base.cc revision 13932:24f825a9a080
1/*
2 * Copyright (c) 2012-2013, 2018-2019 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),
73      queue(*_cache, *this, true, _label),
74      blocked(false), mustSendRetry(false),
75      sendRetryEvent([this]{ processSendRetry(); }, _name)
76{
77}
78
79BaseCache::BaseCache(const BaseCacheParams *p, unsigned blk_size)
80    : ClockedObject(p),
81      cpuSidePort (p->name + ".cpu_side", this, "CpuSidePort"),
82      memSidePort(p->name + ".mem_side", this, "MemSidePort"),
83      mshrQueue("MSHRs", p->mshrs, 0, p->demand_mshr_reserve), // see below
84      writeBuffer("write buffer", p->write_buffers, p->mshrs), // see below
85      tags(p->tags),
86      prefetcher(p->prefetcher),
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      sequentialAccess(p->sequential_access),
100      numTarget(p->tgts_per_mshr),
101      forwardSnoops(true),
102      clusivity(p->clusivity),
103      isReadOnly(p->is_read_only),
104      blocked(0),
105      order(0),
106      noTargetMSHR(nullptr),
107      missCount(p->max_miss_count),
108      addrRanges(p->addr_ranges.begin(), p->addr_ranges.end()),
109      system(p->system)
110{
111    // the MSHR queue has no reserve entries as we check the MSHR
112    // queue on every single allocation, whereas the write queue has
113    // as many reserve entries as we have MSHRs, since every MSHR may
114    // eventually require a writeback, and we do not check the write
115    // buffer before committing to an MSHR
116
117    // forward snoops is overridden in init() once we can query
118    // whether the connected master is actually snooping or not
119
120    tempBlock = new TempCacheBlk(blkSize);
121
122    tags->tagsInit();
123    if (prefetcher)
124        prefetcher->setCache(this);
125}
126
127BaseCache::~BaseCache()
128{
129    delete tempBlock;
130}
131
132void
133BaseCache::CacheSlavePort::setBlocked()
134{
135    assert(!blocked);
136    DPRINTF(CachePort, "Port is blocking new requests\n");
137    blocked = true;
138    // if we already scheduled a retry in this cycle, but it has not yet
139    // happened, cancel it
140    if (sendRetryEvent.scheduled()) {
141        owner.deschedule(sendRetryEvent);
142        DPRINTF(CachePort, "Port descheduled retry\n");
143        mustSendRetry = true;
144    }
145}
146
147void
148BaseCache::CacheSlavePort::clearBlocked()
149{
150    assert(blocked);
151    DPRINTF(CachePort, "Port is accepting new requests\n");
152    blocked = false;
153    if (mustSendRetry) {
154        // @TODO: need to find a better time (next cycle?)
155        owner.schedule(sendRetryEvent, curTick() + 1);
156    }
157}
158
159void
160BaseCache::CacheSlavePort::processSendRetry()
161{
162    DPRINTF(CachePort, "Port is sending retry\n");
163
164    // reset the flag and call retry
165    mustSendRetry = false;
166    sendRetryReq();
167}
168
169Addr
170BaseCache::regenerateBlkAddr(CacheBlk* blk)
171{
172    if (blk != tempBlock) {
173        return tags->regenerateBlkAddr(blk);
174    } else {
175        return tempBlock->getAddr();
176    }
177}
178
179void
180BaseCache::init()
181{
182    if (!cpuSidePort.isConnected() || !memSidePort.isConnected())
183        fatal("Cache ports on %s are not connected\n", name());
184    cpuSidePort.sendRangeChange();
185    forwardSnoops = cpuSidePort.isSnooping();
186}
187
188Port &
189BaseCache::getPort(const std::string &if_name, PortID idx)
190{
191    if (if_name == "mem_side") {
192        return memSidePort;
193    } else if (if_name == "cpu_side") {
194        return cpuSidePort;
195    }  else {
196        return ClockedObject::getPort(if_name, idx);
197    }
198}
199
200bool
201BaseCache::inRange(Addr addr) const
202{
203    for (const auto& r : addrRanges) {
204        if (r.contains(addr)) {
205            return true;
206       }
207    }
208    return false;
209}
210
211void
212BaseCache::handleTimingReqHit(PacketPtr pkt, CacheBlk *blk, Tick request_time)
213{
214    if (pkt->needsResponse()) {
215        // These delays should have been consumed by now
216        assert(pkt->headerDelay == 0);
217        assert(pkt->payloadDelay == 0);
218
219        pkt->makeTimingResponse();
220
221        // In this case we are considering request_time that takes
222        // into account the delay of the xbar, if any, and just
223        // lat, neglecting responseLatency, modelling hit latency
224        // just as the value of lat overriden by access(), which calls
225        // the calculateAccessLatency() function.
226        cpuSidePort.schedTimingResp(pkt, request_time);
227    } else {
228        DPRINTF(Cache, "%s satisfied %s, no response needed\n", __func__,
229                pkt->print());
230
231        // queue the packet for deletion, as the sending cache is
232        // still relying on it; if the block is found in access(),
233        // CleanEvict and Writeback messages will be deleted
234        // here as well
235        pendingDelete.reset(pkt);
236    }
237}
238
239void
240BaseCache::handleTimingReqMiss(PacketPtr pkt, MSHR *mshr, CacheBlk *blk,
241                               Tick forward_time, Tick request_time)
242{
243    if (writeAllocator &&
244        pkt && pkt->isWrite() && !pkt->req->isUncacheable()) {
245        writeAllocator->updateMode(pkt->getAddr(), pkt->getSize(),
246                                   pkt->getBlockAddr(blkSize));
247    }
248
249    if (mshr) {
250        /// MSHR hit
251        /// @note writebacks will be checked in getNextMSHR()
252        /// for any conflicting requests to the same block
253
254        //@todo remove hw_pf here
255
256        // Coalesce unless it was a software prefetch (see above).
257        if (pkt) {
258            assert(!pkt->isWriteback());
259            // CleanEvicts corresponding to blocks which have
260            // outstanding requests in MSHRs are simply sunk here
261            if (pkt->cmd == MemCmd::CleanEvict) {
262                pendingDelete.reset(pkt);
263            } else if (pkt->cmd == MemCmd::WriteClean) {
264                // A WriteClean should never coalesce with any
265                // outstanding cache maintenance requests.
266
267                // We use forward_time here because there is an
268                // uncached memory write, forwarded to WriteBuffer.
269                allocateWriteBuffer(pkt, forward_time);
270            } else {
271                DPRINTF(Cache, "%s coalescing MSHR for %s\n", __func__,
272                        pkt->print());
273
274                assert(pkt->req->masterId() < system->maxMasters());
275                mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
276
277                // We use forward_time here because it is the same
278                // considering new targets. We have multiple
279                // requests for the same address here. It
280                // specifies the latency to allocate an internal
281                // buffer and to schedule an event to the queued
282                // port and also takes into account the additional
283                // delay of the xbar.
284                mshr->allocateTarget(pkt, forward_time, order++,
285                                     allocOnFill(pkt->cmd));
286                if (mshr->getNumTargets() == numTarget) {
287                    noTargetMSHR = mshr;
288                    setBlocked(Blocked_NoTargets);
289                    // need to be careful with this... if this mshr isn't
290                    // ready yet (i.e. time > curTick()), we don't want to
291                    // move it ahead of mshrs that are ready
292                    // mshrQueue.moveToFront(mshr);
293                }
294            }
295        }
296    } else {
297        // no MSHR
298        assert(pkt->req->masterId() < system->maxMasters());
299        mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
300
301        if (pkt->isEviction() || pkt->cmd == MemCmd::WriteClean) {
302            // We use forward_time here because there is an
303            // writeback or writeclean, forwarded to WriteBuffer.
304            allocateWriteBuffer(pkt, forward_time);
305        } else {
306            if (blk && blk->isValid()) {
307                // If we have a write miss to a valid block, we
308                // need to mark the block non-readable.  Otherwise
309                // if we allow reads while there's an outstanding
310                // write miss, the read could return stale data
311                // out of the cache block... a more aggressive
312                // system could detect the overlap (if any) and
313                // forward data out of the MSHRs, but we don't do
314                // that yet.  Note that we do need to leave the
315                // block valid so that it stays in the cache, in
316                // case we get an upgrade response (and hence no
317                // new data) when the write miss completes.
318                // As long as CPUs do proper store/load forwarding
319                // internally, and have a sufficiently weak memory
320                // model, this is probably unnecessary, but at some
321                // point it must have seemed like we needed it...
322                assert((pkt->needsWritable() && !blk->isWritable()) ||
323                       pkt->req->isCacheMaintenance());
324                blk->status &= ~BlkReadable;
325            }
326            // Here we are using forward_time, modelling the latency of
327            // a miss (outbound) just as forwardLatency, neglecting the
328            // lookupLatency component.
329            allocateMissBuffer(pkt, forward_time);
330        }
331    }
332}
333
334void
335BaseCache::recvTimingReq(PacketPtr pkt)
336{
337    // anything that is merely forwarded pays for the forward latency and
338    // the delay provided by the crossbar
339    Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
340
341    Cycles lat;
342    CacheBlk *blk = nullptr;
343    bool satisfied = false;
344    {
345        PacketList writebacks;
346        // Note that lat is passed by reference here. The function
347        // access() will set the lat value.
348        satisfied = access(pkt, blk, lat, writebacks);
349
350        // After the evicted blocks are selected, they must be forwarded
351        // to the write buffer to ensure they logically precede anything
352        // happening below
353        doWritebacks(writebacks, clockEdge(lat + forwardLatency));
354    }
355
356    // Here we charge the headerDelay that takes into account the latencies
357    // of the bus, if the packet comes from it.
358    // The latency charged is just the value set by the access() function.
359    // In case of a hit we are neglecting response latency.
360    // In case of a miss we are neglecting forward latency.
361    Tick request_time = clockEdge(lat);
362    // Here we reset the timing of the packet.
