1/*
2 * Copyright (c) 2010-2014 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) 2013 Amin Farmahini-Farahani
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: Andreas Hansson
41 * Ani Udipi
42 * Neha Agarwal
43 */
44
45#include "base/bitfield.hh"
46#include "base/trace.hh"
47#include "debug/DRAM.hh"
48#include "debug/DRAMState.hh"
49#include "debug/Drain.hh"
50#include "mem/dram_ctrl.hh"
51#include "sim/system.hh"
52
53using namespace std;
54
55DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) :
56 AbstractMemory(p),
57 port(name() + ".port", *this),
58 retryRdReq(false), retryWrReq(false),
59 busState(READ),
60 nextReqEvent(this), respondEvent(this), activateEvent(this),
61 prechargeEvent(this), refreshEvent(this), powerEvent(this),
62 drainManager(NULL),
63 deviceBusWidth(p->device_bus_width), burstLength(p->burst_length),
64 deviceRowBufferSize(p->device_rowbuffer_size),
65 devicesPerRank(p->devices_per_rank),
66 burstSize((devicesPerRank * burstLength * deviceBusWidth) / 8),
67 rowBufferSize(devicesPerRank * deviceRowBufferSize),
68 columnsPerRowBuffer(rowBufferSize / burstSize),
69 ranksPerChannel(p->ranks_per_channel),
70 banksPerRank(p->banks_per_rank), channels(p->channels), rowsPerBank(0),
71 readBufferSize(p->read_buffer_size),
72 writeBufferSize(p->write_buffer_size),
73 writeHighThreshold(writeBufferSize * p->write_high_thresh_perc / 100.0),
74 writeLowThreshold(writeBufferSize * p->write_low_thresh_perc / 100.0),
75 minWritesPerSwitch(p->min_writes_per_switch),
76 writesThisTime(0), readsThisTime(0),
77 tCK(p->tCK), tWTR(p->tWTR), tRTW(p->tRTW), tBURST(p->tBURST),
78 tRCD(p->tRCD), tCL(p->tCL), tRP(p->tRP), tRAS(p->tRAS), tWR(p->tWR),
79 tRTP(p->tRTP), tRFC(p->tRFC), tREFI(p->tREFI), tRRD(p->tRRD),
80 tXAW(p->tXAW), activationLimit(p->activation_limit),
81 memSchedPolicy(p->mem_sched_policy), addrMapping(p->addr_mapping),
82 pageMgmt(p->page_policy),
83 maxAccessesPerRow(p->max_accesses_per_row),
84 frontendLatency(p->static_frontend_latency),
85 backendLatency(p->static_backend_latency),
86 busBusyUntil(0), refreshDueAt(0), refreshState(REF_IDLE),
87 pwrStateTrans(PWR_IDLE), pwrState(PWR_IDLE), prevArrival(0),
88 nextReqTime(0), pwrStateTick(0), numBanksActive(0)
89{
90 // create the bank states based on the dimensions of the ranks and
91 // banks
92 banks.resize(ranksPerChannel);
93 actTicks.resize(ranksPerChannel);
94 for (size_t c = 0; c < ranksPerChannel; ++c) {
95 banks[c].resize(banksPerRank);
96 actTicks[c].resize(activationLimit, 0);
97 }
98
99 // set the bank indices
100 for (int r = 0; r < ranksPerChannel; r++) {
101 for (int b = 0; b < banksPerRank; b++) {
102 banks[r][b].rank = r;
103 banks[r][b].bank = b;
104 }
105 }
106
107 // perform a basic check of the write thresholds
108 if (p->write_low_thresh_perc >= p->write_high_thresh_perc)
109 fatal("Write buffer low threshold %d must be smaller than the "
110 "high threshold %d\n", p->write_low_thresh_perc,
111 p->write_high_thresh_perc);
112
113 // determine the rows per bank by looking at the total capacity
114 uint64_t capacity = ULL(1) << ceilLog2(AbstractMemory::size());
115
116 DPRINTF(DRAM, "Memory capacity %lld (%lld) bytes\n", capacity,
117 AbstractMemory::size());
118
119 DPRINTF(DRAM, "Row buffer size %d bytes with %d columns per row buffer\n",
120 rowBufferSize, columnsPerRowBuffer);
121
122 rowsPerBank = capacity / (rowBufferSize * banksPerRank * ranksPerChannel);
123
124 if (range.interleaved()) {
125 if (channels != range.stripes())
126 fatal("%s has %d interleaved address stripes but %d channel(s)\n",
127 name(), range.stripes(), channels);
128
129 if (addrMapping == Enums::RoRaBaChCo) {
130 if (rowBufferSize != range.granularity()) {
131 fatal("Interleaving of %s doesn't match RoRaBaChCo "
132 "address map\n", name());
133 }
134 } else if (addrMapping == Enums::RoRaBaCoCh) {
135 if (system()->cacheLineSize() != range.granularity()) {
136 fatal("Interleaving of %s doesn't match RoRaBaCoCh "
137 "address map\n", name());
138 }
139 } else if (addrMapping == Enums::RoCoRaBaCh) {
140 if (system()->cacheLineSize() != range.granularity())
141 fatal("Interleaving of %s doesn't match RoCoRaBaCh "
142 "address map\n", name());
143 }
144 }
145
146 // some basic sanity checks
147 if (tREFI <= tRP || tREFI <= tRFC) {
148 fatal("tREFI (%d) must be larger than tRP (%d) and tRFC (%d)\n",
149 tREFI, tRP, tRFC);
150 }
151}
152
153void
154DRAMCtrl::init()
155{
156 if (!port.isConnected()) {
157 fatal("DRAMCtrl %s is unconnected!\n", name());
158 } else {
159 port.sendRangeChange();
160 }
161}
162
163void
164DRAMCtrl::startup()
165{
166 // update the start tick for the precharge accounting to the
167 // current tick
168 pwrStateTick = curTick();
169
170 // shift the bus busy time sufficiently far ahead that we never
171 // have to worry about negative values when computing the time for
172 // the next request, this will add an insignificant bubble at the
173 // start of simulation
174 busBusyUntil = curTick() + tRP + tRCD + tCL;
175
176 // kick off the refresh, and give ourselves enough time to
177 // precharge
178 schedule(refreshEvent, curTick() + tREFI - tRP);
179}
180
181Tick
182DRAMCtrl::recvAtomic(PacketPtr pkt)
183{
184 DPRINTF(DRAM, "recvAtomic: %s 0x%x\n", pkt->cmdString(), pkt->getAddr());
185
186 // do the actual memory access and turn the packet into a response
187 access(pkt);
188
189 Tick latency = 0;
190 if (!pkt->memInhibitAsserted() && pkt->hasData()) {
191 // this value is not supposed to be accurate, just enough to
192 // keep things going, mimic a closed page
193 latency = tRP + tRCD + tCL;
194 }
195 return latency;
196}
197
198bool
199DRAMCtrl::readQueueFull(unsigned int neededEntries) const
200{
201 DPRINTF(DRAM, "Read queue limit %d, current size %d, entries needed %d\n",
202 readBufferSize, readQueue.size() + respQueue.size(),
203 neededEntries);
204
205 return
206 (readQueue.size() + respQueue.size() + neededEntries) > readBufferSize;
207}
208
209bool
210DRAMCtrl::writeQueueFull(unsigned int neededEntries) const
211{
212 DPRINTF(DRAM, "Write queue limit %d, current size %d, entries needed %d\n",
213 writeBufferSize, writeQueue.size(), neededEntries);
214 return (writeQueue.size() + neededEntries) > writeBufferSize;
215}
216
217DRAMCtrl::DRAMPacket*
218DRAMCtrl::decodeAddr(PacketPtr pkt, Addr dramPktAddr, unsigned size,
219 bool isRead)
220{
221 // decode the address based on the address mapping scheme, with
222 // Ro, Ra, Co, Ba and Ch denoting row, rank, column, bank and
223 // channel, respectively
224 uint8_t rank;
225 uint8_t bank;
226 // use a 64-bit unsigned during the computations as the row is
227 // always the top bits, and check before creating the DRAMPacket
228 uint64_t row;
229
230 // truncate the address to the access granularity
