
131void
132BaseCache::CacheSlavePort::setBlocked()
133{
134 assert(!blocked);
135 DPRINTF(CachePort, "Port is blocking new requests\n");
136 blocked = true;
137 // if we already scheduled a retry in this cycle, but it has not yet
138 // happened, cancel it
139 if (sendRetryEvent.scheduled()) {
140 owner.deschedule(sendRetryEvent);
141 DPRINTF(CachePort, "Port descheduled retry\n");
142 mustSendRetry = true;
143 }
144}
145
146void
147BaseCache::CacheSlavePort::clearBlocked()
148{
149 assert(blocked);
150 DPRINTF(CachePort, "Port is accepting new requests\n");
151 blocked = false;
152 if (mustSendRetry) {
153 // @TODO: need to find a better time (next cycle?)
154 owner.schedule(sendRetryEvent, curTick() + 1);
155 }
156}
157
158void
159BaseCache::CacheSlavePort::processSendRetry()
160{
161 DPRINTF(CachePort, "Port is sending retry\n");
162
163 // reset the flag and call retry
164 mustSendRetry = false;
165 sendRetryReq();
166}
167
168Addr
169BaseCache::regenerateBlkAddr(CacheBlk* blk)
170{
171 if (blk != tempBlock) {
172 return tags->regenerateBlkAddr(blk);
173 } else {
174 return tempBlock->getAddr();
175 }
176}
177
178void
179BaseCache::init()
180{
181 if (!cpuSidePort.isConnected() || !memSidePort.isConnected())
182 fatal("Cache ports on %s are not connected\n", name());
183 cpuSidePort.sendRangeChange();
184 forwardSnoops = cpuSidePort.isSnooping();
185}
186
187BaseMasterPort &
188BaseCache::getMasterPort(const std::string &if_name, PortID idx)
189{
190 if (if_name == "mem_side") {
191 return memSidePort;
192 } else {
193 return MemObject::getMasterPort(if_name, idx);
194 }
195}
196
197BaseSlavePort &
198BaseCache::getSlavePort(const std::string &if_name, PortID idx)
199{
200 if (if_name == "cpu_side") {
201 return cpuSidePort;
202 } else {
203 return MemObject::getSlavePort(if_name, idx);
204 }
205}
206
207bool
208BaseCache::inRange(Addr addr) const
209{
210 for (const auto& r : addrRanges) {
211 if (r.contains(addr)) {
212 return true;
213 }
214 }
215 return false;
216}
217
218void
219BaseCache::handleTimingReqHit(PacketPtr pkt, CacheBlk *blk, Tick request_time)
220{
221 if (pkt->needsResponse()) {
222 pkt->makeTimingResponse();
223 // @todo: Make someone pay for this
224 pkt->headerDelay = pkt->payloadDelay = 0;
225
226 // In this case we are considering request_time that takes
227 // into account the delay of the xbar, if any, and just
228 // lat, neglecting responseLatency, modelling hit latency
229 // just as lookupLatency or or the value of lat overriden
230 // by access(), that calls accessBlock() function.
231 cpuSidePort.schedTimingResp(pkt, request_time, true);
232 } else {
233 DPRINTF(Cache, "%s satisfied %s, no response needed\n", __func__,
234 pkt->print());
235
236 // queue the packet for deletion, as the sending cache is
237 // still relying on it; if the block is found in access(),
238 // CleanEvict and Writeback messages will be deleted
239 // here as well
240 pendingDelete.reset(pkt);
241 }
242}
243
244void
245BaseCache::handleTimingReqMiss(PacketPtr pkt, MSHR *mshr, CacheBlk *blk,
246 Tick forward_time, Tick request_time)
247{
248 if (writeAllocator &&
249 pkt && pkt->isWrite() && !pkt->req->isUncacheable()) {
250 writeAllocator->updateMode(pkt->getAddr(), pkt->getSize(),
251 pkt->getBlockAddr(blkSize));
252 }
253
254 if (mshr) {
255 /// MSHR hit
256 /// @note writebacks will be checked in getNextMSHR()
257 /// for any conflicting requests to the same block
258
259 //@todo remove hw_pf here
260
261 // Coalesce unless it was a software prefetch (see above).
262 if (pkt) {
263 assert(!pkt->isWriteback());
264 // CleanEvicts corresponding to blocks which have
265 // outstanding requests in MSHRs are simply sunk here
266 if (pkt->cmd == MemCmd::CleanEvict) {
267 pendingDelete.reset(pkt);
268 } else if (pkt->cmd == MemCmd::WriteClean) {
269 // A WriteClean should never coalesce with any
270 // outstanding cache maintenance requests.
271
272 // We use forward_time here because there is an
273 // uncached memory write, forwarded to WriteBuffer.
274 allocateWriteBuffer(pkt, forward_time);
275 } else {
276 DPRINTF(Cache, "%s coalescing MSHR for %s\n", __func__,
277 pkt->print());
278
279 assert(pkt->req->masterId() < system->maxMasters());
280 mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
281
282 // We use forward_time here because it is the same
283 // considering new targets. We have multiple
284 // requests for the same address here. It
285 // specifies the latency to allocate an internal
286 // buffer and to schedule an event to the queued
287 // port and also takes into account the additional
288 // delay of the xbar.
289 mshr->allocateTarget(pkt, forward_time, order++,
290 allocOnFill(pkt->cmd));
291 if (mshr->getNumTargets() == numTarget) {
292 noTargetMSHR = mshr;
293 setBlocked(Blocked_NoTargets);
294 // need to be careful with this... if this mshr isn't
295 // ready yet (i.e. time > curTick()), we don't want to
296 // move it ahead of mshrs that are ready
297 // mshrQueue.moveToFront(mshr);
298 }
299 }
300 }
301 } else {
302 // no MSHR
303 assert(pkt->req->masterId() < system->maxMasters());
304 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
305
306 if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean) {
307 // We use forward_time here because there is an
308 // writeback or writeclean, forwarded to WriteBuffer.
309 allocateWriteBuffer(pkt, forward_time);
310 } else {
311 if (blk && blk->isValid()) {
312 // If we have a write miss to a valid block, we
313 // need to mark the block non-readable. Otherwise
314 // if we allow reads while there's an outstanding
315 // write miss, the read could return stale data
316 // out of the cache block... a more aggressive
317 // system could detect the overlap (if any) and
318 // forward data out of the MSHRs, but we don't do
319 // that yet. Note that we do need to leave the
320 // block valid so that it stays in the cache, in
321 // case we get an upgrade response (and hence no
322 // new data) when the write miss completes.
323 // As long as CPUs do proper store/load forwarding
324 // internally, and have a sufficiently weak memory
325 // model, this is probably unnecessary, but at some
326 // point it must have seemed like we needed it...
327 assert((pkt->needsWritable() && !blk->isWritable()) ||
328 pkt->req->isCacheMaintenance());
329 blk->status &= ~BlkReadable;
330 }
331 // Here we are using forward_time, modelling the latency of
332 // a miss (outbound) just as forwardLatency, neglecting the
333 // lookupLatency component.