363    pkt->headerDelay = pkt->payloadDelay = 0;
364
365    if (satisfied) {
366        // notify before anything else as later handleTimingReqHit might turn
367        // the packet in a response
368        ppHit->notify(pkt);
369
370        if (prefetcher && blk && blk->wasPrefetched()) {
371            blk->status &= ~BlkHWPrefetched;
372        }
373
374        handleTimingReqHit(pkt, blk, request_time);
375    } else {
376        handleTimingReqMiss(pkt, blk, forward_time, request_time);
377
378        ppMiss->notify(pkt);
379    }
380
381    if (prefetcher) {
382        // track time of availability of next prefetch, if any
383        Tick next_pf_time = prefetcher->nextPrefetchReadyTime();
384        if (next_pf_time != MaxTick) {
385            schedMemSideSendEvent(next_pf_time);
386        }
387    }
388}
389
390void
391BaseCache::handleUncacheableWriteResp(PacketPtr pkt)
392{
393    Tick completion_time = clockEdge(responseLatency) +
394        pkt->headerDelay + pkt->payloadDelay;
395
396    // Reset the bus additional time as it is now accounted for
397    pkt->headerDelay = pkt->payloadDelay = 0;
398
399    cpuSidePort.schedTimingResp(pkt, completion_time);
400}
401
402void
403BaseCache::recvTimingResp(PacketPtr pkt)
404{
405    assert(pkt->isResponse());
406
407    // all header delay should be paid for by the crossbar, unless
408    // this is a prefetch response from above
409    panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
410             "%s saw a non-zero packet delay\n", name());
411
412    const bool is_error = pkt->isError();
413
414    if (is_error) {
415        DPRINTF(Cache, "%s: Cache received %s with error\n", __func__,
416                pkt->print());
417    }
418
419    DPRINTF(Cache, "%s: Handling response %s\n", __func__,
420            pkt->print());
421
422    // if this is a write, we should be looking at an uncacheable
423    // write
424    if (pkt->isWrite()) {
425        assert(pkt->req->isUncacheable());
426        handleUncacheableWriteResp(pkt);
427        return;
428    }
429
430    // we have dealt with any (uncacheable) writes above, from here on
431    // we know we are dealing with an MSHR due to a miss or a prefetch
432    MSHR *mshr = dynamic_cast<MSHR*>(pkt->popSenderState());
433    assert(mshr);
434
435    if (mshr == noTargetMSHR) {
436        // we always clear at least one target
437        clearBlocked(Blocked_NoTargets);
438        noTargetMSHR = nullptr;
439    }
440
441    // Initial target is used just for stats
442    QueueEntry::Target *initial_tgt = mshr->getTarget();
443    int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
444    Tick miss_latency = curTick() - initial_tgt->recvTime;
445
446    if (pkt->req->isUncacheable()) {
447        assert(pkt->req->masterId() < system->maxMasters());
448        mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
449            miss_latency;
450    } else {
451        assert(pkt->req->masterId() < system->maxMasters());
452        mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
453            miss_latency;
454    }
455
456    PacketList writebacks;
457
458    bool is_fill = !mshr->isForward &&
459        (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp ||
460         mshr->wasWholeLineWrite);
461
462    // make sure that if the mshr was due to a whole line write then
463    // the response is an invalidation
464    assert(!mshr->wasWholeLineWrite || pkt->isInvalidate());
465
466    CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
467
468    if (is_fill && !is_error) {
469        DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
470                pkt->getAddr());
471
472        const bool allocate = (writeAllocator && mshr->wasWholeLineWrite) ?
473            writeAllocator->allocate() : mshr->allocOnFill();
474        blk = handleFill(pkt, blk, writebacks, allocate);
475        assert(blk != nullptr);
476        ppFill->notify(pkt);
477    }
478
479    if (blk && blk->isValid() && pkt->isClean() && !pkt->isInvalidate()) {
480        // The block was marked not readable while there was a pending
481        // cache maintenance operation, restore its flag.
482        blk->status |= BlkReadable;
483
484        // This was a cache clean operation (without invalidate)
485        // and we have a copy of the block already. Since there
486        // is no invalidation, we can promote targets that don't
487        // require a writable copy
488        mshr->promoteReadable();
489    }
490
491    if (blk && blk->isWritable() && !pkt->req->isCacheInvalidate()) {
492        // If at this point the referenced block is writable and the
493        // response is not a cache invalidate, we promote targets that
494        // were deferred as we couldn't guarrantee a writable copy
495        mshr->promoteWritable();
496    }
497
498    serviceMSHRTargets(mshr, pkt, blk);
499
500    if (mshr->promoteDeferredTargets()) {
501        // avoid later read getting stale data while write miss is
502        // outstanding.. see comment in timingAccess()
503        if (blk) {
504            blk->status &= ~BlkReadable;
505        }
506        mshrQueue.markPending(mshr);
507        schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
508    } else {
509        // while we deallocate an mshr from the queue we still have to
510        // check the isFull condition before and after as we might
511        // have been using the reserved entries already
512        const bool was_full = mshrQueue.isFull();
513        mshrQueue.deallocate(mshr);
514        if (was_full && !mshrQueue.isFull()) {
515            clearBlocked(Blocked_NoMSHRs);
516        }
517
518        // Request the bus for a prefetch if this deallocation freed enough
519        // MSHRs for a prefetch to take place
520        if (prefetcher && mshrQueue.canPrefetch()) {
521            Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
522                                         clockEdge());
523            if (next_pf_time != MaxTick)
524                schedMemSideSendEvent(next_pf_time);
525        }
526    }
527
528    // if we used temp block, check to see if its valid and then clear it out
529    if (blk == tempBlock && tempBlock->isValid()) {
530        evictBlock(blk, writebacks);
531    }
532
533    const Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
534    // copy writebacks to write buffer
535    doWritebacks(writebacks, forward_time);
536
537    DPRINTF(CacheVerbose, "%s: Leaving with %s\n", __func__, pkt->print());
538    delete pkt;
539}
540
541
542Tick
543BaseCache::recvAtomic(PacketPtr pkt)
544{
545    // should assert here that there are no outstanding MSHRs or
546    // writebacks... that would mean that someone used an atomic
547    // access in timing mode
548
549    // We use lookupLatency here because it is used to specify the latency
550    // to access.
551    Cycles lat = lookupLatency;
552
553    CacheBlk *blk = nullptr;
554    PacketList writebacks;
555    bool satisfied = access(pkt, blk, lat, writebacks);
556
557    if (pkt->isClean() && blk && blk->isDirty()) {
558        // A cache clean opearation is looking for a dirty
559        // block. If a dirty block is encountered a WriteClean
560        // will update any copies to the path to the memory
561        // until the point of reference.
562        DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
563                __func__, pkt->print(), blk->print());
564        PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(), pkt->id);
565        writebacks.push_back(wb_pkt);
566        pkt->setSatisfied();
567    }
568
569    // handle writebacks resulting from the access here to ensure they
570    // logically precede anything happening below
571    doWritebacksAtomic(writebacks);
572    assert(writebacks.empty());
573
574    if (!satisfied) {
575        lat += handleAtomicReqMiss(pkt, blk, writebacks);
576    }
577
578    // Note that we don't invoke the prefetcher at all in atomic mode.
579    // It's not clear how to do it properly, particularly for
580    // prefetchers that aggressively generate prefetch candidates and
581    // rely on bandwidth contention to throttle them; these will tend
582    // to pollute the cache in atomic mode since there is no bandwidth
583    // contention.  If we ever do want to enable prefetching in atomic
584    // mode, though, this is the place to do it... see timingAccess()
585    // for an example (though we'd want to issue the prefetch(es)
586    // immediately rather than calling requestMemSideBus() as we do
587    // there).
588
589    // do any writebacks resulting from the response handling
590    doWritebacksAtomic(writebacks);
591
592    // if we used temp block, check to see if its valid and if so
593    // clear it out, but only do so after the call to recvAtomic is
594    // finished so that any downstream observers (such as a snoop
595    // filter), first see the fill, and only then see the eviction
596    if (blk == tempBlock && tempBlock->isValid()) {
597        // the atomic CPU calls recvAtomic for fetch and load/store
598        // sequentuially, and we may already have a tempBlock
599        // writeback from the fetch that we have not yet sent
600        if (tempBlockWriteback) {
601            // if that is the case, write the prevoius one back, and
602            // do not schedule any new event
603            writebackTempBlockAtomic();
604        } else {
605            // the writeback/clean eviction happens after the call to
606            // recvAtomic has finished (but before any successive
607            // calls), so that the response handling from the fill is
608            // allowed to happen first
609            schedule(writebackTempBlockAtomicEvent, curTick());
610        }
611
612        tempBlockWriteback = evictBlock(blk);
613    }
614
615    if (pkt->needsResponse()) {
616        pkt->makeAtomicResponse();
617    }
618
619    return lat * clockPeriod();
620}
621
622void
623BaseCache::functionalAccess(PacketPtr pkt, bool from_cpu_side)
624{
625    Addr blk_addr = pkt->getBlockAddr(blkSize);
626    bool is_secure = pkt->isSecure();
627    CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
628    MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
629
630    pkt->pushLabel(name());
631
632    CacheBlkPrintWrapper cbpw(blk);
633
634    // Note that just because an L2/L3 has valid data doesn't mean an
635    // L1 doesn't have a more up-to-date modified copy that still
636    // needs to be found.  As a result we always update the request if
637    // we have it, but only declare it satisfied if we are the owner.
638
639    // see if we have data at all (owned or otherwise)
640    bool have_data = blk && blk->isValid()
641        && pkt->trySatisfyFunctional(&cbpw, blk_addr, is_secure, blkSize,
642                                     blk->data);
643
644    // data we have is dirty if marked as such or if we have an
645    // in-service MSHR that is pending a modified line
646    bool have_dirty =
647        have_data && (blk->isDirty() ||
648                      (mshr && mshr->inService && mshr->isPendingModified()));
649
650    bool done = have_dirty ||
651        cpuSidePort.trySatisfyFunctional(pkt) ||
652        mshrQueue.trySatisfyFunctional(pkt) ||
653        writeBuffer.trySatisfyFunctional(pkt) ||
654        memSidePort.trySatisfyFunctional(pkt);
655
656    DPRINTF(CacheVerbose, "%s: %s %s%s%s\n", __func__,  pkt->print(),
657            (blk && blk->isValid()) ? "valid " : "",
658            have_data ? "data " : "", done ? "done " : "");
659
660    // We're leaving the cache, so pop cache->name() label
661    pkt->popLabel();
662
663    if (done) {
664        pkt->makeResponse();
665    } else {
666        // if it came as a request from the CPU side then make sure it
667        // continues towards the memory side
668        if (from_cpu_side) {
669            memSidePort.sendFunctional(pkt);
670        } else if (cpuSidePort.isSnooping()) {
671            // if it came from the memory side, it must be a snoop request
672            // and we should only forward it if we are forwarding snoops
673            cpuSidePort.sendFunctionalSnoop(pkt);
674        }
675    }
676}
677
678
679void
680BaseCache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
681{
682    assert(pkt->isRequest());
683
684    uint64_t overwrite_val;
685    bool overwrite_mem;
686    uint64_t condition_val64;
687    uint32_t condition_val32;
688
689    int offset = pkt->getOffset(blkSize);
690    uint8_t *blk_data = blk->data + offset;
691
692    assert(sizeof(uint64_t) >= pkt->getSize());
693
694    overwrite_mem = true;
695    // keep a copy of our possible write value, and copy what is at the
696    // memory address into the packet
697    pkt->writeData((uint8_t *)&overwrite_val);
698    pkt->setData(blk_data);
699
700    if (pkt->req->isCondSwap()) {
701        if (pkt->getSize() == sizeof(uint64_t)) {
702            condition_val64 = pkt->req->getExtraData();
703            overwrite_mem = !std::memcmp(&condition_val64, blk_data,
704                                         sizeof(uint64_t));
705        } else if (pkt->getSize() == sizeof(uint32_t)) {
706            condition_val32 = (uint32_t)pkt->req->getExtraData();
707            overwrite_mem = !std::memcmp(&condition_val32, blk_data,
708                                         sizeof(uint32_t));
709        } else
710            panic("Invalid size for conditional read/write\n");
711    }
712
713    if (overwrite_mem) {
714        std::memcpy(blk_data, &overwrite_val, pkt->getSize());
715        blk->status |= BlkDirty;
716    }
717}
718
719QueueEntry*
720BaseCache::getNextQueueEntry()
721{
722    // Check both MSHR queue and write buffer for potential requests,
723    // note that null does not mean there is no request, it could
724    // simply be that it is not ready
725    MSHR *miss_mshr  = mshrQueue.getNext();
726    WriteQueueEntry *wq_entry = writeBuffer.getNext();
727
728    // If we got a write buffer request ready, first priority is a
729    // full write buffer, otherwise we favour the miss requests
730    if (wq_entry && (writeBuffer.isFull() || !miss_mshr)) {
731        // need to search MSHR queue for conflicting earlier miss.