231 Addr addr = dramPktAddr / burstSize;
232
233 // we have removed the lowest order address bits that denote the
234 // position within the column
235 if (addrMapping == Enums::RoRaBaChCo) {
236 // the lowest order bits denote the column to ensure that
237 // sequential cache lines occupy the same row
238 addr = addr / columnsPerRowBuffer;
239
240 // take out the channel part of the address
241 addr = addr / channels;
242
243 // after the channel bits, get the bank bits to interleave
244 // over the banks
245 bank = addr % banksPerRank;
246 addr = addr / banksPerRank;
247
248 // after the bank, we get the rank bits which thus interleaves
249 // over the ranks
250 rank = addr % ranksPerChannel;
251 addr = addr / ranksPerChannel;
252
253 // lastly, get the row bits
254 row = addr % rowsPerBank;
255 addr = addr / rowsPerBank;
256 } else if (addrMapping == Enums::RoRaBaCoCh) {
257 // take out the channel part of the address
258 addr = addr / channels;
259
260 // next, the column
261 addr = addr / columnsPerRowBuffer;
262
263 // after the column bits, we get the bank bits to interleave
264 // over the banks
265 bank = addr % banksPerRank;
266 addr = addr / banksPerRank;
267
268 // after the bank, we get the rank bits which thus interleaves
269 // over the ranks
270 rank = addr % ranksPerChannel;
271 addr = addr / ranksPerChannel;
272
273 // lastly, get the row bits
274 row = addr % rowsPerBank;
275 addr = addr / rowsPerBank;
276 } else if (addrMapping == Enums::RoCoRaBaCh) {
277 // optimise for closed page mode and utilise maximum
278 // parallelism of the DRAM (at the cost of power)
279
280 // take out the channel part of the address, not that this has
281 // to match with how accesses are interleaved between the
282 // controllers in the address mapping
283 addr = addr / channels;
284
285 // start with the bank bits, as this provides the maximum
286 // opportunity for parallelism between requests
287 bank = addr % banksPerRank;
288 addr = addr / banksPerRank;
289
290 // next get the rank bits
291 rank = addr % ranksPerChannel;
292 addr = addr / ranksPerChannel;
293
294 // next the column bits which we do not need to keep track of
295 // and simply skip past
296 addr = addr / columnsPerRowBuffer;
297
298 // lastly, get the row bits
299 row = addr % rowsPerBank;
300 addr = addr / rowsPerBank;
301 } else
302 panic("Unknown address mapping policy chosen!");
303
304 assert(rank < ranksPerChannel);
305 assert(bank < banksPerRank);
306 assert(row < rowsPerBank);
307 assert(row < Bank::NO_ROW);
308
309 DPRINTF(DRAM, "Address: %lld Rank %d Bank %d Row %d\n",
310 dramPktAddr, rank, bank, row);
311
312 // create the corresponding DRAM packet with the entry time and
313 // ready time set to the current tick, the latter will be updated
314 // later
315 uint16_t bank_id = banksPerRank * rank + bank;
316 return new DRAMPacket(pkt, isRead, rank, bank, row, bank_id, dramPktAddr,
317 size, banks[rank][bank]);
318}
319
320void
321DRAMCtrl::addToReadQueue(PacketPtr pkt, unsigned int pktCount)
322{
323 // only add to the read queue here. whenever the request is
324 // eventually done, set the readyTime, and call schedule()
325 assert(!pkt->isWrite());
326
327 assert(pktCount != 0);
328
329 // if the request size is larger than burst size, the pkt is split into
330 // multiple DRAM packets
331 // Note if the pkt starting address is not aligened to burst size, the
332 // address of first DRAM packet is kept unaliged. Subsequent DRAM packets
333 // are aligned to burst size boundaries. This is to ensure we accurately
334 // check read packets against packets in write queue.
335 Addr addr = pkt->getAddr();
336 unsigned pktsServicedByWrQ = 0;
337 BurstHelper* burst_helper = NULL;
338 for (int cnt = 0; cnt < pktCount; ++cnt) {
339 unsigned size = std::min((addr | (burstSize - 1)) + 1,
340 pkt->getAddr() + pkt->getSize()) - addr;
341 readPktSize[ceilLog2(size)]++;
342 readBursts++;
343
344 // First check write buffer to see if the data is already at
345 // the controller
346 bool foundInWrQ = false;
347 for (auto i = writeQueue.begin(); i != writeQueue.end(); ++i) {
348 // check if the read is subsumed in the write entry we are
349 // looking at
350 if ((*i)->addr <= addr &&
351 (addr + size) <= ((*i)->addr + (*i)->size)) {
352 foundInWrQ = true;
353 servicedByWrQ++;
354 pktsServicedByWrQ++;
355 DPRINTF(DRAM, "Read to addr %lld with size %d serviced by "
356 "write queue\n", addr, size);
357 bytesReadWrQ += burstSize;
358 break;
359 }
360 }
361
362 // If not found in the write q, make a DRAM packet and
363 // push it onto the read queue
364 if (!foundInWrQ) {
365
366 // Make the burst helper for split packets
367 if (pktCount > 1 && burst_helper == NULL) {
368 DPRINTF(DRAM, "Read to addr %lld translates to %d "
369 "dram requests\n", pkt->getAddr(), pktCount);
370 burst_helper = new BurstHelper(pktCount);
371 }
372
373 DRAMPacket* dram_pkt = decodeAddr(pkt, addr, size, true);
374 dram_pkt->burstHelper = burst_helper;
375
376 assert(!readQueueFull(1));
377 rdQLenPdf[readQueue.size() + respQueue.size()]++;
378
379 DPRINTF(DRAM, "Adding to read queue\n");
380
381 readQueue.push_back(dram_pkt);
382
383 // Update stats
384 avgRdQLen = readQueue.size() + respQueue.size();
385 }
386
387 // Starting address of next dram pkt (aligend to burstSize boundary)
388 addr = (addr | (burstSize - 1)) + 1;
389 }
390
391 // If all packets are serviced by write queue, we send the repsonse back
392 if (pktsServicedByWrQ == pktCount) {
393 accessAndRespond(pkt, frontendLatency);
394 return;
395 }
396
397 // Update how many split packets are serviced by write queue
398 if (burst_helper != NULL)
399 burst_helper->burstsServiced = pktsServicedByWrQ;
400
401 // If we are not already scheduled to get a request out of the
402 // queue, do so now
403 if (!nextReqEvent.scheduled()) {
404 DPRINTF(DRAM, "Request scheduled immediately\n");
405 schedule(nextReqEvent, curTick());
406 }
407}
408
409void
410DRAMCtrl::addToWriteQueue(PacketPtr pkt, unsigned int pktCount)
411{
412 // only add to the write queue here. whenever the request is
413 // eventually done, set the readyTime, and call schedule()
414 assert(pkt->isWrite());
415
416 // if the request size is larger than burst size, the pkt is split into
417 // multiple DRAM packets
418 Addr addr = pkt->getAddr();
419 for (int cnt = 0; cnt < pktCount; ++cnt) {
420 unsigned size = std::min((addr | (burstSize - 1)) + 1,
421 pkt->getAddr() + pkt->getSize()) - addr;
422 writePktSize[ceilLog2(size)]++;
423 writeBursts++;
424
425 // see if we can merge with an existing item in the write
426 // queue and keep track of whether we have merged or not so we
427 // can stop at that point and also avoid enqueueing a new
428 // request
429 bool merged = false;