334 allocateMissBuffer(pkt, forward_time);
335 }
336 }
337}
338
339void
340BaseCache::recvTimingReq(PacketPtr pkt)
341{
342 // anything that is merely forwarded pays for the forward latency and
343 // the delay provided by the crossbar
344 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
345
346 // We use lookupLatency here because it is used to specify the latency
347 // to access.
348 Cycles lat = lookupLatency;
349 CacheBlk *blk = nullptr;
350 bool satisfied = false;
351 {
352 PacketList writebacks;
353 // Note that lat is passed by reference here. The function
354 // access() calls accessBlock() which can modify lat value.
355 satisfied = access(pkt, blk, lat, writebacks);
356
357 // copy writebacks to write buffer here to ensure they logically
358 // precede anything happening below
359 doWritebacks(writebacks, forward_time);
360 }
361
362 // Here we charge the headerDelay that takes into account the latencies
363 // of the bus, if the packet comes from it.
364 // The latency charged it is just lat that is the value of lookupLatency
365 // modified by access() function, or if not just lookupLatency.
366 // In case of a hit we are neglecting response latency.
367 // In case of a miss we are neglecting forward latency.
368 Tick request_time = clockEdge(lat) + pkt->headerDelay;
369 // Here we reset the timing of the packet.
370 pkt->headerDelay = pkt->payloadDelay = 0;
371 // track time of availability of next prefetch, if any
372 Tick next_pf_time = MaxTick;
373
374 if (satisfied) {
375 // if need to notify the prefetcher we have to do it before
376 // anything else as later handleTimingReqHit might turn the
377 // packet in a response
378 if (prefetcher &&
379 (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
380 if (blk)
381 blk->status &= ~BlkHWPrefetched;
382
383 // Don't notify on SWPrefetch
384 if (!pkt->cmd.isSWPrefetch()) {
385 assert(!pkt->req->isCacheMaintenance());
386 next_pf_time = prefetcher->notify(pkt);
387 }
388 }
389
390 handleTimingReqHit(pkt, blk, request_time);
391 } else {
392 handleTimingReqMiss(pkt, blk, forward_time, request_time);
393
394 // We should call the prefetcher reguardless if the request is
395 // satisfied or not, reguardless if the request is in the MSHR
396 // or not. The request could be a ReadReq hit, but still not
397 // satisfied (potentially because of a prior write to the same
398 // cache line. So, even when not satisfied, there is an MSHR
399 // already allocated for this, we need to let the prefetcher
400 // know about the request
401
402 // Don't notify prefetcher on SWPrefetch, cache maintenance
403 // operations or for writes that we are coaslescing.
404 if (prefetcher && pkt &&
405 !pkt->cmd.isSWPrefetch() &&
406 !pkt->req->isCacheMaintenance() &&
407 !(writeAllocator && writeAllocator->coalesce() &&
408 pkt->isWrite())) {
409 next_pf_time = prefetcher->notify(pkt);
410 }
411 }
412
413 if (next_pf_time != MaxTick) {
414 schedMemSideSendEvent(next_pf_time);
415 }
416}
417
418void
419BaseCache::handleUncacheableWriteResp(PacketPtr pkt)
420{
421 Tick completion_time = clockEdge(responseLatency) +
422 pkt->headerDelay + pkt->payloadDelay;
423
424 // Reset the bus additional time as it is now accounted for
425 pkt->headerDelay = pkt->payloadDelay = 0;
426
427 cpuSidePort.schedTimingResp(pkt, completion_time, true);
428}
429
430void
431BaseCache::recvTimingResp(PacketPtr pkt)
432{
433 assert(pkt->isResponse());
434
435 // all header delay should be paid for by the crossbar, unless
436 // this is a prefetch response from above
437 panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
438 "%s saw a non-zero packet delay\n", name());
439
440 const bool is_error = pkt->isError();
441
442 if (is_error) {
443 DPRINTF(Cache, "%s: Cache received %s with error\n", __func__,
444 pkt->print());
445 }
446
447 DPRINTF(Cache, "%s: Handling response %s\n", __func__,
448 pkt->print());
449
450 // if this is a write, we should be looking at an uncacheable
451 // write
452 if (pkt->isWrite()) {
453 assert(pkt->req->isUncacheable());
454 handleUncacheableWriteResp(pkt);
455 return;
456 }
457
458 // we have dealt with any (uncacheable) writes above, from here on
459 // we know we are dealing with an MSHR due to a miss or a prefetch
460 MSHR *mshr = dynamic_cast<MSHR*>(pkt->popSenderState());
461 assert(mshr);
462
463 if (mshr == noTargetMSHR) {
464 // we always clear at least one target
465 clearBlocked(Blocked_NoTargets);
466 noTargetMSHR = nullptr;
467 }
468
469 // Initial target is used just for stats
470 MSHR::Target *initial_tgt = mshr->getTarget();
471 int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
472 Tick miss_latency = curTick() - initial_tgt->recvTime;
473
474 if (pkt->req->isUncacheable()) {
475 assert(pkt->req->masterId() < system->maxMasters());
476 mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
477 miss_latency;
478 } else {
479 assert(pkt->req->masterId() < system->maxMasters());
480 mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
481 miss_latency;
482 }
483
484 PacketList writebacks;
485
486 bool is_fill = !mshr->isForward &&
487 (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp ||
488 mshr->wasWholeLineWrite);
489
490 // make sure that if the mshr was due to a whole line write then
491 // the response is an invalidation
492 assert(!mshr->wasWholeLineWrite || pkt->isInvalidate());
493
494 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
495
496 if (is_fill && !is_error) {
497 DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
498 pkt->getAddr());
499
500 const bool allocate = (writeAllocator && mshr->wasWholeLineWrite) ?
501 writeAllocator->allocate() : mshr->allocOnFill();
502 blk = handleFill(pkt, blk, writebacks, allocate);
503 assert(blk != nullptr);
504 }
505
506 if (blk && blk->isValid() && pkt->isClean() && !pkt->isInvalidate()) {
507 // The block was marked not readable while there was a pending
508 // cache maintenance operation, restore its flag.