732        MSHR *conflict_mshr = mshrQueue.findPending(wq_entry);
733
734        if (conflict_mshr && conflict_mshr->order < wq_entry->order) {
735            // Service misses in order until conflict is cleared.
736            return conflict_mshr;
737
738            // @todo Note that we ignore the ready time of the conflict here
739        }
740
741        // No conflicts; issue write
742        return wq_entry;
743    } else if (miss_mshr) {
744        // need to check for conflicting earlier writeback
745        WriteQueueEntry *conflict_mshr = writeBuffer.findPending(miss_mshr);
746        if (conflict_mshr) {
747            // not sure why we don't check order here... it was in the
748            // original code but commented out.
749
750            // The only way this happens is if we are
751            // doing a write and we didn't have permissions
752            // then subsequently saw a writeback (owned got evicted)
753            // We need to make sure to perform the writeback first
754            // To preserve the dirty data, then we can issue the write
755
756            // should we return wq_entry here instead?  I.e. do we
757            // have to flush writes in order?  I don't think so... not
758            // for Alpha anyway.  Maybe for x86?
759            return conflict_mshr;
760
761            // @todo Note that we ignore the ready time of the conflict here
762        }
763
764        // No conflicts; issue read
765        return miss_mshr;
766    }
767
768    // fall through... no pending requests.  Try a prefetch.
769    assert(!miss_mshr && !wq_entry);
770    if (prefetcher && mshrQueue.canPrefetch()) {
771        // If we have a miss queue slot, we can try a prefetch
772        PacketPtr pkt = prefetcher->getPacket();
773        if (pkt) {
774            Addr pf_addr = pkt->getBlockAddr(blkSize);
775            if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
776                !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
777                !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
778                // Update statistic on number of prefetches issued
779                // (hwpf_mshr_misses)
780                assert(pkt->req->masterId() < system->maxMasters());
781                mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
782
783                // allocate an MSHR and return it, note
784                // that we send the packet straight away, so do not
785                // schedule the send
786                return allocateMissBuffer(pkt, curTick(), false);
787            } else {
788                // free the request and packet
789                delete pkt;
790            }
791        }
792    }
793
794    return nullptr;
795}
796
797void
798BaseCache::satisfyRequest(PacketPtr pkt, CacheBlk *blk, bool, bool)
799{
800    assert(pkt->isRequest());
801
802    assert(blk && blk->isValid());
803    // Occasionally this is not true... if we are a lower-level cache
804    // satisfying a string of Read and ReadEx requests from
805    // upper-level caches, a Read will mark the block as shared but we
806    // can satisfy a following ReadEx anyway since we can rely on the
807    // Read requester(s) to have buffered the ReadEx snoop and to
808    // invalidate their blocks after receiving them.
809    // assert(!pkt->needsWritable() || blk->isWritable());
810    assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
811
812    // Check RMW operations first since both isRead() and
813    // isWrite() will be true for them
814    if (pkt->cmd == MemCmd::SwapReq) {
815        if (pkt->isAtomicOp()) {
816            // extract data from cache and save it into the data field in
817            // the packet as a return value from this atomic op
818            int offset = tags->extractBlkOffset(pkt->getAddr());
819            uint8_t *blk_data = blk->data + offset;
820            pkt->setData(blk_data);
821
822            // execute AMO operation
823            (*(pkt->getAtomicOp()))(blk_data);
824
825            // set block status to dirty
826            blk->status |= BlkDirty;
827        } else {
828            cmpAndSwap(blk, pkt);
829        }
830    } else if (pkt->isWrite()) {
831        // we have the block in a writable state and can go ahead,
832        // note that the line may be also be considered writable in
833        // downstream caches along the path to memory, but always
834        // Exclusive, and never Modified
835        assert(blk->isWritable());
836        // Write or WriteLine at the first cache with block in writable state
837        if (blk->checkWrite(pkt)) {
838            pkt->writeDataToBlock(blk->data, blkSize);
839        }
840        // Always mark the line as dirty (and thus transition to the
841        // Modified state) even if we are a failed StoreCond so we
842        // supply data to any snoops that have appended themselves to
843        // this cache before knowing the store will fail.
844        blk->status |= BlkDirty;
845        DPRINTF(CacheVerbose, "%s for %s (write)\n", __func__, pkt->print());
846    } else if (pkt->isRead()) {
847        if (pkt->isLLSC()) {
848            blk->trackLoadLocked(pkt);
849        }
850
851        // all read responses have a data payload
852        assert(pkt->hasRespData());
853        pkt->setDataFromBlock(blk->data, blkSize);
854    } else if (pkt->isUpgrade()) {
855        // sanity check
856        assert(!pkt->hasSharers());
857
858        if (blk->isDirty()) {
859            // we were in the Owned state, and a cache above us that
860            // has the line in Shared state needs to be made aware
861            // that the data it already has is in fact dirty
862            pkt->setCacheResponding();
863            blk->status &= ~BlkDirty;
864        }
865    } else if (pkt->isClean()) {
866        blk->status &= ~BlkDirty;
867    } else {
868        assert(pkt->isInvalidate());
869        invalidateBlock(blk);
870        DPRINTF(CacheVerbose, "%s for %s (invalidation)\n", __func__,
871                pkt->print());
872    }
873}
874
875/////////////////////////////////////////////////////
876//
877// Access path: requests coming in from the CPU side
878//
879/////////////////////////////////////////////////////
880Cycles
881BaseCache::calculateTagOnlyLatency(const uint32_t delay,
882                                   const Cycles lookup_lat) const
883{
884    // A tag-only access has to wait for the packet to arrive in order to
885    // perform the tag lookup.
886    return ticksToCycles(delay) + lookup_lat;
887}
888
889Cycles
890BaseCache::calculateAccessLatency(const CacheBlk* blk, const uint32_t delay,
891                                  const Cycles lookup_lat) const
892{
893    Cycles lat(0);
894
895    if (blk != nullptr) {
896        // As soon as the access arrives, for sequential accesses first access
897        // tags, then the data entry. In the case of parallel accesses the
898        // latency is dictated by the slowest of tag and data latencies.
899        if (sequentialAccess) {
900            lat = ticksToCycles(delay) + lookup_lat + dataLatency;
901        } else {
902            lat = ticksToCycles(delay) + std::max(lookup_lat, dataLatency);
903        }
904
905        // Check if the block to be accessed is available. If not, apply the
906        // access latency on top of when the block is ready to be accessed.
907        const Tick tick = curTick() + delay;
908        const Tick when_ready = blk->getWhenReady();
909        if (when_ready > tick &&
910            ticksToCycles(when_ready - tick) > lat) {
911            lat += ticksToCycles(when_ready - tick);
912        }
913    } else {
914        // In case of a miss, we neglect the data access in a parallel
915        // configuration (i.e., the data access will be stopped as soon as
916        // we find out it is a miss), and use the tag-only latency.
917        lat = calculateTagOnlyLatency(delay, lookup_lat);
918    }
919
920    return lat;
921}
922
923bool
924BaseCache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
925                  PacketList &writebacks)
926{
927    // sanity check
928    assert(pkt->isRequest());
929
930    chatty_assert(!(isReadOnly && pkt->isWrite()),
931                  "Should never see a write in a read-only cache %s\n",
932                  name());
933
934    // Access block in the tags
935    Cycles tag_latency(0);
936    blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), tag_latency);
937
938    DPRINTF(Cache, "%s for %s %s\n", __func__, pkt->print(),
939            blk ? "hit " + blk->print() : "miss");
940
941    if (pkt->req->isCacheMaintenance()) {
942        // A cache maintenance operation is always forwarded to the
943        // memory below even if the block is found in dirty state.
944
945        // We defer any changes to the state of the block until we
946        // create and mark as in service the mshr for the downstream
947        // packet.
948
949        // Calculate access latency on top of when the packet arrives. This
950        // takes into account the bus delay.
951        lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
952
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
983                // A clean evict does not need to access the data array
984                lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
985
986                return true;
987            } else {
988                assert(pkt->cmd == MemCmd::WritebackDirty);
989                // Dirty writeback from above trumps our clean
990                // writeback... discard here
991                // Note: markInService will remove entry from writeback buffer.
992                markInService(wb_entry);
993                delete wbPkt;
994            }
995        }
996    }
997
998    // Writeback handling is special case.  We can write the block into
999    // the cache without having a writeable copy (or any copy at all).
1000    if (pkt->isWriteback()) {
1001        assert(blkSize == pkt->getSize());
1002
1003        // we could get a clean writeback while we are having
1004        // outstanding accesses to a block, do the simple thing for
1005        // now and drop the clean writeback so that we do not upset
1006        // any ordering/decisions about ownership already taken
1007        if (pkt->cmd == MemCmd::WritebackClean &&
1008            mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
1009            DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
1010                    "dropping\n", pkt->getAddr());
1011
1012            // A writeback searches for the block, then writes the data.
1013            // As the writeback is being dropped, the data is not touched,
1014            // and we just had to wait for the time to find a match in the
1015            // MSHR. As of now assume a mshr queue search takes as long as
1016            // a tag lookup for simplicity.
1017            lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
1018
1019            return true;
1020        }
1021
1022        if (!blk) {
1023            // need to do a replacement
1024            blk = allocateBlock(pkt, writebacks);
1025            if (!blk) {
1026                // no replaceable block available: give up, fwd to next level.
1027                incMissCount(pkt);
1028
1029                // A writeback searches for the block, then writes the data.
1030                // As the block could not be found, it was a tag-only access.