430 auto w = writeQueue.begin();
431
432 while(!merged && w != writeQueue.end()) {
433 // either of the two could be first, if they are the same
434 // it does not matter which way we go
435 if ((*w)->addr >= addr) {
436 // the existing one starts after the new one, figure
437 // out where the new one ends with respect to the
438 // existing one
439 if ((addr + size) >= ((*w)->addr + (*w)->size)) {
440 // check if the existing one is completely
441 // subsumed in the new one
442 DPRINTF(DRAM, "Merging write covering existing burst\n");
443 merged = true;
444 // update both the address and the size
445 (*w)->addr = addr;
446 (*w)->size = size;
447 } else if ((addr + size) >= (*w)->addr &&
448 ((*w)->addr + (*w)->size - addr) <= burstSize) {
449 // the new one is just before or partially
450 // overlapping with the existing one, and together
451 // they fit within a burst
452 DPRINTF(DRAM, "Merging write before existing burst\n");
453 merged = true;
454 // the existing queue item needs to be adjusted with
455 // respect to both address and size
456 (*w)->size = (*w)->addr + (*w)->size - addr;
457 (*w)->addr = addr;
458 }
459 } else {
460 // the new one starts after the current one, figure
461 // out where the existing one ends with respect to the
462 // new one
463 if (((*w)->addr + (*w)->size) >= (addr + size)) {
464 // check if the new one is completely subsumed in the
465 // existing one
466 DPRINTF(DRAM, "Merging write into existing burst\n");
467 merged = true;
468 // no adjustments necessary
469 } else if (((*w)->addr + (*w)->size) >= addr &&
470 (addr + size - (*w)->addr) <= burstSize) {
471 // the existing one is just before or partially
472 // overlapping with the new one, and together
473 // they fit within a burst
474 DPRINTF(DRAM, "Merging write after existing burst\n");
475 merged = true;
476 // the address is right, and only the size has
477 // to be adjusted
478 (*w)->size = addr + size - (*w)->addr;
479 }
480 }
481 ++w;
482 }
483
484 // if the item was not merged we need to create a new write
485 // and enqueue it
486 if (!merged) {
487 DRAMPacket* dram_pkt = decodeAddr(pkt, addr, size, false);
488
489 assert(writeQueue.size() < writeBufferSize);
490 wrQLenPdf[writeQueue.size()]++;
491
492 DPRINTF(DRAM, "Adding to write queue\n");
493
494 writeQueue.push_back(dram_pkt);
495
496 // Update stats
497 avgWrQLen = writeQueue.size();
498 } else {
499 // keep track of the fact that this burst effectively
500 // disappeared as it was merged with an existing one
501 mergedWrBursts++;
502 }
503
504 // Starting address of next dram pkt (aligend to burstSize boundary)
505 addr = (addr | (burstSize - 1)) + 1;
506 }
507
508 // we do not wait for the writes to be send to the actual memory,
509 // but instead take responsibility for the consistency here and
510 // snoop the write queue for any upcoming reads
511 // @todo, if a pkt size is larger than burst size, we might need a
512 // different front end latency
513 accessAndRespond(pkt, frontendLatency);
514
515 // If we are not already scheduled to get a request out of the
516 // queue, do so now
517 if (!nextReqEvent.scheduled()) {
518 DPRINTF(DRAM, "Request scheduled immediately\n");
519 schedule(nextReqEvent, curTick());
520 }
521}
522
523void
524DRAMCtrl::printQs() const {
525 DPRINTF(DRAM, "===READ QUEUE===\n\n");
526 for (auto i = readQueue.begin() ; i != readQueue.end() ; ++i) {
527 DPRINTF(DRAM, "Read %lu\n", (*i)->addr);
528 }
529 DPRINTF(DRAM, "\n===RESP QUEUE===\n\n");
530 for (auto i = respQueue.begin() ; i != respQueue.end() ; ++i) {
531 DPRINTF(DRAM, "Response %lu\n", (*i)->addr);
532 }
533 DPRINTF(DRAM, "\n===WRITE QUEUE===\n\n");
534 for (auto i = writeQueue.begin() ; i != writeQueue.end() ; ++i) {
535 DPRINTF(DRAM, "Write %lu\n", (*i)->addr);
536 }
537}
538
539bool
540DRAMCtrl::recvTimingReq(PacketPtr pkt)
541{
542 /// @todo temporary hack to deal with memory corruption issues until
543 /// 4-phase transactions are complete
544 for (int x = 0; x < pendingDelete.size(); x++)
545 delete pendingDelete[x];
546 pendingDelete.clear();
547
548 // This is where we enter from the outside world
549 DPRINTF(DRAM, "recvTimingReq: request %s addr %lld size %d\n",
550 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
551
552 // simply drop inhibited packets for now
553 if (pkt->memInhibitAsserted()) {
554 DPRINTF(DRAM, "Inhibited packet -- Dropping it now\n");
555 pendingDelete.push_back(pkt);
556 return true;
557 }
558
559 // Calc avg gap between requests
560 if (prevArrival != 0) {
561 totGap += curTick() - prevArrival;
562 }
563 prevArrival = curTick();
564
565
566 // Find out how many dram packets a pkt translates to
567 // If the burst size is equal or larger than the pkt size, then a pkt
568 // translates to only one dram packet. Otherwise, a pkt translates to
569 // multiple dram packets
570 unsigned size = pkt->getSize();
571 unsigned offset = pkt->getAddr() & (burstSize - 1);
572 unsigned int dram_pkt_count = divCeil(offset + size, burstSize);
573
574 // check local buffers and do not accept if full
575 if (pkt->isRead()) {
576 assert(size != 0);
577 if (readQueueFull(dram_pkt_count)) {
578 DPRINTF(DRAM, "Read queue full, not accepting\n");
579 // remember that we have to retry this port
580 retryRdReq = true;
581 numRdRetry++;
582 return false;
583 } else {
584 addToReadQueue(pkt, dram_pkt_count);
585 readReqs++;
586 bytesReadSys += size;
587 }
588 } else if (pkt->isWrite()) {
589 assert(size != 0);
590 if (writeQueueFull(dram_pkt_count)) {
591 DPRINTF(DRAM, "Write queue full, not accepting\n");
592 // remember that we have to retry this port
593 retryWrReq = true;
594 numWrRetry++;
595 return false;
596 } else {
597 addToWriteQueue(pkt, dram_pkt_count);
598 writeReqs++;
599 bytesWrittenSys += size;
600 }
601 } else {
602 DPRINTF(DRAM,"Neither read nor write, ignore timing\n");
603 neitherReadNorWrite++;
604 accessAndRespond(pkt, 1);
605 }
606
607 return true;
608}
609
610void
611DRAMCtrl::processRespondEvent()
612{
613 DPRINTF(DRAM,
614 "processRespondEvent(): Some req has reached its readyTime\n");
615
616 DRAMPacket* dram_pkt = respQueue.front();
617
618 if (dram_pkt->burstHelper) {
619 // it is a split packet
620 dram_pkt->burstHelper->burstsServiced++;
621 if (dram_pkt->burstHelper->burstsServiced ==
622 dram_pkt->burstHelper->burstCount) {
623 // we have now serviced all children packets of a system packet
624 // so we can now respond to the requester
625 // @todo we probably want to have a different front end and back
626 // end latency for split packets
627 accessAndRespond(dram_pkt->pkt, frontendLatency + backendLatency);
628 delete dram_pkt->burstHelper;
629 dram_pkt->burstHelper = NULL;
630 }
631 } else {
632 // it is not a split packet
633 accessAndRespond(dram_pkt->pkt, frontendLatency + backendLatency);