509 blk->status |= BlkReadable;
510
511 // This was a cache clean operation (without invalidate)
512 // and we have a copy of the block already. Since there
513 // is no invalidation, we can promote targets that don't
514 // require a writable copy
515 mshr->promoteReadable();
516 }
517
518 if (blk && blk->isWritable() && !pkt->req->isCacheInvalidate()) {
519 // If at this point the referenced block is writable and the
520 // response is not a cache invalidate, we promote targets that
521 // were deferred as we couldn't guarrantee a writable copy
522 mshr->promoteWritable();
523 }
524
525 serviceMSHRTargets(mshr, pkt, blk, writebacks);
526
527 if (mshr->promoteDeferredTargets()) {
528 // avoid later read getting stale data while write miss is
529 // outstanding.. see comment in timingAccess()
530 if (blk) {
531 blk->status &= ~BlkReadable;
532 }
533 mshrQueue.markPending(mshr);
534 schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
535 } else {
536 // while we deallocate an mshr from the queue we still have to
537 // check the isFull condition before and after as we might
538 // have been using the reserved entries already
539 const bool was_full = mshrQueue.isFull();
540 mshrQueue.deallocate(mshr);
541 if (was_full && !mshrQueue.isFull()) {
542 clearBlocked(Blocked_NoMSHRs);
543 }
544
545 // Request the bus for a prefetch if this deallocation freed enough
546 // MSHRs for a prefetch to take place
547 if (prefetcher && mshrQueue.canPrefetch()) {
548 Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
549 clockEdge());
550 if (next_pf_time != MaxTick)
551 schedMemSideSendEvent(next_pf_time);
552 }
553 }
554
555 // if we used temp block, check to see if its valid and then clear it out
556 if (blk == tempBlock && tempBlock->isValid()) {
557 evictBlock(blk, writebacks);
558 }
559
560 const Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
561 // copy writebacks to write buffer
562 doWritebacks(writebacks, forward_time);
563
564 DPRINTF(CacheVerbose, "%s: Leaving with %s\n", __func__, pkt->print());
565 delete pkt;
566}
567
568
569Tick
570BaseCache::recvAtomic(PacketPtr pkt)
571{
572 // We are in atomic mode so we pay just for lookupLatency here.
573 Cycles lat = lookupLatency;
574
575 // follow the same flow as in recvTimingReq, and check if a cache
576 // above us is responding
577 if (pkt->cacheResponding() && !pkt->isClean()) {
578 assert(!pkt->req->isCacheInvalidate());
579 DPRINTF(Cache, "Cache above responding to %s: not responding\n",
580 pkt->print());
581
582 // if a cache is responding, and it had the line in Owned
583 // rather than Modified state, we need to invalidate any
584 // copies that are not on the same path to memory
585 assert(pkt->needsWritable() && !pkt->responderHadWritable());
586 lat += ticksToCycles(memSidePort.sendAtomic(pkt));
587
588 return lat * clockPeriod();
589 }
590
591 // should assert here that there are no outstanding MSHRs or
592 // writebacks... that would mean that someone used an atomic
593 // access in timing mode
594
595 CacheBlk *blk = nullptr;
596 PacketList writebacks;
597 bool satisfied = access(pkt, blk, lat, writebacks);
598
599 if (pkt->isClean() && blk && blk->isDirty()) {
600 // A cache clean opearation is looking for a dirty
601 // block. If a dirty block is encountered a WriteClean
602 // will update any copies to the path to the memory
603 // until the point of reference.
604 DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
605 __func__, pkt->print(), blk->print());
606 PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(), pkt->id);
607 writebacks.push_back(wb_pkt);
608 pkt->setSatisfied();
609 }
610
611 // handle writebacks resulting from the access here to ensure they
612 // logically precede anything happening below
613 doWritebacksAtomic(writebacks);
614 assert(writebacks.empty());
615
616 if (!satisfied) {
617 lat += handleAtomicReqMiss(pkt, blk, writebacks);
618 }
619
620 // Note that we don't invoke the prefetcher at all in atomic mode.
621 // It's not clear how to do it properly, particularly for
622 // prefetchers that aggressively generate prefetch candidates and
623 // rely on bandwidth contention to throttle them; these will tend
624 // to pollute the cache in atomic mode since there is no bandwidth
625 // contention. If we ever do want to enable prefetching in atomic
626 // mode, though, this is the place to do it... see timingAccess()
627 // for an example (though we'd want to issue the prefetch(es)
628 // immediately rather than calling requestMemSideBus() as we do
629 // there).
630
631 // do any writebacks resulting from the response handling
632 doWritebacksAtomic(writebacks);
633
634 // if we used temp block, check to see if its valid and if so
635 // clear it out, but only do so after the call to recvAtomic is
636 // finished so that any downstream observers (such as a snoop
637 // filter), first see the fill, and only then see the eviction
638 if (blk == tempBlock && tempBlock->isValid()) {
639 // the atomic CPU calls recvAtomic for fetch and load/store
640 // sequentuially, and we may already have a tempBlock
641 // writeback from the fetch that we have not yet sent
642 if (tempBlockWriteback) {
643 // if that is the case, write the prevoius one back, and
644 // do not schedule any new event
645 writebackTempBlockAtomic();
646 } else {
647 // the writeback/clean eviction happens after the call to
648 // recvAtomic has finished (but before any successive
649 // calls), so that the response handling from the fill is
650 // allowed to happen first
651 schedule(writebackTempBlockAtomicEvent, curTick());
652 }
653
654 tempBlockWriteback = evictBlock(blk);
655 }
656
657 if (pkt->needsResponse()) {
658 pkt->makeAtomicResponse();
659 }
660
661 return lat * clockPeriod();
662}
663
664void
665BaseCache::functionalAccess(PacketPtr pkt, bool from_cpu_side)
666{
667 Addr blk_addr = pkt->getBlockAddr(blkSize);
668 bool is_secure = pkt->isSecure();
669 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
670 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
671
672 pkt->pushLabel(name());
673
674 CacheBlkPrintWrapper cbpw(blk);
675
676 // Note that just because an L2/L3 has valid data doesn't mean an
677 // L1 doesn't have a more up-to-date modified copy that still
678 // needs to be found. As a result we always update the request if
679 // we have it, but only declare it satisfied if we are the owner.