1031                lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
1032
1033                return false;
1034            }
1035
1036            blk->status |= BlkReadable;
1037        }
1038        // only mark the block dirty if we got a writeback command,
1039        // and leave it as is for a clean writeback
1040        if (pkt->cmd == MemCmd::WritebackDirty) {
1041            // TODO: the coherent cache can assert(!blk->isDirty());
1042            blk->status |= BlkDirty;
1043        }
1044        // if the packet does not have sharers, it is passing
1045        // writable, and we got the writeback in Modified or Exclusive
1046        // state, if not we are in the Owned or Shared state
1047        if (!pkt->hasSharers()) {
1048            blk->status |= BlkWritable;
1049        }
1050        // nothing else to do; writeback doesn't expect response
1051        assert(!pkt->needsResponse());
1052        pkt->writeDataToBlock(blk->data, blkSize);
1053        DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
1054        incHitCount(pkt);
1055
1056        // A writeback searches for the block, then writes the data
1057        lat = calculateAccessLatency(blk, pkt->headerDelay, tag_latency);
1058
1059        // When the packet metadata arrives, the tag lookup will be done while
1060        // the payload is arriving. Then the block will be ready to access as
1061        // soon as the fill is done
1062        blk->setWhenReady(clockEdge(fillLatency) + pkt->headerDelay +
1063            std::max(cyclesToTicks(tag_latency), (uint64_t)pkt->payloadDelay));
1064
1065        return true;
1066    } else if (pkt->cmd == MemCmd::CleanEvict) {
1067        // A CleanEvict does not need to access the data array
1068        lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
1069
1070        if (blk) {
1071            // Found the block in the tags, need to stop CleanEvict from
1072            // propagating further down the hierarchy. Returning true will
1073            // treat the CleanEvict like a satisfied write request and delete
1074            // it.
1075            return true;
1076        }
1077        // We didn't find the block here, propagate the CleanEvict further
1078        // down the memory hierarchy. Returning false will treat the CleanEvict
1079        // like a Writeback which could not find a replaceable block so has to
1080        // go to next level.
1081        return false;
1082    } else if (pkt->cmd == MemCmd::WriteClean) {
1083        // WriteClean handling is a special case. We can allocate a
1084        // block directly if it doesn't exist and we can update the
1085        // block immediately. The WriteClean transfers the ownership
1086        // of the block as well.
1087        assert(blkSize == pkt->getSize());
1088
1089        if (!blk) {
1090            if (pkt->writeThrough()) {
1091                // A writeback searches for the block, then writes the data.
1092                // As the block could not be found, it was a tag-only access.
1093                lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
1094
1095                // if this is a write through packet, we don't try to
1096                // allocate if the block is not present
1097                return false;
1098            } else {
1099                // a writeback that misses needs to allocate a new block
1100                blk = allocateBlock(pkt, writebacks);
1101                if (!blk) {
1102                    // no replaceable block available: give up, fwd to
1103                    // next level.
1104                    incMissCount(pkt);
1105
1106                    // A writeback searches for the block, then writes the
1107                    // data. As the block could not be found, it was a tag-only
1108                    // access.
1109                    lat = calculateTagOnlyLatency(pkt->headerDelay,
1110                                                  tag_latency);
1111
1112                    return false;
1113                }
1114
1115                blk->status |= BlkReadable;
1116            }
1117        }
1118
1119        // at this point either this is a writeback or a write-through
1120        // write clean operation and the block is already in this
1121        // cache, we need to update the data and the block flags
1122        assert(blk);
1123        // TODO: the coherent cache can assert(!blk->isDirty());
1124        if (!pkt->writeThrough()) {
1125            blk->status |= BlkDirty;
1126        }
1127        // nothing else to do; writeback doesn't expect response
1128        assert(!pkt->needsResponse());
1129        pkt->writeDataToBlock(blk->data, blkSize);
1130        DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
1131
1132        incHitCount(pkt);
1133
1134        // A writeback searches for the block, then writes the data
1135        lat = calculateAccessLatency(blk, pkt->headerDelay, tag_latency);
1136
1137        // When the packet metadata arrives, the tag lookup will be done while
1138        // the payload is arriving. Then the block will be ready to access as
1139        // soon as the fill is done
1140        blk->setWhenReady(clockEdge(fillLatency) + pkt->headerDelay +
1141            std::max(cyclesToTicks(tag_latency), (uint64_t)pkt->payloadDelay));
1142
1143        // if this a write-through packet it will be sent to cache
1144        // below
1145        return !pkt->writeThrough();
1146    } else if (blk && (pkt->needsWritable() ? blk->isWritable() :
1147                       blk->isReadable())) {
1148        // OK to satisfy access
1149        incHitCount(pkt);
1150
1151        // Calculate access latency based on the need to access the data array
1152        if (pkt->isRead() || pkt->isWrite()) {
1153            lat = calculateAccessLatency(blk, pkt->headerDelay, tag_latency);
1154        } else {
1155            lat = calculateTagOnlyLatency(pkt->headerDelay, tag_latency);
1156        }
1157
1158        satisfyRequest(pkt, blk);
1159        maintainClusivity(pkt->fromCache(), blk);
1160
1161        return true;
1162    }
1163
1164    // Can't satisfy access normally... either no block (blk == nullptr)
1165    // or have block but need writable
1166
1167    incMissCount(pkt);
1168
1169    lat = calculateAccessLatency(blk, pkt->headerDelay, tag_latency);
1170
1171    if (!blk && pkt->isLLSC() && pkt->isWrite()) {
1172        // complete miss on store conditional... just give up now
1173        pkt->req->setExtraData(0);
1174        return true;
1175    }
1176
1177    return false;
1178}
1179
1180void
1181BaseCache::maintainClusivity(bool from_cache, CacheBlk *blk)
1182{
1183    if (from_cache && blk && blk->isValid() && !blk->isDirty() &&
1184        clusivity == Enums::mostly_excl) {
1185        // if we have responded to a cache, and our block is still
1186        // valid, but not dirty, and this cache is mostly exclusive
1187        // with respect to the cache above, drop the block
1188        invalidateBlock(blk);
1189    }
1190}
1191
1192CacheBlk*
1193BaseCache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
1194                      bool allocate)
1195{
1196    assert(pkt->isResponse());
1197    Addr addr = pkt->getAddr();
1198    bool is_secure = pkt->isSecure();
1199#if TRACING_ON
1200    CacheBlk::State old_state = blk ? blk->status : 0;
1201#endif
1202
1203    // When handling a fill, we should have no writes to this line.
1204    assert(addr == pkt->getBlockAddr(blkSize));
1205    assert(!writeBuffer.findMatch(addr, is_secure));
1206
1207    if (!blk) {
1208        // better have read new data...
1209        assert(pkt->hasData() || pkt->cmd == MemCmd::InvalidateResp);
1210
1211        // need to do a replacement if allocating, otherwise we stick
1212        // with the temporary storage
1213        blk = allocate ? allocateBlock(pkt, writebacks) : nullptr;
1214
1215        if (!blk) {
1216            // No replaceable block or a mostly exclusive
1217            // cache... just use temporary storage to complete the
1218            // current request and then get rid of it
1219            blk = tempBlock;
1220            tempBlock->insert(addr, is_secure);
1221            DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
1222                    is_secure ? "s" : "ns");
1223        }
1224    } else {
1225        // existing block... probably an upgrade
1226        // don't clear block status... if block is already dirty we
1227        // don't want to lose that
1228    }
1229
1230    // Block is guaranteed to be valid at this point
1231    assert(blk->isValid());
1232    assert(blk->isSecure() == is_secure);
1233    assert(regenerateBlkAddr(blk) == addr);
1234
1235    blk->status |= BlkReadable;
1236
1237    // sanity check for whole-line writes, which should always be
1238    // marked as writable as part of the fill, and then later marked
1239    // dirty as part of satisfyRequest
1240    if (pkt->cmd == MemCmd::InvalidateResp) {
1241        assert(!pkt->hasSharers());
1242    }
1243
1244    // here we deal with setting the appropriate state of the line,
1245    // and we start by looking at the hasSharers flag, and ignore the
1246    // cacheResponding flag (normally signalling dirty data) if the
1247    // packet has sharers, thus the line is never allocated as Owned
1248    // (dirty but not writable), and always ends up being either
1249    // Shared, Exclusive or Modified, see Packet::setCacheResponding
1250    // for more details
1251    if (!pkt->hasSharers()) {
1252        // we could get a writable line from memory (rather than a
1253        // cache) even in a read-only cache, note that we set this bit
1254        // even for a read-only cache, possibly revisit this decision
1255        blk->status |= BlkWritable;
1256
1257        // check if we got this via cache-to-cache transfer (i.e., from a
1258        // cache that had the block in Modified or Owned state)
1259        if (pkt->cacheResponding()) {
1260            // we got the block in Modified state, and invalidated the
1261            // owners copy
1262            blk->status |= BlkDirty;
1263
1264            chatty_assert(!isReadOnly, "Should never see dirty snoop response "
1265                          "in read-only cache %s\n", name());
1266
1267        } else if (pkt->cmd.isSWPrefetch() && pkt->needsWritable()) {
1268            // All other copies of the block were invalidated and we
1269            // have an exclusive copy.
1270
1271            // The coherence protocol assumes that if we fetched an
1272            // exclusive copy of the block, we have the intention to
1273            // modify it. Therefore the MSHR for the PrefetchExReq has
1274            // been the point of ordering and this cache has commited
1275            // to respond to snoops for the block.
1276            //
1277            // In most cases this is true anyway - a PrefetchExReq
1278            // will be followed by a WriteReq. However, if that
1279            // doesn't happen, the block is not marked as dirty and
1280            // the cache doesn't respond to snoops that has committed
1281            // to do so.
1282            //
1283            // To avoid deadlocks in cases where there is a snoop
1284            // between the PrefetchExReq and the expected WriteReq, we
1285            // proactively mark the block as Dirty.
1286
1287            blk->status |= BlkDirty;
1288
1289            panic_if(!isReadOnly, "Prefetch exclusive requests from read-only "
1290                     "cache %s\n", name());
1291        }
1292    }
1293
1294    DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
1295            addr, is_secure ? "s" : "ns", old_state, blk->print());
1296
1297    // if we got new data, copy it in (checking for a read response
1298    // and a response that has data is the same in the end)
1299    if (pkt->isRead()) {
1300        // sanity checks
1301        assert(pkt->hasData());
1302        assert(pkt->getSize() == blkSize);
1303
1304        pkt->writeDataToBlock(blk->data, blkSize);
1305    }
1306    // The block will be ready when the payload arrives and the fill is done
1307    blk->setWhenReady(clockEdge(fillLatency) + pkt->headerDelay +
1308                      pkt->payloadDelay);
1309
1310    return blk;
1311}
1312
1313CacheBlk*
1314BaseCache::allocateBlock(const PacketPtr pkt, PacketList &writebacks)
1315{
1316    // Get address
1317    const Addr addr = pkt->getAddr();
1318
1319    // Get secure bit
1320    const bool is_secure = pkt->isSecure();
1321
1322    // Find replacement victim
1323    std::vector<CacheBlk*> evict_blks;
1324    CacheBlk *victim = tags->findVictim(addr, is_secure, evict_blks);
1325
1326    // It is valid to return nullptr if there is no victim
1327    if (!victim)
1328        return nullptr;
1329
1330    // Print victim block's information
1331    DPRINTF(CacheRepl, "Replacement victim: %s\n", victim->print());
1332
1333    // Check for transient state allocations. If any of the entries listed
1334    // for eviction has a transient state, the allocation fails
1335    bool replacement = false;
1336    for (const auto& blk : evict_blks) {
1337        if (blk->isValid()) {
1338            replacement = true;
1339
1340            Addr repl_addr = regenerateBlkAddr(blk);
1341            MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
1342            if (repl_mshr) {
1343                // must be an outstanding upgrade or clean request
1344                // on a block we're about to replace...