634 }
635
636 delete respQueue.front();
637 respQueue.pop_front();
638
639 if (!respQueue.empty()) {
640 assert(respQueue.front()->readyTime >= curTick());
641 assert(!respondEvent.scheduled());
642 schedule(respondEvent, respQueue.front()->readyTime);
643 } else {
644 // if there is nothing left in any queue, signal a drain
645 if (writeQueue.empty() && readQueue.empty() &&
646 drainManager) {
647 drainManager->signalDrainDone();
648 drainManager = NULL;
649 }
650 }
651
652 // We have made a location in the queue available at this point,
653 // so if there is a read that was forced to wait, retry now
654 if (retryRdReq) {
655 retryRdReq = false;
656 port.sendRetry();
657 }
658}
659
660void
661DRAMCtrl::chooseNext(std::deque<DRAMPacket*>& queue)
662{
663 // This method does the arbitration between requests. The chosen
664 // packet is simply moved to the head of the queue. The other
665 // methods know that this is the place to look. For example, with
666 // FCFS, this method does nothing
667 assert(!queue.empty());
668
669 if (queue.size() == 1) {
670 DPRINTF(DRAM, "Single request, nothing to do\n");
671 return;
672 }
673
674 if (memSchedPolicy == Enums::fcfs) {
675 // Do nothing, since the correct request is already head
676 } else if (memSchedPolicy == Enums::frfcfs) {
677 reorderQueue(queue);
678 } else
679 panic("No scheduling policy chosen\n");
680}
681
682void
683DRAMCtrl::reorderQueue(std::deque<DRAMPacket*>& queue)
684{
685 // Only determine this when needed
686 uint64_t earliest_banks = 0;
687
688 // Search for row hits first, if no row hit is found then schedule the
689 // packet to one of the earliest banks available
690 bool found_earliest_pkt = false;
691 auto selected_pkt_it = queue.begin();
692
693 for (auto i = queue.begin(); i != queue.end() ; ++i) {
694 DRAMPacket* dram_pkt = *i;
695 const Bank& bank = dram_pkt->bankRef;
696 // Check if it is a row hit
697 if (bank.openRow == dram_pkt->row) {
698 // FCFS within the hits
699 DPRINTF(DRAM, "Row buffer hit\n");
700 selected_pkt_it = i;
701 break;
702 } else if (!found_earliest_pkt) {
703 // No row hit, go for first ready
704 if (earliest_banks == 0)
705 earliest_banks = minBankActAt(queue);
706
707 // simplistic approximation of when the bank can issue an
708 // activate, this is calculated in minBankActAt and could
709 // be cached
710 Tick act_at = bank.openRow == Bank::NO_ROW ?
711 bank.actAllowedAt :
712 std::max(bank.preAllowedAt, curTick()) + tRP;
713
714 // Bank is ready or is the first available bank
715 if (act_at <= curTick() ||
716 bits(earliest_banks, dram_pkt->bankId, dram_pkt->bankId)) {
717 // Remember the packet to be scheduled to one of the earliest
718 // banks available, FCFS amongst the earliest banks
719 selected_pkt_it = i;
720 found_earliest_pkt = true;
721 }
722 }
723 }
724
725 DRAMPacket* selected_pkt = *selected_pkt_it;
726 queue.erase(selected_pkt_it);
727 queue.push_front(selected_pkt);
728}
729
730void
731DRAMCtrl::accessAndRespond(PacketPtr pkt, Tick static_latency)
732{
733 DPRINTF(DRAM, "Responding to Address %lld.. ",pkt->getAddr());
734
735 bool needsResponse = pkt->needsResponse();
736 // do the actual memory access which also turns the packet into a
737 // response
738 access(pkt);
739
740 // turn packet around to go back to requester if response expected
741 if (needsResponse) {
742 // access already turned the packet into a response
743 assert(pkt->isResponse());
744
745 // @todo someone should pay for this
746 pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
747
748 // queue the packet in the response queue to be sent out after
749 // the static latency has passed
750 port.schedTimingResp(pkt, curTick() + static_latency);
751 } else {
752 // @todo the packet is going to be deleted, and the DRAMPacket
753 // is still having a pointer to it
754 pendingDelete.push_back(pkt);
755 }
756
757 DPRINTF(DRAM, "Done\n");
758
759 return;
760}
761
762void
763DRAMCtrl::activateBank(Bank& bank, Tick act_tick, uint32_t row)
764{
765 // get the rank index from the bank
766 uint8_t rank = bank.rank;
767
768 assert(actTicks[rank].size() == activationLimit);
769
770 DPRINTF(DRAM, "Activate at tick %d\n", act_tick);
771
772 // update the open row
773 assert(bank.openRow == Bank::NO_ROW);
774 bank.openRow = row;
775
776 // start counting anew, this covers both the case when we
777 // auto-precharged, and when this access is forced to
778 // precharge
779 bank.bytesAccessed = 0;
780 bank.rowAccesses = 0;
781
782 ++numBanksActive;
783 assert(numBanksActive <= banksPerRank * ranksPerChannel);
784
785 DPRINTF(DRAM, "Activate bank at tick %lld, now got %d active\n",
786 act_tick, numBanksActive);
787
788 // The next access has to respect tRAS for this bank
789 bank.preAllowedAt = act_tick + tRAS;
790
791 // Respect the row-to-column command delay
792 bank.colAllowedAt = act_tick + tRCD;
793
794 // start by enforcing tRRD
795 for(int i = 0; i < banksPerRank; i++) {
796 // next activate to any bank in this rank must not happen
797 // before tRRD
798 banks[rank][i].actAllowedAt = std::max(act_tick + tRRD,
799 banks[rank][i].actAllowedAt);
800 }
801
802 // next, we deal with tXAW, if the activation limit is disabled
803 // then we are done
804 if (actTicks[rank].empty())
805 return;
806
807 // sanity check
808 if (actTicks[rank].back() && (act_tick - actTicks[rank].back()) < tXAW) {
809 panic("Got %d activates in window %d (%llu - %llu) which is smaller "
810 "than %llu\n", activationLimit, act_tick - actTicks[rank].back(),
811 act_tick, actTicks[rank].back(), tXAW);
812 }
813
814 // shift the times used for the book keeping, the last element
815 // (highest index) is the oldest one and hence the lowest value
816 actTicks[rank].pop_back();
817
818 // record an new activation (in the future)
819 actTicks[rank].push_front(act_tick);
820
821 // cannot activate more than X times in time window tXAW, push the
822 // next one (the X + 1'st activate) to be tXAW away from the
823 // oldest in our window of X
824 if (actTicks[rank].back() && (act_tick - actTicks[rank].back()) < tXAW) {
825 DPRINTF(DRAM, "Enforcing tXAW with X = %d, next activate no earlier "
826 "than %llu\n", activationLimit, actTicks[rank].back() + tXAW);
827 for(int j = 0; j < banksPerRank; j++)
828 // next activate must not happen before end of window
829 banks[rank][j].actAllowedAt =
830 std::max(actTicks[rank].back() + tXAW,
831 banks[rank][j].actAllowedAt);
832 }
833
834 // at the point when this activate takes place, make sure we
835 // transition to the active power state
836 if (!activateEvent.scheduled())
837 schedule(activateEvent, act_tick);
838 else if (activateEvent.when() > act_tick)
839 // move it sooner in time
840 reschedule(activateEvent, act_tick);
841}
842
843void