680
681 // see if we have data at all (owned or otherwise)
682 bool have_data = blk && blk->isValid()
683 && pkt->trySatisfyFunctional(&cbpw, blk_addr, is_secure, blkSize,
684 blk->data);
685
686 // data we have is dirty if marked as such or if we have an
687 // in-service MSHR that is pending a modified line
688 bool have_dirty =
689 have_data && (blk->isDirty() ||
690 (mshr && mshr->inService && mshr->isPendingModified()));
691
692 bool done = have_dirty ||
693 cpuSidePort.trySatisfyFunctional(pkt) ||
694 mshrQueue.trySatisfyFunctional(pkt, blk_addr) ||
695 writeBuffer.trySatisfyFunctional(pkt, blk_addr) ||
696 memSidePort.trySatisfyFunctional(pkt);
697
698 DPRINTF(CacheVerbose, "%s: %s %s%s%s\n", __func__, pkt->print(),
699 (blk && blk->isValid()) ? "valid " : "",
700 have_data ? "data " : "", done ? "done " : "");
701
702 // We're leaving the cache, so pop cache->name() label
703 pkt->popLabel();
704
705 if (done) {
706 pkt->makeResponse();
707 } else {
708 // if it came as a request from the CPU side then make sure it
709 // continues towards the memory side
710 if (from_cpu_side) {
711 memSidePort.sendFunctional(pkt);
712 } else if (cpuSidePort.isSnooping()) {
713 // if it came from the memory side, it must be a snoop request
714 // and we should only forward it if we are forwarding snoops
715 cpuSidePort.sendFunctionalSnoop(pkt);
716 }
717 }
718}
719
720
721void
722BaseCache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
723{
724 assert(pkt->isRequest());
725
726 uint64_t overwrite_val;
727 bool overwrite_mem;
728 uint64_t condition_val64;
729 uint32_t condition_val32;
730
731 int offset = pkt->getOffset(blkSize);
732 uint8_t *blk_data = blk->data + offset;
733
734 assert(sizeof(uint64_t) >= pkt->getSize());
735
736 overwrite_mem = true;
737 // keep a copy of our possible write value, and copy what is at the
738 // memory address into the packet
739 pkt->writeData((uint8_t *)&overwrite_val);
740 pkt->setData(blk_data);
741
742 if (pkt->req->isCondSwap()) {
743 if (pkt->getSize() == sizeof(uint64_t)) {
744 condition_val64 = pkt->req->getExtraData();
745 overwrite_mem = !std::memcmp(&condition_val64, blk_data,
746 sizeof(uint64_t));
747 } else if (pkt->getSize() == sizeof(uint32_t)) {
748 condition_val32 = (uint32_t)pkt->req->getExtraData();
749 overwrite_mem = !std::memcmp(&condition_val32, blk_data,
750 sizeof(uint32_t));
751 } else
752 panic("Invalid size for conditional read/write\n");
753 }
754
755 if (overwrite_mem) {
756 std::memcpy(blk_data, &overwrite_val, pkt->getSize());
757 blk->status |= BlkDirty;
758 }
759}
760
761QueueEntry*
762BaseCache::getNextQueueEntry()
763{
764 // Check both MSHR queue and write buffer for potential requests,
765 // note that null does not mean there is no request, it could
766 // simply be that it is not ready
767 MSHR *miss_mshr = mshrQueue.getNext();
768 WriteQueueEntry *wq_entry = writeBuffer.getNext();
769
770 // If we got a write buffer request ready, first priority is a
771 // full write buffer, otherwise we favour the miss requests
772 if (wq_entry && (writeBuffer.isFull() || !miss_mshr)) {
773 // need to search MSHR queue for conflicting earlier miss.
774 MSHR *conflict_mshr =
775 mshrQueue.findPending(wq_entry->blkAddr,
776 wq_entry->isSecure);
777
778 if (conflict_mshr && conflict_mshr->order < wq_entry->order) {
779 // Service misses in order until conflict is cleared.
780 return conflict_mshr;
781
782 // @todo Note that we ignore the ready time of the conflict here
783 }
784
785 // No conflicts; issue write
786 return wq_entry;
787 } else if (miss_mshr) {
788 // need to check for conflicting earlier writeback
789 WriteQueueEntry *conflict_mshr =
790 writeBuffer.findPending(miss_mshr->blkAddr,
791 miss_mshr->isSecure);
792 if (conflict_mshr) {
793 // not sure why we don't check order here... it was in the
794 // original code but commented out.
795
796 // The only way this happens is if we are
797 // doing a write and we didn't have permissions
798 // then subsequently saw a writeback (owned got evicted)
799 // We need to make sure to perform the writeback first
800 // To preserve the dirty data, then we can issue the write
801
802 // should we return wq_entry here instead? I.e. do we
803 // have to flush writes in order? I don't think so... not
804 // for Alpha anyway. Maybe for x86?
805 return conflict_mshr;
806
807 // @todo Note that we ignore the ready time of the conflict here
808 }
809
810 // No conflicts; issue read
811 return miss_mshr;
812 }
813
814 // fall through... no pending requests. Try a prefetch.
815 assert(!miss_mshr && !wq_entry);
816 if (prefetcher && mshrQueue.canPrefetch()) {
817 // If we have a miss queue slot, we can try a prefetch
818 PacketPtr pkt = prefetcher->getPacket();
819 if (pkt) {
820 Addr pf_addr = pkt->getBlockAddr(blkSize);
821 if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
822 !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
823 !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
824 // Update statistic on number of prefetches issued
825 // (hwpf_mshr_misses)
826 assert(pkt->req->masterId() < system->maxMasters());
827 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
828
829 // allocate an MSHR and return it, note
830 // that we send the packet straight away, so do not
831 // schedule the send
832 return allocateMissBuffer(pkt, curTick(), false);
833 } else {
834 // free the request and packet
835 delete pkt;
836 }
837 }
838 }
839
840 return nullptr;
841}
842
843void
844BaseCache::satisfyRequest(PacketPtr pkt, CacheBlk *blk, bool, bool)
845{
846 assert(pkt->isRequest());
847
848 assert(blk && blk->isValid());
849 // Occasionally this is not true... if we are a lower-level cache
850 // satisfying a string of Read and ReadEx requests from
851 // upper-level caches, a Read will mark the block as shared but we
852 // can satisfy a following ReadEx anyway since we can rely on the
853 // Read requester(s) to have buffered the ReadEx snoop and to
854 // invalidate their blocks after receiving them.
855 // assert(!pkt->needsWritable() || blk->isWritable());
856 assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
857
858 // Check RMW operations first since both isRead() and
859 // isWrite() will be true for them
860 if (pkt->cmd == MemCmd::SwapReq) {
861 if (pkt->isAtomicOp()) {
862 // extract data from cache and save it into the data field in
863 // the packet as a return value from this atomic op
864
865 int offset = tags->extractBlkOffset(pkt->getAddr());
866 uint8_t *blk_data = blk->data + offset;
867 std::memcpy(pkt->getPtr<uint8_t>(), blk_data, pkt->getSize());
868
869 // execute AMO operation
870 (*(pkt->getAtomicOp()))(blk_data);
871
872 // set block status to dirty
873 blk->status |= BlkDirty;
874 } else {
875 cmpAndSwap(blk, pkt);
876 }
877 } else if (pkt->isWrite()) {
878 // we have the block in a writable state and can go ahead,
879 // note that the line may be also be considered writable in
880 // downstream caches along the path to memory, but always
881 // Exclusive, and never Modified
882 assert(blk->isWritable());
883 // Write or WriteLine at the first cache with block in writable state
884 if (blk->checkWrite(pkt)) {
885 pkt->writeDataToBlock(blk->data, blkSize);
886 }
887 // Always mark the line as dirty (and thus transition to the
888 // Modified state) even if we are a failed StoreCond so we
889 // supply data to any snoops that have appended themselves to
890 // this cache before knowing the store will fail.