1345                assert((!blk->isWritable() && repl_mshr->needsWritable()) ||
1346                       repl_mshr->isCleaning());
1347
1348                // too hard to replace block with transient state
1349                // allocation failed, block not inserted
1350                return nullptr;
1351            }
1352        }
1353    }
1354
1355    // The victim will be replaced by a new entry, so increase the replacement
1356    // counter if a valid block is being replaced
1357    if (replacement) {
1358        // Evict valid blocks associated to this victim block
1359        for (const auto& blk : evict_blks) {
1360            if (blk->isValid()) {
1361                DPRINTF(CacheRepl, "Evicting %s (%#llx) to make room for " \
1362                        "%#llx (%s)\n", blk->print(), regenerateBlkAddr(blk),
1363                        addr, is_secure);
1364
1365                if (blk->wasPrefetched()) {
1366                    unusedPrefetches++;
1367                }
1368
1369                evictBlock(blk, writebacks);
1370            }
1371        }
1372
1373        replacements++;
1374    }
1375
1376    // Insert new block at victimized entry
1377    tags->insertBlock(pkt, victim);
1378
1379    return victim;
1380}
1381
1382void
1383BaseCache::invalidateBlock(CacheBlk *blk)
1384{
1385    // If handling a block present in the Tags, let it do its invalidation
1386    // process, which will update stats and invalidate the block itself
1387    if (blk != tempBlock) {
1388        tags->invalidate(blk);
1389    } else {
1390        tempBlock->invalidate();
1391    }
1392}
1393
1394void
1395BaseCache::evictBlock(CacheBlk *blk, PacketList &writebacks)
1396{
1397    PacketPtr pkt = evictBlock(blk);
1398    if (pkt) {
1399        writebacks.push_back(pkt);
1400    }
1401}
1402
1403PacketPtr
1404BaseCache::writebackBlk(CacheBlk *blk)
1405{
1406    chatty_assert(!isReadOnly || writebackClean,
1407                  "Writeback from read-only cache");
1408    assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
1409
1410    writebacks[Request::wbMasterId]++;
1411
1412    RequestPtr req = std::make_shared<Request>(
1413        regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId);
1414
1415    if (blk->isSecure())
1416        req->setFlags(Request::SECURE);
1417
1418    req->taskId(blk->task_id);
1419
1420    PacketPtr pkt =
1421        new Packet(req, blk->isDirty() ?
1422                   MemCmd::WritebackDirty : MemCmd::WritebackClean);
1423
1424    DPRINTF(Cache, "Create Writeback %s writable: %d, dirty: %d\n",
1425            pkt->print(), blk->isWritable(), blk->isDirty());
1426
1427    if (blk->isWritable()) {
1428        // not asserting shared means we pass the block in modified
1429        // state, mark our own block non-writeable
1430        blk->status &= ~BlkWritable;
1431    } else {
1432        // we are in the Owned state, tell the receiver
1433        pkt->setHasSharers();
1434    }
1435
1436    // make sure the block is not marked dirty
1437    blk->status &= ~BlkDirty;
1438
1439    pkt->allocate();
1440    pkt->setDataFromBlock(blk->data, blkSize);
1441
1442    return pkt;
1443}
1444
1445PacketPtr
1446BaseCache::writecleanBlk(CacheBlk *blk, Request::Flags dest, PacketId id)
1447{
1448    RequestPtr req = std::make_shared<Request>(
1449        regenerateBlkAddr(blk), blkSize, 0, Request::wbMasterId);
1450
1451    if (blk->isSecure()) {
1452        req->setFlags(Request::SECURE);
1453    }
1454    req->taskId(blk->task_id);
1455
1456    PacketPtr pkt = new Packet(req, MemCmd::WriteClean, blkSize, id);
1457
1458    if (dest) {
1459        req->setFlags(dest);
1460        pkt->setWriteThrough();
1461    }
1462
1463    DPRINTF(Cache, "Create %s writable: %d, dirty: %d\n", pkt->print(),
1464            blk->isWritable(), blk->isDirty());
1465
1466    if (blk->isWritable()) {
1467        // not asserting shared means we pass the block in modified
1468        // state, mark our own block non-writeable
1469        blk->status &= ~BlkWritable;
1470    } else {
1471        // we are in the Owned state, tell the receiver
1472        pkt->setHasSharers();
1473    }
1474
1475    // make sure the block is not marked dirty
1476    blk->status &= ~BlkDirty;
1477
1478    pkt->allocate();
1479    pkt->setDataFromBlock(blk->data, blkSize);
1480
1481    return pkt;
1482}
1483
1484
1485void
1486BaseCache::memWriteback()
1487{
1488    tags->forEachBlk([this](CacheBlk &blk) { writebackVisitor(blk); });
1489}
1490
1491void
1492BaseCache::memInvalidate()
1493{
1494    tags->forEachBlk([this](CacheBlk &blk) { invalidateVisitor(blk); });
1495}
1496
1497bool
1498BaseCache::isDirty() const
1499{
1500    return tags->anyBlk([](CacheBlk &blk) { return blk.isDirty(); });
1501}
1502
1503bool
1504BaseCache::coalesce() const
1505{
1506    return writeAllocator && writeAllocator->coalesce();
1507}
1508
1509void
1510BaseCache::writebackVisitor(CacheBlk &blk)
1511{
1512    if (blk.isDirty()) {
1513        assert(blk.isValid());
1514
1515        RequestPtr request = std::make_shared<Request>(
1516            regenerateBlkAddr(&blk), blkSize, 0, Request::funcMasterId);
1517
1518        request->taskId(blk.task_id);
1519        if (blk.isSecure()) {
1520            request->setFlags(Request::SECURE);
1521        }
1522
1523        Packet packet(request, MemCmd::WriteReq);
1524        packet.dataStatic(blk.data);
1525
1526        memSidePort.sendFunctional(&packet);
1527
1528        blk.status &= ~BlkDirty;
1529    }
1530}
1531
1532void
1533BaseCache::invalidateVisitor(CacheBlk &blk)
1534{
1535    if (blk.isDirty())
1536        warn_once("Invalidating dirty cache lines. " \
1537                  "Expect things to break.\n");
1538
1539    if (blk.isValid()) {
1540        assert(!blk.isDirty());
1541        invalidateBlock(&blk);
1542    }
1543}
1544
1545Tick
1546BaseCache::nextQueueReadyTime() const
1547{
1548    Tick nextReady = std::min(mshrQueue.nextReadyTime(),
1549                              writeBuffer.nextReadyTime());
1550
1551    // Don't signal prefetch ready time if no MSHRs available
1552    // Will signal once enoguh MSHRs are deallocated
1553    if (prefetcher && mshrQueue.canPrefetch()) {
1554        nextReady = std::min(nextReady,
1555                             prefetcher->nextPrefetchReadyTime());
1556    }
1557
1558    return nextReady;
1559}
1560
1561
1562bool
1563BaseCache::sendMSHRQueuePacket(MSHR* mshr)
1564{
1565    assert(mshr);
1566
1567    // use request from 1st target
1568    PacketPtr tgt_pkt = mshr->getTarget()->pkt;
1569
1570    DPRINTF(Cache, "%s: MSHR %s\n", __func__, tgt_pkt->print());
1571
1572    // if the cache is in write coalescing mode or (additionally) in
1573    // no allocation mode, and we have a write packet with an MSHR
1574    // that is not a whole-line write (due to incompatible flags etc),
1575    // then reset the write mode
1576    if (writeAllocator && writeAllocator->coalesce() && tgt_pkt->isWrite()) {
1577        if (!mshr->isWholeLineWrite()) {
1578            // if we are currently write coalescing, hold on the
1579            // MSHR as many cycles extra as we need to completely
1580            // write a cache line
1581            if (writeAllocator->delay(mshr->blkAddr)) {
1582                Tick delay = blkSize / tgt_pkt->getSize() * clockPeriod();
1583                DPRINTF(CacheVerbose, "Delaying pkt %s %llu ticks to allow "
1584                        "for write coalescing\n", tgt_pkt->print(), delay);
1585                mshrQueue.delay(mshr, delay);
1586                return false;
1587            } else {
1588                writeAllocator->reset();
1589            }
1590        } else {
1591            writeAllocator->resetDelay(mshr->blkAddr);
1592        }
1593    }
1594
1595    CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
1596
1597    // either a prefetch that is not present upstream, or a normal
1598    // MSHR request, proceed to get the packet to send downstream
1599    PacketPtr pkt = createMissPacket(tgt_pkt, blk, mshr->needsWritable(),
1600                                     mshr->isWholeLineWrite());
1601
1602    mshr->isForward = (pkt == nullptr);
1603
1604    if (mshr->isForward) {
1605        // not a cache block request, but a response is expected
1606        // make copy of current packet to forward, keep current
1607        // copy for response handling
1608        pkt = new Packet(tgt_pkt, false, true);
1609        assert(!pkt->isWrite());
1610    }
1611
1612    // play it safe and append (rather than set) the sender state,
1613    // as forwarded packets may already have existing state
1614    pkt->pushSenderState(mshr);
1615
1616    if (pkt->isClean() && blk && blk->isDirty()) {
1617        // A cache clean opearation is looking for a dirty block. Mark
1618        // the packet so that the destination xbar can determine that
1619        // there will be a follow-up write packet as well.
1620        pkt->setSatisfied();
1621    }
1622
1623    if (!memSidePort.sendTimingReq(pkt)) {
1624        // we are awaiting a retry, but we
1625        // delete the packet and will be creating a new packet
1626        // when we get the opportunity
1627        delete pkt;
1628
1629        // note that we have now masked any requestBus and
1630        // schedSendEvent (we will wait for a retry before
1631        // doing anything), and this is so even if we do not
1632        // care about this packet and might override it before
1633        // it gets retried
1634        return true;
1635    } else {
1636        // As part of the call to sendTimingReq the packet is
1637        // forwarded to all neighbouring caches (and any caches
1638        // above them) as a snoop. Thus at this point we know if
1639        // any of the neighbouring caches are responding, and if
1640        // so, we know it is dirty, and we can determine if it is
1641        // being passed as Modified, making our MSHR the ordering
1642        // point
1643        bool pending_modified_resp = !pkt->hasSharers() &&
1644            pkt->cacheResponding();
1645        markInService(mshr, pending_modified_resp);
1646
1647        if (pkt->isClean() && blk && blk->isDirty()) {
1648            // A cache clean opearation is looking for a dirty
1649            // block. If a dirty block is encountered a WriteClean
1650            // will update any copies to the path to the memory
1651            // until the point of reference.