844DRAMCtrl::processActivateEvent()
845{
846 // we should transition to the active state as soon as any bank is active
847 if (pwrState != PWR_ACT)
848 // note that at this point numBanksActive could be back at
849 // zero again due to a precharge scheduled in the future
850 schedulePowerEvent(PWR_ACT, curTick());
851}
852
853void
854DRAMCtrl::prechargeBank(Bank& bank, Tick pre_at)
855{
856 // make sure the bank has an open row
857 assert(bank.openRow != Bank::NO_ROW);
858
859 // sample the bytes per activate here since we are closing
860 // the page
861 bytesPerActivate.sample(bank.bytesAccessed);
862
863 bank.openRow = Bank::NO_ROW;
864
865 // no precharge allowed before this one
866 bank.preAllowedAt = pre_at;
867
868 Tick pre_done_at = pre_at + tRP;
869
870 bank.actAllowedAt = std::max(bank.actAllowedAt, pre_done_at);
871
872 assert(numBanksActive != 0);
873 --numBanksActive;
874
875 DPRINTF(DRAM, "Precharging bank at tick %lld, now got %d active\n",
876 pre_at, numBanksActive);
877
878 // if we look at the current number of active banks we might be
879 // tempted to think the DRAM is now idle, however this can be
880 // undone by an activate that is scheduled to happen before we
881 // would have reached the idle state, so schedule an event and
882 // rather check once we actually make it to the point in time when
883 // the (last) precharge takes place
884 if (!prechargeEvent.scheduled())
885 schedule(prechargeEvent, pre_done_at);
886 else if (prechargeEvent.when() < pre_done_at)
887 reschedule(prechargeEvent, pre_done_at);
888}
889
890void
891DRAMCtrl::processPrechargeEvent()
892{
893 // if we reached zero, then special conditions apply as we track
894 // if all banks are precharged for the power models
895 if (numBanksActive == 0) {
896 // we should transition to the idle state when the last bank
897 // is precharged
898 schedulePowerEvent(PWR_IDLE, curTick());
899 }
900}
901
902void
903DRAMCtrl::doDRAMAccess(DRAMPacket* dram_pkt)
904{
905 DPRINTF(DRAM, "Timing access to addr %lld, rank/bank/row %d %d %d\n",
906 dram_pkt->addr, dram_pkt->rank, dram_pkt->bank, dram_pkt->row);
907
908 // get the bank
909 Bank& bank = dram_pkt->bankRef;
910
911 // for the state we need to track if it is a row hit or not
912 bool row_hit = true;
913
914 // respect any constraints on the command (e.g. tRCD or tCCD)
915 Tick cmd_at = std::max(bank.colAllowedAt, curTick());
916
917 // Determine the access latency and update the bank state
918 if (bank.openRow == dram_pkt->row) {
919 // nothing to do
920 } else {
921 row_hit = false;
922
923 // If there is a page open, precharge it.
924 if (bank.openRow != Bank::NO_ROW) {
925 prechargeBank(bank, std::max(bank.preAllowedAt, curTick()));
926 }
927
928 // next we need to account for the delay in activating the
929 // page
930 Tick act_tick = std::max(bank.actAllowedAt, curTick());
931
932 // Record the activation and deal with all the global timing
933 // constraints caused be a new activation (tRRD and tXAW)
934 activateBank(bank, act_tick, dram_pkt->row);
935
936 // issue the command as early as possible
937 cmd_at = bank.colAllowedAt;
938 }
939
940 // we need to wait until the bus is available before we can issue
941 // the command
942 cmd_at = std::max(cmd_at, busBusyUntil - tCL);
943
944 // update the packet ready time
945 dram_pkt->readyTime = cmd_at + tCL + tBURST;
946
947 // only one burst can use the bus at any one point in time
948 assert(dram_pkt->readyTime - busBusyUntil >= tBURST);
949
950 // not strictly necessary, but update the time for the next
951 // read/write (add a max with tCCD here)
952 bank.colAllowedAt = cmd_at + tBURST;
953
954 // If this is a write, we also need to respect the write recovery
955 // time before a precharge, in the case of a read, respect the
956 // read to precharge constraint
957 bank.preAllowedAt = std::max(bank.preAllowedAt,
958 dram_pkt->isRead ? cmd_at + tRTP :
959 dram_pkt->readyTime + tWR);
960
961 // increment the bytes accessed and the accesses per row
962 bank.bytesAccessed += burstSize;
963 ++bank.rowAccesses;
964
965 // if we reached the max, then issue with an auto-precharge
966 bool auto_precharge = pageMgmt == Enums::close ||
967 bank.rowAccesses == maxAccessesPerRow;
968
969 // if we did not hit the limit, we might still want to
970 // auto-precharge
971 if (!auto_precharge &&
972 (pageMgmt == Enums::open_adaptive ||
973 pageMgmt == Enums::close_adaptive)) {
974 // a twist on the open and close page policies:
975 // 1) open_adaptive page policy does not blindly keep the
976 // page open, but close it if there are no row hits, and there
977 // are bank conflicts in the queue
978 // 2) close_adaptive page policy does not blindly close the
979 // page, but closes it only if there are no row hits in the queue.
980 // In this case, only force an auto precharge when there
981 // are no same page hits in the queue
982 bool got_more_hits = false;
983 bool got_bank_conflict = false;
984
985 // either look at the read queue or write queue
986 const deque<DRAMPacket*>& queue = dram_pkt->isRead ? readQueue :
987 writeQueue;
988 auto p = queue.begin();
989 // make sure we are not considering the packet that we are
990 // currently dealing with (which is the head of the queue)
991 ++p;
992
993 // keep on looking until we have found required condition or
994 // reached the end
995 while (!(got_more_hits &&
996 (got_bank_conflict || pageMgmt == Enums::close_adaptive)) &&
997 p != queue.end()) {
998 bool same_rank_bank = (dram_pkt->rank == (*p)->rank) &&
999 (dram_pkt->bank == (*p)->bank);
1000 bool same_row = dram_pkt->row == (*p)->row;
1001 got_more_hits |= same_rank_bank && same_row;
1002 got_bank_conflict |= same_rank_bank && !same_row;
1003 ++p;
1004 }
1005
1006 // auto pre-charge when either
1007 // 1) open_adaptive policy, we have not got any more hits, and
1008 // have a bank conflict
1009 // 2) close_adaptive policy and we have not got any more hits
1010 auto_precharge = !got_more_hits &&
1011 (got_bank_conflict || pageMgmt == Enums::close_adaptive);
1012 }
1013
1014 // if this access should use auto-precharge, then we are
1015 // closing the row
1016 if (auto_precharge) {
1017 prechargeBank(bank, std::max(curTick(), bank.preAllowedAt));
1018
1019 DPRINTF(DRAM, "Auto-precharged bank: %d\n", dram_pkt->bankId);
1020 }
1021
1022 // Update bus state
1023 busBusyUntil = dram_pkt->readyTime;
1024
1025 DPRINTF(DRAM, "Access to %lld, ready at %lld bus busy until %lld.\n",
1026 dram_pkt->addr, dram_pkt->readyTime, busBusyUntil);
1027
1028 // Update the minimum timing between the requests, this is a
1029 // conservative estimate of when we have to schedule the next
1030 // request to not introduce any unecessary bubbles. In most cases
1031 // we will wake up sooner than we have to.