891 blk->status |= BlkDirty;
892 DPRINTF(CacheVerbose, "%s for %s (write)\n", __func__, pkt->print());
893 } else if (pkt->isRead()) {
894 if (pkt->isLLSC()) {
895 blk->trackLoadLocked(pkt);
896 }
897
898 // all read responses have a data payload
899 assert(pkt->hasRespData());
900 pkt->setDataFromBlock(blk->data, blkSize);
901 } else if (pkt->isUpgrade()) {
902 // sanity check
903 assert(!pkt->hasSharers());
904
905 if (blk->isDirty()) {
906 // we were in the Owned state, and a cache above us that
907 // has the line in Shared state needs to be made aware
908 // that the data it already has is in fact dirty
909 pkt->setCacheResponding();
910 blk->status &= ~BlkDirty;
911 }
912 } else if (pkt->isClean()) {
913 blk->status &= ~BlkDirty;
914 } else {
915 assert(pkt->isInvalidate());
916 invalidateBlock(blk);
917 DPRINTF(CacheVerbose, "%s for %s (invalidation)\n", __func__,
918 pkt->print());
919 }
920}
921
922/////////////////////////////////////////////////////
923//
924// Access path: requests coming in from the CPU side
925//
926/////////////////////////////////////////////////////
927
928bool
929BaseCache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
930 PacketList &writebacks)
931{
932 // sanity check
933 assert(pkt->isRequest());
934
935 chatty_assert(!(isReadOnly && pkt->isWrite()),
936 "Should never see a write in a read-only cache %s\n",
937 name());
938
939 // Here lat is the value passed as parameter to accessBlock() function
940 // that can modify its value.
941 blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat);
942
943 DPRINTF(Cache, "%s for %s %s\n", __func__, pkt->print(),
944 blk ? "hit " + blk->print() : "miss");
945
946 if (pkt->req->isCacheMaintenance()) {
947 // A cache maintenance operation is always forwarded to the
948 // memory below even if the block is found in dirty state.
949
950 // We defer any changes to the state of the block until we
951 // create and mark as in service the mshr for the downstream
952 // packet.
953 return false;
954 }
955
956 if (pkt->isEviction()) {
957 // We check for presence of block in above caches before issuing
958 // Writeback or CleanEvict to write buffer. Therefore the only
959 // possible cases can be of a CleanEvict packet coming from above
960 // encountering a Writeback generated in this cache peer cache and
961 // waiting in the write buffer. Cases of upper level peer caches
962 // generating CleanEvict and Writeback or simply CleanEvict and
963 // CleanEvict almost simultaneously will be caught by snoops sent out
964 // by crossbar.
965 WriteQueueEntry *wb_entry = writeBuffer.findMatch(pkt->getAddr(),
966 pkt->isSecure());
967 if (wb_entry) {
968 assert(wb_entry->getNumTargets() == 1);
969 PacketPtr wbPkt = wb_entry->getTarget()->pkt;
970 assert(wbPkt->isWriteback());
971
972 if (pkt->isCleanEviction()) {
973 // The CleanEvict and WritebackClean snoops into other
974 // peer caches of the same level while traversing the
975 // crossbar. If a copy of the block is found, the
976 // packet is deleted in the crossbar. Hence, none of
977 // the other upper level caches connected to this
978 // cache have the block, so we can clear the
979 // BLOCK_CACHED flag in the Writeback if set and
980 // discard the CleanEvict by returning true.
981 wbPkt->clearBlockCached();
982 return true;
983 } else {
984 assert(pkt->cmd == MemCmd::WritebackDirty);
985 // Dirty writeback from above trumps our clean
986 // writeback... discard here
987 // Note: markInService will remove entry from writeback buffer.
988 markInService(wb_entry);
989 delete wbPkt;
990 }
991 }
992 }
993
994 // Writeback handling is special case. We can write the block into
995 // the cache without having a writeable copy (or any copy at all).
996 if (pkt->isWriteback()) {
997 assert(blkSize == pkt->getSize());
998
999 // we could get a clean writeback while we are having
1000 // outstanding accesses to a block, do the simple thing for
1001 // now and drop the clean writeback so that we do not upset
1002 // any ordering/decisions about ownership already taken
1003 if (pkt->cmd == MemCmd::WritebackClean &&
1004 mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
1005 DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
1006 "dropping\n", pkt->getAddr());
1007 return true;
1008 }
1009
1010 if (!blk) {
1011 // need to do a replacement
1012 blk = allocateBlock(pkt, writebacks);
1013 if (!blk) {
1014 // no replaceable block available: give up, fwd to next level.
1015 incMissCount(pkt);
1016 return false;
1017 }
1018
1019 blk->status |= (BlkValid | BlkReadable);
1020 }
1021 // only mark the block dirty if we got a writeback command,
1022 // and leave it as is for a clean writeback
1023 if (pkt->cmd == MemCmd::WritebackDirty) {
1024 // TODO: the coherent cache can assert(!blk->isDirty());
1025 blk->status |= BlkDirty;
1026 }
1027 // if the packet does not have sharers, it is passing
1028 // writable, and we got the writeback in Modified or Exclusive
1029 // state, if not we are in the Owned or Shared state
1030 if (!pkt->hasSharers()) {
1031 blk->status |= BlkWritable;
1032 }
1033 // nothing else to do; writeback doesn't expect response
1034 assert(!pkt->needsResponse());
1035 pkt->writeDataToBlock(blk->data, blkSize);
1036 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
1037 incHitCount(pkt);
1038 // populate the time when the block will be ready to access.
1039 blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
1040 pkt->payloadDelay;
1041 return true;
1042 } else if (pkt->cmd == MemCmd::CleanEvict) {
1043 if (blk) {
1044 // Found the block in the tags, need to stop CleanEvict from
1045 // propagating further down the hierarchy. Returning true will
1046 // treat the CleanEvict like a satisfied write request and delete
1047 // it.
1048 return true;
1049 }
1050 // We didn't find the block here, propagate the CleanEvict further
1051 // down the memory hierarchy. Returning false will treat the CleanEvict
1052 // like a Writeback which could not find a replaceable block so has to
1053 // go to next level.
1054 return false;
1055 } else if (pkt->cmd == MemCmd::WriteClean) {
1056 // WriteClean handling is a special case. We can allocate a
1057 // block directly if it doesn't exist and we can update the
1058 // block immediately. The WriteClean transfers the ownership
1059 // of the block as well.
1060 assert(blkSize == pkt->getSize());
1061
1062 if (!blk) {
1063 if (pkt->writeThrough()) {
1064 // if this is a write through packet, we don't try to
1065 // allocate if the block is not present
1066 return false;
1067 } else {
1068 // a writeback that misses needs to allocate a new block
1069 blk = allocateBlock(pkt, writebacks);
1070 if (!blk) {
1071 // no replaceable block available: give up, fwd to
1072 // next level.