1652            DPRINTF(CacheVerbose, "%s: packet %s found block: %s\n",
1653                    __func__, pkt->print(), blk->print());
1654            PacketPtr wb_pkt = writecleanBlk(blk, pkt->req->getDest(),
1655                                             pkt->id);
1656            PacketList writebacks;
1657            writebacks.push_back(wb_pkt);
1658            doWritebacks(writebacks, 0);
1659        }
1660
1661        return false;
1662    }
1663}
1664
1665bool
1666BaseCache::sendWriteQueuePacket(WriteQueueEntry* wq_entry)
1667{
1668    assert(wq_entry);
1669
1670    // always a single target for write queue entries
1671    PacketPtr tgt_pkt = wq_entry->getTarget()->pkt;
1672
1673    DPRINTF(Cache, "%s: write %s\n", __func__, tgt_pkt->print());
1674
1675    // forward as is, both for evictions and uncacheable writes
1676    if (!memSidePort.sendTimingReq(tgt_pkt)) {
1677        // note that we have now masked any requestBus and
1678        // schedSendEvent (we will wait for a retry before
1679        // doing anything), and this is so even if we do not
1680        // care about this packet and might override it before
1681        // it gets retried
1682        return true;
1683    } else {
1684        markInService(wq_entry);
1685        return false;
1686    }
1687}
1688
1689void
1690BaseCache::serialize(CheckpointOut &cp) const
1691{
1692    bool dirty(isDirty());
1693
1694    if (dirty) {
1695        warn("*** The cache still contains dirty data. ***\n");
1696        warn("    Make sure to drain the system using the correct flags.\n");
1697        warn("    This checkpoint will not restore correctly " \
1698             "and dirty data in the cache will be lost!\n");
1699    }
1700
1701    // Since we don't checkpoint the data in the cache, any dirty data
1702    // will be lost when restoring from a checkpoint of a system that
1703    // wasn't drained properly. Flag the checkpoint as invalid if the
1704    // cache contains dirty data.
1705    bool bad_checkpoint(dirty);
1706    SERIALIZE_SCALAR(bad_checkpoint);
1707}
1708
1709void
1710BaseCache::unserialize(CheckpointIn &cp)
1711{
1712    bool bad_checkpoint;
1713    UNSERIALIZE_SCALAR(bad_checkpoint);
1714    if (bad_checkpoint) {
1715        fatal("Restoring from checkpoints with dirty caches is not "
1716              "supported in the classic memory system. Please remove any "
1717              "caches or drain them properly before taking checkpoints.\n");
1718    }
1719}
1720
1721void
1722BaseCache::regStats()
1723{
1724    ClockedObject::regStats();
1725
1726    using namespace Stats;
1727
1728    // Hit statistics
1729    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1730        MemCmd cmd(access_idx);
1731        const string &cstr = cmd.toString();
1732
1733        hits[access_idx]
1734            .init(system->maxMasters())
1735            .name(name() + "." + cstr + "_hits")
1736            .desc("number of " + cstr + " hits")
1737            .flags(total | nozero | nonan)
1738            ;
1739        for (int i = 0; i < system->maxMasters(); i++) {
1740            hits[access_idx].subname(i, system->getMasterName(i));
1741        }
1742    }
1743
1744// These macros make it easier to sum the right subset of commands and
1745// to change the subset of commands that are considered "demand" vs
1746// "non-demand"
1747#define SUM_DEMAND(s) \
1748    (s[MemCmd::ReadReq] + s[MemCmd::WriteReq] + s[MemCmd::WriteLineReq] + \
1749     s[MemCmd::ReadExReq] + s[MemCmd::ReadCleanReq] + s[MemCmd::ReadSharedReq])
1750
1751// should writebacks be included here?  prior code was inconsistent...
1752#define SUM_NON_DEMAND(s) \
1753    (s[MemCmd::SoftPFReq] + s[MemCmd::HardPFReq] + s[MemCmd::SoftPFExReq])
1754
1755    demandHits
1756        .name(name() + ".demand_hits")
1757        .desc("number of demand (read+write) hits")
1758        .flags(total | nozero | nonan)
1759        ;
1760    demandHits = SUM_DEMAND(hits);
1761    for (int i = 0; i < system->maxMasters(); i++) {
1762        demandHits.subname(i, system->getMasterName(i));
1763    }
1764
1765    overallHits
1766        .name(name() + ".overall_hits")
1767        .desc("number of overall hits")
1768        .flags(total | nozero | nonan)
1769        ;
1770    overallHits = demandHits + SUM_NON_DEMAND(hits);
1771    for (int i = 0; i < system->maxMasters(); i++) {
1772        overallHits.subname(i, system->getMasterName(i));
1773    }
1774
1775    // Miss statistics
1776    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1777        MemCmd cmd(access_idx);
1778        const string &cstr = cmd.toString();
1779
1780        misses[access_idx]
1781            .init(system->maxMasters())
1782            .name(name() + "." + cstr + "_misses")
1783            .desc("number of " + cstr + " misses")
1784            .flags(total | nozero | nonan)
1785            ;
1786        for (int i = 0; i < system->maxMasters(); i++) {
1787            misses[access_idx].subname(i, system->getMasterName(i));
1788        }
1789    }
1790
1791    demandMisses
1792        .name(name() + ".demand_misses")
1793        .desc("number of demand (read+write) misses")
1794        .flags(total | nozero | nonan)
1795        ;
1796    demandMisses = SUM_DEMAND(misses);
1797    for (int i = 0; i < system->maxMasters(); i++) {
1798        demandMisses.subname(i, system->getMasterName(i));
1799    }
1800
1801    overallMisses
1802        .name(name() + ".overall_misses")
1803        .desc("number of overall misses")
1804        .flags(total | nozero | nonan)
1805        ;
1806    overallMisses = demandMisses + SUM_NON_DEMAND(misses);
1807    for (int i = 0; i < system->maxMasters(); i++) {
1808        overallMisses.subname(i, system->getMasterName(i));
1809    }
1810
1811    // Miss latency statistics
1812    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1813        MemCmd cmd(access_idx);
1814        const string &cstr = cmd.toString();
1815
1816        missLatency[access_idx]
1817            .init(system->maxMasters())
1818            .name(name() + "." + cstr + "_miss_latency")
1819            .desc("number of " + cstr + " miss cycles")
1820            .flags(total | nozero | nonan)
1821            ;
1822        for (int i = 0; i < system->maxMasters(); i++) {
1823            missLatency[access_idx].subname(i, system->getMasterName(i));
1824        }
1825    }
1826
1827    demandMissLatency
1828        .name(name() + ".demand_miss_latency")
1829        .desc("number of demand (read+write) miss cycles")
1830        .flags(total | nozero | nonan)
1831        ;
1832    demandMissLatency = SUM_DEMAND(missLatency);
1833    for (int i = 0; i < system->maxMasters(); i++) {
1834        demandMissLatency.subname(i, system->getMasterName(i));
1835    }
1836
1837    overallMissLatency
1838        .name(name() + ".overall_miss_latency")
1839        .desc("number of overall miss cycles")
1840        .flags(total | nozero | nonan)
1841        ;
1842    overallMissLatency = demandMissLatency + SUM_NON_DEMAND(missLatency);
1843    for (int i = 0; i < system->maxMasters(); i++) {
1844        overallMissLatency.subname(i, system->getMasterName(i));
1845    }
1846
1847    // access formulas
1848    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1849        MemCmd cmd(access_idx);
1850        const string &cstr = cmd.toString();
1851
1852        accesses[access_idx]
1853            .name(name() + "." + cstr + "_accesses")
1854            .desc("number of " + cstr + " accesses(hits+misses)")
1855            .flags(total | nozero | nonan)
1856            ;
1857        accesses[access_idx] = hits[access_idx] + misses[access_idx];
1858
1859        for (int i = 0; i < system->maxMasters(); i++) {
1860            accesses[access_idx].subname(i, system->getMasterName(i));
1861        }
1862    }
1863
1864    demandAccesses
1865        .name(name() + ".demand_accesses")
1866        .desc("number of demand (read+write) accesses")
1867        .flags(total | nozero | nonan)
1868        ;
1869    demandAccesses = demandHits + demandMisses;
1870    for (int i = 0; i < system->maxMasters(); i++) {
1871        demandAccesses.subname(i, system->getMasterName(i));
1872    }
1873
1874    overallAccesses
1875        .name(name() + ".overall_accesses")
1876        .desc("number of overall (read+write) accesses")
1877        .flags(total | nozero | nonan)
1878        ;
1879    overallAccesses = overallHits + overallMisses;
1880    for (int i = 0; i < system->maxMasters(); i++) {
1881        overallAccesses.subname(i, system->getMasterName(i));
1882    }
1883
1884    // miss rate formulas
1885    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1886        MemCmd cmd(access_idx);
1887        const string &cstr = cmd.toString();
1888
1889        missRate[access_idx]
1890            .name(name() + "." + cstr + "_miss_rate")
1891            .desc("miss rate for " + cstr + " accesses")
1892            .flags(total | nozero | nonan)
1893            ;
1894        missRate[access_idx] = misses[access_idx] / accesses[access_idx];
1895
1896        for (int i = 0; i < system->maxMasters(); i++) {
1897            missRate[access_idx].subname(i, system->getMasterName(i));
1898        }
1899    }
1900
1901    demandMissRate
1902        .name(name() + ".demand_miss_rate")
1903        .desc("miss rate for demand accesses")
1904        .flags(total | nozero | nonan)
1905        ;
1906    demandMissRate = demandMisses / demandAccesses;
1907    for (int i = 0; i < system->maxMasters(); i++) {
1908        demandMissRate.subname(i, system->getMasterName(i));
1909    }
1910
1911    overallMissRate
1912        .name(name() + ".overall_miss_rate")
1913        .desc("miss rate for overall accesses")
1914        .flags(total | nozero | nonan)
1915        ;
1916    overallMissRate = overallMisses / overallAccesses;
1917    for (int i = 0; i < system->maxMasters(); i++) {
1918        overallMissRate.subname(i, system->getMasterName(i));
1919    }
1920
1921    // miss latency formulas
1922    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
1923        MemCmd cmd(access_idx);
1924        const string &cstr = cmd.toString();
1925
1926        avgMissLatency[access_idx]
1927            .name(name() + "." + cstr + "_avg_miss_latency")
1928            .desc("average " + cstr + " miss latency")
1929            .flags(total | nozero | nonan)
1930            ;
1931        avgMissLatency[access_idx] =
1932            missLatency[access_idx] / misses[access_idx];
1933
1934        for (int i = 0; i < system->maxMasters(); i++) {
1935            avgMissLatency[access_idx].subname(i, system->getMasterName(i));
1936        }
1937    }
1938
1939    demandAvgMissLatency
1940        .name(name() + ".demand_avg_miss_latency")
1941        .desc("average overall miss latency")
1942        .flags(total | nozero | nonan)
1943        ;
1944    demandAvgMissLatency = demandMissLatency / demandMisses;