1032 nextReqTime = busBusyUntil - (tRP + tRCD + tCL);
1033
1034 // Update the stats and schedule the next request
1035 if (dram_pkt->isRead) {
1036 ++readsThisTime;
1037 if (row_hit)
1038 readRowHits++;
1039 bytesReadDRAM += burstSize;
1040 perBankRdBursts[dram_pkt->bankId]++;
1041
1042 // Update latency stats
1043 totMemAccLat += dram_pkt->readyTime - dram_pkt->entryTime;
1044 totBusLat += tBURST;
1045 totQLat += cmd_at - dram_pkt->entryTime;
1046 } else {
1047 ++writesThisTime;
1048 if (row_hit)
1049 writeRowHits++;
1050 bytesWritten += burstSize;
1051 perBankWrBursts[dram_pkt->bankId]++;
1052 }
1053}
1054
1055void
1056DRAMCtrl::processNextReqEvent()
1057{
1058 if (busState == READ_TO_WRITE) {
1059 DPRINTF(DRAM, "Switching to writes after %d reads with %d reads "
1060 "waiting\n", readsThisTime, readQueue.size());
1061
1062 // sample and reset the read-related stats as we are now
1063 // transitioning to writes, and all reads are done
1064 rdPerTurnAround.sample(readsThisTime);
1065 readsThisTime = 0;
1066
1067 // now proceed to do the actual writes
1068 busState = WRITE;
1069 } else if (busState == WRITE_TO_READ) {
1070 DPRINTF(DRAM, "Switching to reads after %d writes with %d writes "
1071 "waiting\n", writesThisTime, writeQueue.size());
1072
1073 wrPerTurnAround.sample(writesThisTime);
1074 writesThisTime = 0;
1075
1076 busState = READ;
1077 }
1078
1079 if (refreshState != REF_IDLE) {
1080 // if a refresh waiting for this event loop to finish, then hand
1081 // over now, and do not schedule a new nextReqEvent
1082 if (refreshState == REF_DRAIN) {
1083 DPRINTF(DRAM, "Refresh drain done, now precharging\n");
1084
1085 refreshState = REF_PRE;
1086
1087 // hand control back to the refresh event loop
1088 schedule(refreshEvent, curTick());
1089 }
1090
1091 // let the refresh finish before issuing any further requests
1092 return;
1093 }
1094
1095 // when we get here it is either a read or a write
1096 if (busState == READ) {
1097
1098 // track if we should switch or not
1099 bool switch_to_writes = false;
1100
1101 if (readQueue.empty()) {
1102 // In the case there is no read request to go next,
1103 // trigger writes if we have passed the low threshold (or
1104 // if we are draining)
1105 if (!writeQueue.empty() &&
1106 (drainManager || writeQueue.size() > writeLowThreshold)) {
1107
1108 switch_to_writes = true;
1109 } else {
1110 // check if we are drained
1111 if (respQueue.empty () && drainManager) {
1112 drainManager->signalDrainDone();
1113 drainManager = NULL;
1114 }
1115
1116 // nothing to do, not even any point in scheduling an
1117 // event for the next request
1118 return;
1119 }
1120 } else {
1121 // Figure out which read request goes next, and move it to the
1122 // front of the read queue
1123 chooseNext(readQueue);
1124
1125 DRAMPacket* dram_pkt = readQueue.front();
1126
1127 doDRAMAccess(dram_pkt);
1128
1129 // At this point we're done dealing with the request
1130 readQueue.pop_front();
1131
1132 // sanity check
1133 assert(dram_pkt->size <= burstSize);
1134 assert(dram_pkt->readyTime >= curTick());
1135
1136 // Insert into response queue. It will be sent back to the
1137 // requestor at its readyTime
1138 if (respQueue.empty()) {
1139 assert(!respondEvent.scheduled());
1140 schedule(respondEvent, dram_pkt->readyTime);
1141 } else {
1142 assert(respQueue.back()->readyTime <= dram_pkt->readyTime);
1143 assert(respondEvent.scheduled());
1144 }
1145
1146 respQueue.push_back(dram_pkt);
1147
1148 // we have so many writes that we have to transition
1149 if (writeQueue.size() > writeHighThreshold) {
1150 switch_to_writes = true;
1151 }
1152 }
1153
1154 // switching to writes, either because the read queue is empty
1155 // and the writes have passed the low threshold (or we are
1156 // draining), or because the writes hit the hight threshold
1157 if (switch_to_writes) {
1158 // transition to writing
1159 busState = READ_TO_WRITE;
1160
1161 // add a bubble to the data bus, as defined by the
1162 // tRTW parameter
1163 busBusyUntil += tRTW;
1164
1165 // update the minimum timing between the requests,
1166 // this shifts us back in time far enough to do any
1167 // bank preparation
1168 nextReqTime = busBusyUntil - (tRP + tRCD + tCL);
1169 }
1170 } else {
1171 chooseNext(writeQueue);
1172 DRAMPacket* dram_pkt = writeQueue.front();
1173 // sanity check
1174 assert(dram_pkt->size <= burstSize);
1175 doDRAMAccess(dram_pkt);
1176
1177 writeQueue.pop_front();
1178 delete dram_pkt;
1179
1180 // If we emptied the write queue, or got sufficiently below the
1181 // threshold (using the minWritesPerSwitch as the hysteresis) and
1182 // are not draining, or we have reads waiting and have done enough
1183 // writes, then switch to reads.
1184 if (writeQueue.empty() ||
1185 (writeQueue.size() + minWritesPerSwitch < writeLowThreshold &&
1186 !drainManager) ||
1187 (!readQueue.empty() && writesThisTime >= minWritesPerSwitch)) {
1188 // turn the bus back around for reads again
1189 busState = WRITE_TO_READ;
1190
1191 // note that the we switch back to reads also in the idle
1192 // case, which eventually will check for any draining and
1193 // also pause any further scheduling if there is really
1194 // nothing to do
1195
1196 // here we get a bit creative and shift the bus busy time not
1197 // just the tWTR, but also a CAS latency to capture the fact
1198 // that we are allowed to prepare a new bank, but not issue a
1199 // read command until after tWTR, in essence we capture a
1200 // bubble on the data bus that is tWTR + tCL
1201 busBusyUntil += tWTR + tCL;
1202
1203 // update the minimum timing between the requests, this shifts
1204 // us back in time far enough to do any bank preparation
1205 nextReqTime = busBusyUntil - (tRP + tRCD + tCL);
1206 }
1207 }
1208
1209 schedule(nextReqEvent, std::max(nextReqTime, curTick()));
1210
1211 // If there is space available and we have writes waiting then let
1212 // them retry. This is done here to ensure that the retry does not
1213 // cause a nextReqEvent to be scheduled before we do so as part of
1214 // the next request processing
1215 if (retryWrReq && writeQueue.size() < writeBufferSize) {
1216 retryWrReq = false;
1217 port.sendRetry();
1218 }
1219}
1220
1221uint64_t
1222DRAMCtrl::minBankActAt(const deque<DRAMPacket*>& queue) const
1223{
1224 uint64_t bank_mask = 0;
1225 Tick min_act_at = MaxTick;
1226
1227 // deterimne if we have queued transactions targetting a
1228 // bank in question
1229 vector<bool> got_waiting(ranksPerChannel * banksPerRank, false);
1230 for (auto p = queue.begin(); p != queue.end(); ++p) {
1231 got_waiting[(*p)->bankId] = true;
1232 }
1233
1234 for (int i = 0; i < ranksPerChannel; i++) {
1235 for (int j = 0; j < banksPerRank; j++) {
1236 uint8_t bank_id = i * banksPerRank + j;