1073 incMissCount(pkt);
1074 return false;
1075 }
1076
1077 blk->status |= (BlkValid | BlkReadable);
1078 }
1079 }
1080
1081 // at this point either this is a writeback or a write-through
1082 // write clean operation and the block is already in this
1083 // cache, we need to update the data and the block flags
1084 assert(blk);
1085 // TODO: the coherent cache can assert(!blk->isDirty());
1086 if (!pkt->writeThrough()) {
1087 blk->status |= BlkDirty;
1088 }
1089 // nothing else to do; writeback doesn't expect response
1090 assert(!pkt->needsResponse());
1091 pkt->writeDataToBlock(blk->data, blkSize);
1092 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
1093
1094 incHitCount(pkt);
1095 // populate the time when the block will be ready to access.
1096 blk->whenReady = clockEdge(fillLatency) + pkt->headerDelay +
1097 pkt->payloadDelay;
1098 // if this a write-through packet it will be sent to cache
1099 // below
1100 return !pkt->writeThrough();
1101 } else if (blk && (pkt->needsWritable() ? blk->isWritable() :
1102 blk->isReadable())) {
1103 // OK to satisfy access
1104 incHitCount(pkt);
1105 satisfyRequest(pkt, blk);
1106 maintainClusivity(pkt->fromCache(), blk);
1107
1108 return true;
1109 }
1110
1111 // Can't satisfy access normally... either no block (blk == nullptr)
1112 // or have block but need writable
1113
1114 incMissCount(pkt);
1115
1116 if (!blk && pkt->isLLSC() && pkt->isWrite()) {
1117 // complete miss on store conditional... just give up now
1118 pkt->req->setExtraData(0);
1119 return true;
1120 }
1121
1122 return false;
1123}
1124
1125void
1126BaseCache::maintainClusivity(bool from_cache, CacheBlk *blk)
1127{
1128 if (from_cache && blk && blk->isValid() && !blk->isDirty() &&
1129 clusivity == Enums::mostly_excl) {
1130 // if we have responded to a cache, and our block is still
1131 // valid, but not dirty, and this cache is mostly exclusive
1132 // with respect to the cache above, drop the block
1133 invalidateBlock(blk);
1134 }
1135}
1136
1137CacheBlk*
1138BaseCache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
1139 bool allocate)
1140{
1141 assert(pkt->isResponse());
1142 Addr addr = pkt->getAddr();
1143 bool is_secure = pkt->isSecure();
1144#if TRACING_ON
1145 CacheBlk::State old_state = blk ? blk->status : 0;
1146#endif
1147
1148 // When handling a fill, we should have no writes to this line.
1149 assert(addr == pkt->getBlockAddr(blkSize));
1150 assert(!writeBuffer.findMatch(addr, is_secure));
1151
1152 if (!blk) {
1153 // better have read new data...
1154 assert(pkt->hasData() || pkt->cmd == MemCmd::InvalidateResp);
1155
1156 // need to do a replacement if allocating, otherwise we stick
1157 // with the temporary storage
1158 blk = allocate ? allocateBlock(pkt, writebacks) : nullptr;
1159
1160 if (!blk) {
1161 // No replaceable block or a mostly exclusive
1162 // cache... just use temporary storage to complete the
1163 // current request and then get rid of it
1164 assert(!tempBlock->isValid());
1165 blk = tempBlock;
1166 tempBlock->insert(addr, is_secure);
1167 DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
1168 is_secure ? "s" : "ns");
1169 }
1170
1171 // we should never be overwriting a valid block
1172 assert(!blk->isValid());
1173 } else {
1174 // existing block... probably an upgrade
1175 assert(regenerateBlkAddr(blk) == addr);
1176 assert(blk->isSecure() == is_secure);
1177 // either we're getting new data or the block should already be valid
1178 assert(pkt->hasData() || blk->isValid());
1179 // don't clear block status... if block is already dirty we
1180 // don't want to lose that
1181 }
1182
1183 blk->status |= BlkValid | BlkReadable;
1184
1185 // sanity check for whole-line writes, which should always be
1186 // marked as writable as part of the fill, and then later marked
1187 // dirty as part of satisfyRequest
1188 if (pkt->cmd == MemCmd::InvalidateResp) {
1189 assert(!pkt->hasSharers());
1190 }
1191
1192 // here we deal with setting the appropriate state of the line,
1193 // and we start by looking at the hasSharers flag, and ignore the
1194 // cacheResponding flag (normally signalling dirty data) if the
1195 // packet has sharers, thus the line is never allocated as Owned
1196 // (dirty but not writable), and always ends up being either
1197 // Shared, Exclusive or Modified, see Packet::setCacheResponding
1198 // for more details
1199 if (!pkt->hasSharers()) {
1200 // we could get a writable line from memory (rather than a
1201 // cache) even in a read-only cache, note that we set this bit
1202 // even for a read-only cache, possibly revisit this decision
1203 blk->status |= BlkWritable;
1204
1205 // check if we got this via cache-to-cache transfer (i.e., from a
1206 // cache that had the block in Modified or Owned state)
1207 if (pkt->cacheResponding()) {
1208 // we got the block in Modified state, and invalidated the
1209 // owners copy
1210 blk->status |= BlkDirty;
1211
1212 chatty_assert(!isReadOnly, "Should never see dirty snoop response "
1213 "in read-only cache %s\n", name());
1214 }
1215 }
1216
1217 DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
1218 addr, is_secure ? "s" : "ns", old_state, blk->print());
1219
1220 // if we got new data, copy it in (checking for a read response
1221 // and a response that has data is the same in the end)
1222 if (pkt->isRead()) {
1223 // sanity checks
1224 assert(pkt->hasData());
1225 assert(pkt->getSize() == blkSize);
1226
1227 pkt->writeDataToBlock(blk->data, blkSize);
1228 }
1229 // We pay for fillLatency here.
1230 blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
1231 pkt->payloadDelay;
1232
1233 return blk;
1234}
1235
1236CacheBlk*
1237BaseCache::allocateBlock(const PacketPtr pkt, PacketList &writebacks)
1238{
1239 // Get address
1240 const Addr addr = pkt->getAddr();
1241
1242 // Get secure bit
1243 const bool is_secure = pkt->isSecure();
1244
1245 // Find replacement victim
1246 std::vector<CacheBlk*> evict_blks;
1247 CacheBlk *victim = tags->findVictim(addr, is_secure, evict_blks);
1248
1249 // It is valid to return nullptr if there is no victim
1250 if (!victim)
1251 return nullptr;
1252
1253 // Print victim block's information
1254 DPRINTF(CacheRepl, "Replacement victim: %s\n", victim->print());
1255
1256 // Check for transient state allocations. If any of the entries listed
1257 // for eviction has a transient state, the allocation fails
1258 for (const auto& blk : evict_blks) {
1259 if (blk->isValid()) {
1260 Addr repl_addr = regenerateBlkAddr(blk);
1261 MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
1262 if (repl_mshr) {
1263 // must be an outstanding upgrade or clean request
1264 // on a block we're about to replace...