1945    for (int i = 0; i < system->maxMasters(); i++) {
1946        demandAvgMissLatency.subname(i, system->getMasterName(i));
1947    }
1948
1949    overallAvgMissLatency
1950        .name(name() + ".overall_avg_miss_latency")
1951        .desc("average overall miss latency")
1952        .flags(total | nozero | nonan)
1953        ;
1954    overallAvgMissLatency = overallMissLatency / overallMisses;
1955    for (int i = 0; i < system->maxMasters(); i++) {
1956        overallAvgMissLatency.subname(i, system->getMasterName(i));
1957    }
1958
1959    blocked_cycles.init(NUM_BLOCKED_CAUSES);
1960    blocked_cycles
1961        .name(name() + ".blocked_cycles")
1962        .desc("number of cycles access was blocked")
1963        .subname(Blocked_NoMSHRs, "no_mshrs")
1964        .subname(Blocked_NoTargets, "no_targets")
1965        ;
1966
1967
1968    blocked_causes.init(NUM_BLOCKED_CAUSES);
1969    blocked_causes
1970        .name(name() + ".blocked")
1971        .desc("number of cycles access was blocked")
1972        .subname(Blocked_NoMSHRs, "no_mshrs")
1973        .subname(Blocked_NoTargets, "no_targets")
1974        ;
1975
1976    avg_blocked
1977        .name(name() + ".avg_blocked_cycles")
1978        .desc("average number of cycles each access was blocked")
1979        .subname(Blocked_NoMSHRs, "no_mshrs")
1980        .subname(Blocked_NoTargets, "no_targets")
1981        ;
1982
1983    avg_blocked = blocked_cycles / blocked_causes;
1984
1985    unusedPrefetches
1986        .name(name() + ".unused_prefetches")
1987        .desc("number of HardPF blocks evicted w/o reference")
1988        .flags(nozero)
1989        ;
1990
1991    writebacks
1992        .init(system->maxMasters())
1993        .name(name() + ".writebacks")
1994        .desc("number of writebacks")
1995        .flags(total | nozero | nonan)
1996        ;
1997    for (int i = 0; i < system->maxMasters(); i++) {
1998        writebacks.subname(i, system->getMasterName(i));
1999    }
2000
2001    // MSHR statistics
2002    // MSHR hit statistics
2003    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2004        MemCmd cmd(access_idx);
2005        const string &cstr = cmd.toString();
2006
2007        mshr_hits[access_idx]
2008            .init(system->maxMasters())
2009            .name(name() + "." + cstr + "_mshr_hits")
2010            .desc("number of " + cstr + " MSHR hits")
2011            .flags(total | nozero | nonan)
2012            ;
2013        for (int i = 0; i < system->maxMasters(); i++) {
2014            mshr_hits[access_idx].subname(i, system->getMasterName(i));
2015        }
2016    }
2017
2018    demandMshrHits
2019        .name(name() + ".demand_mshr_hits")
2020        .desc("number of demand (read+write) MSHR hits")
2021        .flags(total | nozero | nonan)
2022        ;
2023    demandMshrHits = SUM_DEMAND(mshr_hits);
2024    for (int i = 0; i < system->maxMasters(); i++) {
2025        demandMshrHits.subname(i, system->getMasterName(i));
2026    }
2027
2028    overallMshrHits
2029        .name(name() + ".overall_mshr_hits")
2030        .desc("number of overall MSHR hits")
2031        .flags(total | nozero | nonan)
2032        ;
2033    overallMshrHits = demandMshrHits + SUM_NON_DEMAND(mshr_hits);
2034    for (int i = 0; i < system->maxMasters(); i++) {
2035        overallMshrHits.subname(i, system->getMasterName(i));
2036    }
2037
2038    // MSHR miss statistics
2039    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2040        MemCmd cmd(access_idx);
2041        const string &cstr = cmd.toString();
2042
2043        mshr_misses[access_idx]
2044            .init(system->maxMasters())
2045            .name(name() + "." + cstr + "_mshr_misses")
2046            .desc("number of " + cstr + " MSHR misses")
2047            .flags(total | nozero | nonan)
2048            ;
2049        for (int i = 0; i < system->maxMasters(); i++) {
2050            mshr_misses[access_idx].subname(i, system->getMasterName(i));
2051        }
2052    }
2053
2054    demandMshrMisses
2055        .name(name() + ".demand_mshr_misses")
2056        .desc("number of demand (read+write) MSHR misses")
2057        .flags(total | nozero | nonan)
2058        ;
2059    demandMshrMisses = SUM_DEMAND(mshr_misses);
2060    for (int i = 0; i < system->maxMasters(); i++) {
2061        demandMshrMisses.subname(i, system->getMasterName(i));
2062    }
2063
2064    overallMshrMisses
2065        .name(name() + ".overall_mshr_misses")
2066        .desc("number of overall MSHR misses")
2067        .flags(total | nozero | nonan)
2068        ;
2069    overallMshrMisses = demandMshrMisses + SUM_NON_DEMAND(mshr_misses);
2070    for (int i = 0; i < system->maxMasters(); i++) {
2071        overallMshrMisses.subname(i, system->getMasterName(i));
2072    }
2073
2074    // MSHR miss latency statistics
2075    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2076        MemCmd cmd(access_idx);
2077        const string &cstr = cmd.toString();
2078
2079        mshr_miss_latency[access_idx]
2080            .init(system->maxMasters())
2081            .name(name() + "." + cstr + "_mshr_miss_latency")
2082            .desc("number of " + cstr + " MSHR miss cycles")
2083            .flags(total | nozero | nonan)
2084            ;
2085        for (int i = 0; i < system->maxMasters(); i++) {
2086            mshr_miss_latency[access_idx].subname(i, system->getMasterName(i));
2087        }
2088    }
2089
2090    demandMshrMissLatency
2091        .name(name() + ".demand_mshr_miss_latency")
2092        .desc("number of demand (read+write) MSHR miss cycles")
2093        .flags(total | nozero | nonan)
2094        ;
2095    demandMshrMissLatency = SUM_DEMAND(mshr_miss_latency);
2096    for (int i = 0; i < system->maxMasters(); i++) {
2097        demandMshrMissLatency.subname(i, system->getMasterName(i));
2098    }
2099
2100    overallMshrMissLatency
2101        .name(name() + ".overall_mshr_miss_latency")
2102        .desc("number of overall MSHR miss cycles")
2103        .flags(total | nozero | nonan)
2104        ;
2105    overallMshrMissLatency =
2106        demandMshrMissLatency + SUM_NON_DEMAND(mshr_miss_latency);
2107    for (int i = 0; i < system->maxMasters(); i++) {
2108        overallMshrMissLatency.subname(i, system->getMasterName(i));
2109    }
2110
2111    // MSHR uncacheable statistics
2112    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2113        MemCmd cmd(access_idx);
2114        const string &cstr = cmd.toString();
2115
2116        mshr_uncacheable[access_idx]
2117            .init(system->maxMasters())
2118            .name(name() + "." + cstr + "_mshr_uncacheable")
2119            .desc("number of " + cstr + " MSHR uncacheable")
2120            .flags(total | nozero | nonan)
2121            ;
2122        for (int i = 0; i < system->maxMasters(); i++) {
2123            mshr_uncacheable[access_idx].subname(i, system->getMasterName(i));
2124        }
2125    }
2126
2127    overallMshrUncacheable
2128        .name(name() + ".overall_mshr_uncacheable_misses")
2129        .desc("number of overall MSHR uncacheable misses")
2130        .flags(total | nozero | nonan)
2131        ;
2132    overallMshrUncacheable =
2133        SUM_DEMAND(mshr_uncacheable) + SUM_NON_DEMAND(mshr_uncacheable);
2134    for (int i = 0; i < system->maxMasters(); i++) {
2135        overallMshrUncacheable.subname(i, system->getMasterName(i));
2136    }
2137
2138    // MSHR miss latency statistics
2139    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2140        MemCmd cmd(access_idx);
2141        const string &cstr = cmd.toString();
2142
2143        mshr_uncacheable_lat[access_idx]
2144            .init(system->maxMasters())
2145            .name(name() + "." + cstr + "_mshr_uncacheable_latency")
2146            .desc("number of " + cstr + " MSHR uncacheable cycles")
2147            .flags(total | nozero | nonan)
2148            ;
2149        for (int i = 0; i < system->maxMasters(); i++) {
2150            mshr_uncacheable_lat[access_idx].subname(
2151                i, system->getMasterName(i));
2152        }
2153    }
2154
2155    overallMshrUncacheableLatency
2156        .name(name() + ".overall_mshr_uncacheable_latency")
2157        .desc("number of overall MSHR uncacheable cycles")
2158        .flags(total | nozero | nonan)
2159        ;
2160    overallMshrUncacheableLatency =
2161        SUM_DEMAND(mshr_uncacheable_lat) +
2162        SUM_NON_DEMAND(mshr_uncacheable_lat);
2163    for (int i = 0; i < system->maxMasters(); i++) {
2164        overallMshrUncacheableLatency.subname(i, system->getMasterName(i));
2165    }
2166
2167#if 0
2168    // MSHR access formulas
2169    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2170        MemCmd cmd(access_idx);
2171        const string &cstr = cmd.toString();
2172
2173        mshrAccesses[access_idx]
2174            .name(name() + "." + cstr + "_mshr_accesses")
2175            .desc("number of " + cstr + " mshr accesses(hits+misses)")
2176            .flags(total | nozero | nonan)
2177            ;
2178        mshrAccesses[access_idx] =
2179            mshr_hits[access_idx] + mshr_misses[access_idx]
2180            + mshr_uncacheable[access_idx];
2181    }
2182
2183    demandMshrAccesses
2184        .name(name() + ".demand_mshr_accesses")
2185        .desc("number of demand (read+write) mshr accesses")
2186        .flags(total | nozero | nonan)
2187        ;
2188    demandMshrAccesses = demandMshrHits + demandMshrMisses;
2189
2190    overallMshrAccesses
2191        .name(name() + ".overall_mshr_accesses")
2192        .desc("number of overall (read+write) mshr accesses")
2193        .flags(total | nozero | nonan)
2194        ;
2195    overallMshrAccesses = overallMshrHits + overallMshrMisses
2196        + overallMshrUncacheable;
2197#endif
2198
2199    // MSHR miss rate formulas
2200    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2201        MemCmd cmd(access_idx);
2202        const string &cstr = cmd.toString();
2203
2204        mshrMissRate[access_idx]
2205            .name(name() + "." + cstr + "_mshr_miss_rate")
2206            .desc("mshr miss rate for " + cstr + " accesses")
2207            .flags(total | nozero | nonan)
2208            ;
2209        mshrMissRate[access_idx] =
2210            mshr_misses[access_idx] / accesses[access_idx];
2211
2212        for (int i = 0; i < system->maxMasters(); i++) {
2213            mshrMissRate[access_idx].subname(i, system->getMasterName(i));
2214        }
2215    }
2216
2217    demandMshrMissRate
2218        .name(name() + ".demand_mshr_miss_rate")
2219        .desc("mshr miss rate for demand accesses")
2220        .flags(total | nozero | nonan)
2221        ;
2222    demandMshrMissRate = demandMshrMisses / demandAccesses;
2223    for (int i = 0; i < system->maxMasters(); i++) {
2224        demandMshrMissRate.subname(i, system->getMasterName(i));
2225    }