1237
1238 // if we have waiting requests for the bank, and it is
1239 // amongst the first available, update the mask
1240 if (got_waiting[bank_id]) {
1241 // simplistic approximation of when the bank can issue
1242 // an activate, ignoring any rank-to-rank switching
1243 // cost
1244 Tick act_at = banks[i][j].openRow == Bank::NO_ROW ?
1245 banks[i][j].actAllowedAt :
1246 std::max(banks[i][j].preAllowedAt, curTick()) + tRP;
1247
1248 if (act_at <= min_act_at) {
1249 // reset bank mask if new minimum is found
1250 if (act_at < min_act_at)
1251 bank_mask = 0;
1252 // set the bit corresponding to the available bank
1253 replaceBits(bank_mask, bank_id, bank_id, 1);
1254 min_act_at = act_at;
1255 }
1256 }
1257 }
1258 }
1259
1260 return bank_mask;
1261}
1262
1263void
1264DRAMCtrl::processRefreshEvent()
1265{
1266 // when first preparing the refresh, remember when it was due
1267 if (refreshState == REF_IDLE) {
1268 // remember when the refresh is due
1269 refreshDueAt = curTick();
1270
1271 // proceed to drain
1272 refreshState = REF_DRAIN;
1273
1274 DPRINTF(DRAM, "Refresh due\n");
1275 }
1276
1277 // let any scheduled read or write go ahead, after which it will
1278 // hand control back to this event loop
1279 if (refreshState == REF_DRAIN) {
1280 if (nextReqEvent.scheduled()) {
1281 // hand control over to the request loop until it is
1282 // evaluated next
1283 DPRINTF(DRAM, "Refresh awaiting draining\n");
1284
1285 return;
1286 } else {
1287 refreshState = REF_PRE;
1288 }
1289 }
1290
1291 // at this point, ensure that all banks are precharged
1292 if (refreshState == REF_PRE) {
1293 // precharge any active bank if we are not already in the idle
1294 // state
1295 if (pwrState != PWR_IDLE) {
1296 // at the moment, we use a precharge all even if there is
1297 // only a single bank open
1298 DPRINTF(DRAM, "Precharging all\n");
1299
1300 // first determine when we can precharge
1301 Tick pre_at = curTick();
1302 for (int i = 0; i < ranksPerChannel; i++) {
1303 for (int j = 0; j < banksPerRank; j++) {
1304 // respect both causality and any existing bank
1305 // constraints, some banks could already have a
1306 // (auto) precharge scheduled
1307 pre_at = std::max(banks[i][j].preAllowedAt, pre_at);
1308 }
1309 }
1310
1311 // make sure all banks are precharged, and for those that
1312 // already are, update their availability
1313 Tick act_allowed_at = pre_at + tRP;
1314
1315 for (int i = 0; i < ranksPerChannel; i++) {
1316 for (int j = 0; j < banksPerRank; j++) {
1317 if (banks[i][j].openRow != Bank::NO_ROW) {
1318 prechargeBank(banks[i][j], pre_at);
1319 } else {
1320 banks[i][j].actAllowedAt =
1321 std::max(banks[i][j].actAllowedAt, act_allowed_at);
1322 banks[i][j].preAllowedAt =
1323 std::max(banks[i][j].preAllowedAt, pre_at);
1324 }
1325 }
1326 }
1327 } else {
1328 DPRINTF(DRAM, "All banks already precharged, starting refresh\n");
1329
1330 // go ahead and kick the power state machine into gear if
1331 // we are already idle
1332 schedulePowerEvent(PWR_REF, curTick());
1333 }
1334
1335 refreshState = REF_RUN;
1336 assert(numBanksActive == 0);
1337
1338 // wait for all banks to be precharged, at which point the
1339 // power state machine will transition to the idle state, and
1340 // automatically move to a refresh, at that point it will also
1341 // call this method to get the refresh event loop going again
1342 return;
1343 }
1344
1345 // last but not least we perform the actual refresh
1346 if (refreshState == REF_RUN) {
1347 // should never get here with any banks active
1348 assert(numBanksActive == 0);
1349 assert(pwrState == PWR_REF);
1350
1351 Tick ref_done_at = curTick() + tRFC;
1352
1353 for (int i = 0; i < ranksPerChannel; i++) {
1354 for (int j = 0; j < banksPerRank; j++) {
1355 banks[i][j].actAllowedAt = ref_done_at;
1356 }
1357 }
1358
1359 // make sure we did not wait so long that we cannot make up
1360 // for it
1361 if (refreshDueAt + tREFI < ref_done_at) {
1362 fatal("Refresh was delayed so long we cannot catch up\n");
1363 }
1364
1365 // compensate for the delay in actually performing the refresh
1366 // when scheduling the next one
1367 schedule(refreshEvent, refreshDueAt + tREFI - tRP);
1368
1369 assert(!powerEvent.scheduled());
1370
1371 // move to the idle power state once the refresh is done, this
1372 // will also move the refresh state machine to the refresh
1373 // idle state
1374 schedulePowerEvent(PWR_IDLE, ref_done_at);
1375
1376 DPRINTF(DRAMState, "Refresh done at %llu and next refresh at %llu\n",
1377 ref_done_at, refreshDueAt + tREFI);
1378 }
1379}
1380
1381void
1382DRAMCtrl::schedulePowerEvent(PowerState pwr_state, Tick tick)
1383{
1384 // respect causality
1385 assert(tick >= curTick());
1386
1387 if (!powerEvent.scheduled()) {
1388 DPRINTF(DRAMState, "Scheduling power event at %llu to state %d\n",
1389 tick, pwr_state);
1390
1391 // insert the new transition
1392 pwrStateTrans = pwr_state;
1393
1394 schedule(powerEvent, tick);
1395 } else {
1396 panic("Scheduled power event at %llu to state %d, "
1397 "with scheduled event at %llu to %d\n", tick, pwr_state,
1398 powerEvent.when(), pwrStateTrans);
1399 }
1400}
1401
1402void
1403DRAMCtrl::processPowerEvent()
1404{
1405 // remember where we were, and for how long
1406 Tick duration = curTick() - pwrStateTick;
1407 PowerState prev_state = pwrState;
1408
1409 // update the accounting
1410 pwrStateTime[prev_state] += duration;
1411
1412 pwrState = pwrStateTrans;
1413 pwrStateTick = curTick();
1414
1415 if (pwrState == PWR_IDLE) {
1416 DPRINTF(DRAMState, "All banks precharged\n");
1417
1418 // if we were refreshing, make sure we start scheduling requests again
1419 if (prev_state == PWR_REF) {
1420 DPRINTF(DRAMState, "Was refreshing for %llu ticks\n", duration);
1421 assert(pwrState == PWR_IDLE);
1422
1423 // kick things into action again
1424 refreshState = REF_IDLE;
1425 assert(!nextReqEvent.scheduled());
1426 schedule(nextReqEvent, curTick());
1427 } else {
1428 assert(prev_state == PWR_ACT);
1429
1430 // if we have a pending refresh, and are now moving to
1431 // the idle state, direclty transition to a refresh
1432 if (refreshState == REF_RUN) {
1433 // there should be nothing waiting at this point
1434 assert(!powerEvent.scheduled());
1435
1436 // update the state in zero time and proceed below
1437 pwrState = PWR_REF;
1438 }
1439 }
1440 }
1441
1442 // we transition to the refresh state, let the refresh state
1443 // machine know of this state update and let it deal with the
1444 // scheduling of the next power state transition as well as the
1445 // following refresh
1446 if (pwrState == PWR_REF) {
1447 DPRINTF(DRAMState, "Refreshing\n");