1265 assert((!blk->isWritable() && repl_mshr->needsWritable()) ||
1266 repl_mshr->isCleaning());
1267
1268 // too hard to replace block with transient state
1269 // allocation failed, block not inserted
1270 return nullptr;
1271 }
1272 }
1273 }
1274
1275 // The victim will be replaced by a new entry, so increase the replacement
1276 // counter if a valid block is being replaced
1277 if (victim->isValid()) {
1278 DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx "
1279 "(%s): %s\n", regenerateBlkAddr(victim),
1280 victim->isSecure() ? "s" : "ns",
1281 addr, is_secure ? "s" : "ns",
1282 victim->isDirty() ? "writeback" : "clean");
1283
1284 replacements++;
1285 }
1286
1287 // Evict valid blocks associated to this victim block
1288 for (const auto& blk : evict_blks) {
1289 if (blk->isValid()) {
1290 if (blk->wasPrefetched()) {
1291 unusedPrefetches++;
1292 }
1293
1294 evictBlock(blk, writebacks);
1295 }
1296 }
1297
1298 // Insert new block at victimized entry
1299 tags->insertBlock(addr, is_secure, pkt->req->masterId(),
1300 pkt->req->taskId(), victim);
1301
1302 return victim;
1303}
1304
1305void
1306BaseCache::invalidateBlock(CacheBlk *blk)
1307{
1308 if (blk != tempBlock)
1309 tags->invalidate(blk);
1310 blk->invalidate();
1311}
1312
1313void
1314BaseCache::evictBlock(CacheBlk *blk, PacketList &writebacks)
1315{
1316 PacketPtr pkt = evictBlock(blk);
1317 if (pkt) {
1318 writebacks.push_back(pkt);
1319 }
1320}
1321
1322PacketPtr
1323BaseCache::writebackBlk(CacheBlk *blk)
1324{
1325 chatty_assert(!isReadOnly || writebackClean,
1326 "Writeback from read-only cache");
1327 assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
1328
1329 writebacks[Request::wbMasterId]++;
1330
1331 RequestPtr req = std::make_shared<Request>(
1332 regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId);
1333
1334 if (blk->isSecure())
1335 req->setFlags(Request::SECURE);
1336
1337 req->taskId(blk->task_id);
1338
1339 PacketPtr pkt =
1340 new Packet(req, blk->isDirty() ?
1341 MemCmd::WritebackDirty : MemCmd::WritebackClean);
1342
1343 DPRINTF(Cache, "Create Writeback %s writable: %d, dirty: %d\n",
1344 pkt->print(), blk->isWritable(), blk->isDirty());
1345
1346 if (blk->isWritable()) {
1347 // not asserting shared means we pass the block in modified
1348 // state, mark our own block non-writeable
1349 blk->status &= ~BlkWritable;
1350 } else {
1351 // we are in the Owned state, tell the receiver
1352 pkt->setHasSharers();
1353 }
1354
1355 // make sure the block is not marked dirty
1356 blk->status &= ~BlkDirty;
1357
1358 pkt->allocate();
1359 pkt->setDataFromBlock(blk->data, blkSize);
1360
1361 return pkt;
1362}
1363
1364PacketPtr
1365BaseCache::writecleanBlk(CacheBlk *blk, Request::Flags dest, PacketId id)
1366{
1367 RequestPtr req = std::make_shared<Request>(
1368 regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId);
1369
1370 if (blk->isSecure()) {
1371 req->setFlags(Request::SECURE);
1372 }
1373 req->taskId(blk->task_id);
1374
1375 PacketPtr pkt = new Packet(req, MemCmd::WriteClean, blkSize, id);
1376
1377 if (dest) {
1378 req->setFlags(dest);
1379 pkt->setWriteThrough();
1380 }
1381
1382 DPRINTF(Cache, "Create %s writable: %d, dirty: %d\n", pkt->print(),
1383 blk->isWritable(), blk->isDirty());
1384
1385 if (blk->isWritable()) {
1386 // not asserting shared means we pass the block in modified
1387 // state, mark our own block non-writeable
1388 blk->status &= ~BlkWritable;
1389 } else {
1390 // we are in the Owned state, tell the receiver
1391 pkt->setHasSharers();
1392 }
1393
1394 // make sure the block is not marked dirty
1395 blk->status &= ~BlkDirty;
1396
1397 pkt->allocate();
1398 pkt->setDataFromBlock(blk->data, blkSize);
1399
1400 return pkt;
1401}
1402
1403
1404void
1405BaseCache::memWriteback()
1406{
1407 tags->forEachBlk([this](CacheBlk &blk) { writebackVisitor(blk); });
1408}
1409
1410void
1411BaseCache::memInvalidate()
1412{
1413 tags->forEachBlk([this](CacheBlk &blk) { invalidateVisitor(blk); });
1414}
1415
1416bool
1417BaseCache::isDirty() const
1418{
1419 return tags->anyBlk([](CacheBlk &blk) { return blk.isDirty(); });
1420}
1421
1422void
1423BaseCache::writebackVisitor(CacheBlk &blk)
1424{
1425 if (blk.isDirty()) {
1426 assert(blk.isValid());
1427
1428 RequestPtr request = std::make_shared<Request>(
1429 regenerateBlkAddr(&blk), blkSize, 0, Request::funcMasterId);
1430
1431 request->taskId(blk.task_id);
1432 if (blk.isSecure()) {
1433 request->setFlags(Request::SECURE);
1434 }
1435
1436 Packet packet(request, MemCmd::WriteReq);
1437 packet.dataStatic(blk.data);
1438
1439 memSidePort.sendFunctional(&packet);
1440
1441 blk.status &= ~BlkDirty;
1442 }
1443}
1444
1445void
1446BaseCache::invalidateVisitor(CacheBlk &blk)
1447{
1448 if (blk.isDirty())
1449 warn_once("Invalidating dirty cache lines. " \
1450 "Expect things to break.\n");
1451
1452 if (blk.isValid()) {
1453 assert(!blk.isDirty());
1454 invalidateBlock(&blk);
1455 }
1456}
1457
1458Tick
1459BaseCache::nextQueueReadyTime() const
1460{
1461 Tick nextReady = std::min(mshrQueue.nextReadyTime(),
1462 writeBuffer.nextReadyTime());
1463
1464 // Don't signal prefetch ready time if no MSHRs available
1465 // Will signal once enoguh MSHRs are deallocated
1466 if (prefetcher && mshrQueue.canPrefetch()) {
1467 nextReady = std::min(nextReady,
1468 prefetcher->nextPrefetchReadyTime());
1469 }
1470
1471 return nextReady;
1472}
1473
1474
1475bool
1476BaseCache::sendMSHRQueuePacket(MSHR* mshr)
1477{
1478 assert(mshr);
1479
1480 // use request from 1st target
1481 PacketPtr tgt_pkt = mshr->getTarget()->pkt;
1482
1483 DPRINTF(Cache, "%s: MSHR %s\n", __func__, tgt_pkt->print());
1484
1485 // if the cache is in write coalescing mode or (additionally) in
1486 // no allocation mode, and we have a write packet with an MSHR
1487 // that is not a whole-line write (due to incompatible flags etc),
1488 // then reset the write mode
1489 if (writeAllocator && writeAllocator->coalesce() && tgt_pkt->isWrite()) {
1490 if (!mshr->isWholeLineWrite()) {
1491 // if we are currently write coalescing, hold on the
1492 // MSHR as many cycles extra as we need to completely
1493 // write a cache line
1494 if (writeAllocator->delay(mshr->blkAddr)) {
1495 Tick delay = blkSize / tgt_pkt->getSize() * clockPeriod();
1496 DPRINTF(CacheVerbose, "Delaying pkt %s %llu ticks to allow "
1497 "for write coalescing\n", tgt_pkt->print(), delay);
1498 mshrQueue.delay(mshr, delay);
1499 return false;
1500 } else {
1501 writeAllocator->reset();
1502 }
1503 } else {
1504 writeAllocator->resetDelay(mshr->blkAddr);
1505 }
1506 }
1507
1508 CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
1509
1510 // either a prefetch that is not present upstream, or a normal
1511 // MSHR request, proceed to get the packet to send downstream
1512 PacketPtr pkt = createMissPacket(tgt_pkt, blk, mshr->needsWritable(),
1513 mshr->isWholeLineWrite());
1514
1515 mshr->isForward = (pkt == nullptr);
1516
1517 if (mshr->isForward) {
1518 // not a cache block request, but a response is expected
1519 // make copy of current packet to forward, keep current
1520 // copy for response handling
1521 pkt = new Packet(tgt_pkt, false, true);
1522 assert(!pkt->isWrite());
1523 }
1524
1525 // play it safe and append (rather than set) the sender state,
1526 // as forwarded packets may already have existing state
1527 pkt->pushSenderState(mshr);
1528
1529 if (pkt->isClean() && blk && blk->isDirty()) {
1530 // A cache clean opearation is looking for a dirty block. Mark
1531 // the packet so that the destination xbar can determine that
1532 // there will be a follow-up write packet as well.