2226
2227    overallMshrMissRate
2228        .name(name() + ".overall_mshr_miss_rate")
2229        .desc("mshr miss rate for overall accesses")
2230        .flags(total | nozero | nonan)
2231        ;
2232    overallMshrMissRate = overallMshrMisses / overallAccesses;
2233    for (int i = 0; i < system->maxMasters(); i++) {
2234        overallMshrMissRate.subname(i, system->getMasterName(i));
2235    }
2236
2237    // mshrMiss latency formulas
2238    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2239        MemCmd cmd(access_idx);
2240        const string &cstr = cmd.toString();
2241
2242        avgMshrMissLatency[access_idx]
2243            .name(name() + "." + cstr + "_avg_mshr_miss_latency")
2244            .desc("average " + cstr + " mshr miss latency")
2245            .flags(total | nozero | nonan)
2246            ;
2247        avgMshrMissLatency[access_idx] =
2248            mshr_miss_latency[access_idx] / mshr_misses[access_idx];
2249
2250        for (int i = 0; i < system->maxMasters(); i++) {
2251            avgMshrMissLatency[access_idx].subname(
2252                i, system->getMasterName(i));
2253        }
2254    }
2255
2256    demandAvgMshrMissLatency
2257        .name(name() + ".demand_avg_mshr_miss_latency")
2258        .desc("average overall mshr miss latency")
2259        .flags(total | nozero | nonan)
2260        ;
2261    demandAvgMshrMissLatency = demandMshrMissLatency / demandMshrMisses;
2262    for (int i = 0; i < system->maxMasters(); i++) {
2263        demandAvgMshrMissLatency.subname(i, system->getMasterName(i));
2264    }
2265
2266    overallAvgMshrMissLatency
2267        .name(name() + ".overall_avg_mshr_miss_latency")
2268        .desc("average overall mshr miss latency")
2269        .flags(total | nozero | nonan)
2270        ;
2271    overallAvgMshrMissLatency = overallMshrMissLatency / overallMshrMisses;
2272    for (int i = 0; i < system->maxMasters(); i++) {
2273        overallAvgMshrMissLatency.subname(i, system->getMasterName(i));
2274    }
2275
2276    // mshrUncacheable latency formulas
2277    for (int access_idx = 0; access_idx < MemCmd::NUM_MEM_CMDS; ++access_idx) {
2278        MemCmd cmd(access_idx);
2279        const string &cstr = cmd.toString();
2280
2281        avgMshrUncacheableLatency[access_idx]
2282            .name(name() + "." + cstr + "_avg_mshr_uncacheable_latency")
2283            .desc("average " + cstr + " mshr uncacheable latency")
2284            .flags(total | nozero | nonan)
2285            ;
2286        avgMshrUncacheableLatency[access_idx] =
2287            mshr_uncacheable_lat[access_idx] / mshr_uncacheable[access_idx];
2288
2289        for (int i = 0; i < system->maxMasters(); i++) {
2290            avgMshrUncacheableLatency[access_idx].subname(
2291                i, system->getMasterName(i));
2292        }
2293    }
2294
2295    overallAvgMshrUncacheableLatency
2296        .name(name() + ".overall_avg_mshr_uncacheable_latency")
2297        .desc("average overall mshr uncacheable latency")
2298        .flags(total | nozero | nonan)
2299        ;
2300    overallAvgMshrUncacheableLatency =
2301        overallMshrUncacheableLatency / overallMshrUncacheable;
2302    for (int i = 0; i < system->maxMasters(); i++) {
2303        overallAvgMshrUncacheableLatency.subname(i, system->getMasterName(i));
2304    }
2305
2306    replacements
2307        .name(name() + ".replacements")
2308        .desc("number of replacements")
2309        ;
2310}
2311
2312void
2313BaseCache::regProbePoints()
2314{
2315    ppHit = new ProbePointArg<PacketPtr>(this->getProbeManager(), "Hit");
2316    ppMiss = new ProbePointArg<PacketPtr>(this->getProbeManager(), "Miss");
2317    ppFill = new ProbePointArg<PacketPtr>(this->getProbeManager(), "Fill");
2318}
2319
2320///////////////
2321//
2322// CpuSidePort
2323//
2324///////////////
2325bool
2326BaseCache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt)
2327{
2328    // Snoops shouldn't happen when bypassing caches
2329    assert(!cache->system->bypassCaches());
2330
2331    assert(pkt->isResponse());
2332
2333    // Express snoop responses from master to slave, e.g., from L1 to L2
2334    cache->recvTimingSnoopResp(pkt);
2335    return true;
2336}
2337
2338
2339bool
2340BaseCache::CpuSidePort::tryTiming(PacketPtr pkt)
2341{
2342    if (cache->system->bypassCaches() || pkt->isExpressSnoop()) {
2343        // always let express snoop packets through even if blocked
2344        return true;
2345    } else if (blocked || mustSendRetry) {
2346        // either already committed to send a retry, or blocked
2347        mustSendRetry = true;
2348        return false;
2349    }
2350    mustSendRetry = false;
2351    return true;
2352}
2353
2354bool
2355BaseCache::CpuSidePort::recvTimingReq(PacketPtr pkt)
2356{
2357    assert(pkt->isRequest());
2358
2359    if (cache->system->bypassCaches()) {
2360        // Just forward the packet if caches are disabled.
2361        // @todo This should really enqueue the packet rather
2362        bool M5_VAR_USED success = cache->memSidePort.sendTimingReq(pkt);
2363        assert(success);
2364        return true;
2365    } else if (tryTiming(pkt)) {
2366        cache->recvTimingReq(pkt);
2367        return true;
2368    }
2369    return false;
2370}
2371
2372Tick
2373BaseCache::CpuSidePort::recvAtomic(PacketPtr pkt)
2374{
2375    if (cache->system->bypassCaches()) {
2376        // Forward the request if the system is in cache bypass mode.
2377        return cache->memSidePort.sendAtomic(pkt);
2378    } else {
2379        return cache->recvAtomic(pkt);
2380    }
2381}
2382
2383void
2384BaseCache::CpuSidePort::recvFunctional(PacketPtr pkt)
2385{
2386    if (cache->system->bypassCaches()) {
2387        // The cache should be flushed if we are in cache bypass mode,
2388        // so we don't need to check if we need to update anything.
2389        cache->memSidePort.sendFunctional(pkt);
2390        return;
2391    }
2392
2393    // functional request
2394    cache->functionalAccess(pkt, true);
2395}
2396
2397AddrRangeList
2398BaseCache::CpuSidePort::getAddrRanges() const
2399{
2400    return cache->getAddrRanges();
2401}
2402
2403
2404BaseCache::
2405CpuSidePort::CpuSidePort(const std::string &_name, BaseCache *_cache,
2406                         const std::string &_label)
2407    : CacheSlavePort(_name, _cache, _label), cache(_cache)
2408{
2409}
2410
2411///////////////
2412//
2413// MemSidePort
2414//
2415///////////////
2416bool
2417BaseCache::MemSidePort::recvTimingResp(PacketPtr pkt)
2418{
2419    cache->recvTimingResp(pkt);
2420    return true;
2421}
2422
2423// Express snooping requests to memside port
2424void
2425BaseCache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt)
2426{
2427    // Snoops shouldn't happen when bypassing caches
2428    assert(!cache->system->bypassCaches());
2429
2430    // handle snooping requests
2431    cache->recvTimingSnoopReq(pkt);
2432}
2433
2434Tick
2435BaseCache::MemSidePort::recvAtomicSnoop(PacketPtr pkt)
2436{
2437    // Snoops shouldn't happen when bypassing caches
2438    assert(!cache->system->bypassCaches());
2439
2440    return cache->recvAtomicSnoop(pkt);
2441}
2442
2443void
2444BaseCache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt)
2445{
2446    // Snoops shouldn't happen when bypassing caches
2447    assert(!cache->system->bypassCaches());
2448
2449    // functional snoop (note that in contrast to atomic we don't have
2450    // a specific functionalSnoop method, as they have the same
2451    // behaviour regardless)
2452    cache->functionalAccess(pkt, false);
2453}
2454
2455void
2456BaseCache::CacheReqPacketQueue::sendDeferredPacket()
2457{
2458    // sanity check
2459    assert(!waitingOnRetry);
2460
2461    // there should never be any deferred request packets in the
2462    // queue, instead we resly on the cache to provide the packets
2463    // from the MSHR queue or write queue
2464    assert(deferredPacketReadyTime() == MaxTick);
2465
2466    // check for request packets (requests & writebacks)
2467    QueueEntry* entry = cache.getNextQueueEntry();
2468
2469    if (!entry) {
2470        // can happen if e.g. we attempt a writeback and fail, but
2471        // before the retry, the writeback is eliminated because
2472        // we snoop another cache's ReadEx.
2473    } else {
2474        // let our snoop responses go first if there are responses to
2475        // the same addresses
2476        if (checkConflictingSnoop(entry->getTarget()->pkt)) {
2477            return;
2478        }
2479        waitingOnRetry = entry->sendPacket(cache);
2480    }
2481
2482    // if we succeeded and are not waiting for a retry, schedule the
2483    // next send considering when the next queue is ready, note that
2484    // snoop responses have their own packet queue and thus schedule
2485    // their own events
2486    if (!waitingOnRetry) {
2487        schedSendEvent(cache.nextQueueReadyTime());
2488    }
2489}
2490
2491BaseCache::MemSidePort::MemSidePort(const std::string &_name,
2492                                    BaseCache *_cache,
2493                                    const std::string &_label)
2494    : CacheMasterPort(_name, _cache, _reqQueue, _snoopRespQueue),
2495      _reqQueue(*_cache, *this, _snoopRespQueue, _label),
2496      _snoopRespQueue(*_cache, *this, true, _label), cache(_cache)
2497{
2498}
2499
2500void
2501WriteAllocator::updateMode(Addr write_addr, unsigned write_size,
2502                           Addr blk_addr)
2503{
2504    // check if we are continuing where the last write ended
2505    if (nextAddr == write_addr) {
2506        delayCtr[blk_addr] = delayThreshold;
2507        // stop if we have already saturated
2508        if (mode != WriteMode::NO_ALLOCATE) {
2509            byteCount += write_size;
2510            // switch to streaming mode if we have passed the lower
2511            // threshold
2512            if (mode == WriteMode::ALLOCATE &&
2513                byteCount > coalesceLimit) {
2514                mode = WriteMode::COALESCE;
2515                DPRINTF(Cache, "Switched to write coalescing\n");
2516            } else if (mode == WriteMode::COALESCE &&
2517                       byteCount > noAllocateLimit) {
2518                // and continue and switch to non-allocating mode if we
2519                // pass the upper threshold
2520                mode = WriteMode::NO_ALLOCATE;
2521                DPRINTF(Cache, "Switched to write-no-allocate\n");
2522            }
2523        }
2524    } else {
2525        // we did not see a write matching the previous one, start
2526        // over again
2527        byteCount = write_size;
2528        mode = WriteMode::ALLOCATE;
2529        resetDelay(blk_addr);
2530    }
2531    nextAddr = write_addr + write_size;
2532}
2533
2534WriteAllocator*
2535WriteAllocatorParams::create()
2536{
2537    return new WriteAllocator(this);
2538}
2539