1533 pkt->setSatisfied();
1534 }
1535
1536 if (!memSidePort.sendTimingReq(pkt)) {
1537 // we are awaiting a retry, but we
1538 // delete the packet and will be creating a new packet
1539 // when we get the opportunity
1540 delete pkt;
1541
1542 // note that we have now masked any requestBus and
1543 // schedSendEvent (we will wait for a retry before
1544 // doing anything), and this is so even if we do not
1545 // care about this packet and might override it before
1546 // it gets retried
1547 return true;
1548 } else {
1549 // As part of the call to sendTimingReq the packet is
1550 // forwarded to all neighbouring caches (and any caches
1551 // above them) as a snoop. Thus at this point we know if
1552 // any of the neighbouring caches are responding, and if
1553 // so, we know it is dirty, and we can determine if it is
1554 // being passed as Modified, making our MSHR the ordering
1555 // point
1556 bool pending_modified_resp = !pkt->hasSharers() &&
1557 pkt->cacheResponding();
1558 markInService(mshr, pending_modified_resp);
1559
1560 if (pkt->isClean() && blk && blk->isDirty()) {
1561 // A cache clean opearation is looking for a dirty
1562 // block. If a dirty block is encountered a WriteClean
1563 // will update any copies to the path to the memory
1564 // until the point of reference.
1565 DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
1566 __func__, pkt->print(), blk->print());
1567 PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(),
1568 pkt->id);
1569 PacketList writebacks;
1570 writebacks.push_back(wb_pkt);
1571 doWritebacks(writebacks, 0);
1572 }
1573
1574 return false;
1575 }
1576}
1577
1578bool
1579BaseCache::sendWriteQueuePacket(WriteQueueEntry* wq_entry)
1580{
1581 assert(wq_entry);
1582
1583 // always a single target for write queue entries
1584 PacketPtr tgt_pkt = wq_entry->getTarget()->pkt;
1585
1586 DPRINTF(Cache, "%s: write %s\n", __func__, tgt_pkt->print());
1587
1588 // forward as is, both for evictions and uncacheable writes
1589 if (!memSidePort.sendTimingReq(tgt_pkt)) {
1590 // note that we have now masked any requestBus and
1591 // schedSendEvent (we will wait for a retry before
1592 // doing anything), and this is so even if we do not
1593 // care about this packet and might override it before
1594 // it gets retried
1595 return true;
1596 } else {
1597 markInService(wq_entry);
1598 return false;
1599 }
1600}
1601
1602void
1603BaseCache::serialize(CheckpointOut &cp) const
1604{
1605 bool dirty(isDirty());
1606
1607 if (dirty) {
1608 warn("*** The cache still contains dirty data. ***\n");
1609 warn(" Make sure to drain the system using the correct flags.\n");
1610 warn(" This checkpoint will not restore correctly " \
1611 "and dirty data in the cache will be lost!\n");
1612 }
1613
1614 // Since we don't checkpoint the data in the cache, any dirty data
1615 // will be lost when restoring from a checkpoint of a system that
1616 // wasn't drained properly. Flag the checkpoint as invalid if the
1617 // cache contains dirty data.
1618 bool bad_checkpoint(dirty);
1619 SERIALIZE_SCALAR(bad_checkpoint);
1620}
1621
1622void
1623BaseCache::unserialize(CheckpointIn &cp)
1624{
1625 bool bad_checkpoint;
1626 UNSERIALIZE_SCALAR(bad_checkpoint);
1627 if (bad_checkpoint) {
1628 fatal("Restoring from checkpoints with dirty caches is not "
1629 "supported in the classic memory system. Please remove any "
1630 "caches or drain them properly before taking checkpoints.\n");
1631 }
1632}
1633
1634void
1635BaseCache::regStats()
1636{
1637 MemObject::regStats();
1638
1639 using namespace Stats;
1640
1641 // Hit statistics
1642 for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1643 MemCmd cmd(access_idx);
1644 const string &cstr = cmd.toString();
1645
1646 hits[access_idx]
1647 .init(system->maxMasters())
1648 .name(name() + "." + cstr + "_hits")
1649 .desc("number of " + cstr + " hits")
1650 .flags(total | nozero | nonan)
1651 ;
1652 for (int i = 0; i < system->maxMasters(); i++) {
1653 hits[access_idx].subname(i, system->getMasterName(i));
1654 }
1655 }
1656
1657// These macros make it easier to sum the right subset of commands and
1658// to change the subset of commands that are considered "demand" vs
1659// "non-demand"
1660#define SUM_DEMAND(s) \
1661 (s[MemCmd::ReadReq] + s[MemCmd::WriteReq] + s[MemCmd::WriteLineReq] + \
1662 s[MemCmd::ReadExReq] + s[MemCmd::ReadCleanReq] + s[MemCmd::ReadSharedReq])
1663
1664// should writebacks be included here? prior code was inconsistent...
1665#define SUM_NON_DEMAND(s) \
|