1448 // kick the refresh event loop into action again, and that
1449 // in turn will schedule a transition to the idle power
1450 // state once the refresh is done
1451 assert(refreshState == REF_RUN);
1452 processRefreshEvent();
1453 }
1454}
1455
1456void
1457DRAMCtrl::regStats()
1458{
1459 using namespace Stats;
1460
1461 AbstractMemory::regStats();
1462
1463 readReqs
1464 .name(name() + ".readReqs")
1465 .desc("Number of read requests accepted");
1466
1467 writeReqs
1468 .name(name() + ".writeReqs")
1469 .desc("Number of write requests accepted");
1470
1471 readBursts
1472 .name(name() + ".readBursts")
1473 .desc("Number of DRAM read bursts, "
1474 "including those serviced by the write queue");
1475
1476 writeBursts
1477 .name(name() + ".writeBursts")
1478 .desc("Number of DRAM write bursts, "
1479 "including those merged in the write queue");
1480
1481 servicedByWrQ
1482 .name(name() + ".servicedByWrQ")
1483 .desc("Number of DRAM read bursts serviced by the write queue");
1484
1485 mergedWrBursts
1486 .name(name() + ".mergedWrBursts")
1487 .desc("Number of DRAM write bursts merged with an existing one");
1488
1489 neitherReadNorWrite
1490 .name(name() + ".neitherReadNorWriteReqs")
1491 .desc("Number of requests that are neither read nor write");
1492
1493 perBankRdBursts
1494 .init(banksPerRank * ranksPerChannel)
1495 .name(name() + ".perBankRdBursts")
1496 .desc("Per bank write bursts");
1497
1498 perBankWrBursts
1499 .init(banksPerRank * ranksPerChannel)
1500 .name(name() + ".perBankWrBursts")
1501 .desc("Per bank write bursts");
1502
1503 avgRdQLen
1504 .name(name() + ".avgRdQLen")
1505 .desc("Average read queue length when enqueuing")
1506 .precision(2);
1507
1508 avgWrQLen
1509 .name(name() + ".avgWrQLen")
1510 .desc("Average write queue length when enqueuing")
1511 .precision(2);
1512
1513 totQLat
1514 .name(name() + ".totQLat")
1515 .desc("Total ticks spent queuing");
1516
1517 totBusLat
1518 .name(name() + ".totBusLat")
1519 .desc("Total ticks spent in databus transfers");
1520
1521 totMemAccLat
1522 .name(name() + ".totMemAccLat")
1523 .desc("Total ticks spent from burst creation until serviced "
1524 "by the DRAM");
1525
1526 avgQLat
1527 .name(name() + ".avgQLat")
1528 .desc("Average queueing delay per DRAM burst")
1529 .precision(2);
1530
1531 avgQLat = totQLat / (readBursts - servicedByWrQ);
1532
1533 avgBusLat
1534 .name(name() + ".avgBusLat")
1535 .desc("Average bus latency per DRAM burst")
1536 .precision(2);
1537
1538 avgBusLat = totBusLat / (readBursts - servicedByWrQ);
1539
1540 avgMemAccLat
1541 .name(name() + ".avgMemAccLat")
1542 .desc("Average memory access latency per DRAM burst")
1543 .precision(2);
1544
1545 avgMemAccLat = totMemAccLat / (readBursts - servicedByWrQ);
1546
1547 numRdRetry
1548 .name(name() + ".numRdRetry")
1549 .desc("Number of times read queue was full causing retry");
1550
1551 numWrRetry
1552 .name(name() + ".numWrRetry")
1553 .desc("Number of times write queue was full causing retry");
1554
1555 readRowHits
1556 .name(name() + ".readRowHits")
1557 .desc("Number of row buffer hits during reads");
1558
1559 writeRowHits
1560 .name(name() + ".writeRowHits")
1561 .desc("Number of row buffer hits during writes");
1562
1563 readRowHitRate
1564 .name(name() + ".readRowHitRate")
1565 .desc("Row buffer hit rate for reads")
1566 .precision(2);
1567
1568 readRowHitRate = (readRowHits / (readBursts - servicedByWrQ)) * 100;
1569
1570 writeRowHitRate
1571 .name(name() + ".writeRowHitRate")
1572 .desc("Row buffer hit rate for writes")
1573 .precision(2);
1574
1575 writeRowHitRate = (writeRowHits / (writeBursts - mergedWrBursts)) * 100;
1576
1577 readPktSize
1578 .init(ceilLog2(burstSize) + 1)
1579 .name(name() + ".readPktSize")
1580 .desc("Read request sizes (log2)");
1581
1582 writePktSize
1583 .init(ceilLog2(burstSize) + 1)
1584 .name(name() + ".writePktSize")
1585 .desc("Write request sizes (log2)");
1586
1587 rdQLenPdf
1588 .init(readBufferSize)
1589 .name(name() + ".rdQLenPdf")
1590 .desc("What read queue length does an incoming req see");
1591
1592 wrQLenPdf
1593 .init(writeBufferSize)
1594 .name(name() + ".wrQLenPdf")
1595 .desc("What write queue length does an incoming req see");
1596
1597 bytesPerActivate
1598 .init(maxAccessesPerRow)
1599 .name(name() + ".bytesPerActivate")
1600 .desc("Bytes accessed per row activation")
1601 .flags(nozero);
1602
1603 rdPerTurnAround
1604 .init(readBufferSize)
1605 .name(name() + ".rdPerTurnAround")
1606 .desc("Reads before turning the bus around for writes")
1607 .flags(nozero);
1608
1609 wrPerTurnAround
1610 .init(writeBufferSize)
1611 .name(name() + ".wrPerTurnAround")
1612 .desc("Writes before turning the bus around for reads")
1613 .flags(nozero);
1614
1615 bytesReadDRAM
1616 .name(name() + ".bytesReadDRAM")
1617 .desc("Total number of bytes read from DRAM");
1618
1619 bytesReadWrQ
1620 .name(name() + ".bytesReadWrQ")
1621 .desc("Total number of bytes read from write queue");
1622
1623 bytesWritten
1624 .name(name() + ".bytesWritten")
1625 .desc("Total number of bytes written to DRAM");
1626
1627 bytesReadSys
1628 .name(name() + ".bytesReadSys")
1629 .desc("Total read bytes from the system interface side");
1630
1631 bytesWrittenSys
1632 .name(name() + ".bytesWrittenSys")
1633 .desc("Total written bytes from the system interface side");
1634
1635 avgRdBW
1636 .name(name() + ".avgRdBW")
1637 .desc("Average DRAM read bandwidth in MiByte/s")
1638 .precision(2);
1639
1640 avgRdBW = (bytesReadDRAM / 1000000) / simSeconds;
1641
1642 avgWrBW
1643 .name(name() + ".avgWrBW")
1644 .desc("Average achieved write bandwidth in MiByte/s")
1645 .precision(2);
1646
1647 avgWrBW = (bytesWritten / 1000000) / simSeconds;
1648
1649 avgRdBWSys
1650 .name(name() + ".avgRdBWSys")
1651 .desc("Average system read bandwidth in MiByte/s")
1652 .precision(2);
1653
1654 avgRdBWSys = (bytesReadSys / 1000000) / simSeconds;
1655
1656 avgWrBWSys
1657 .name(name() + ".avgWrBWSys")
1658 .desc("Average system write bandwidth in MiByte/s")
1659 .precision(2);
1660
1661 avgWrBWSys = (bytesWrittenSys / 1000000) / simSeconds;
1662
1663 peakBW
1664 .name(name() + ".peakBW")
1665 .desc("Theoretical peak bandwidth in MiByte/s")
1666 .precision(2);
1667
1668 peakBW = (SimClock::Frequency / tBURST) * burstSize / 1000000;
1669
1670 busUtil
1671 .name(name() + ".busUtil")
1672 .desc("Data bus utilization in percentage")
1673 .precision(2);
1674
1675 busUtil = (avgRdBW + avgWrBW) / peakBW * 100;
1676
1677 totGap
1678 .name(name() + ".totGap")
1679 .desc("Total gap between requests");
1680
1681 avgGap
1682 .name(name() + ".avgGap")
1683 .desc("Average gap between requests")
1684 .precision(2);
1685
1686 avgGap = totGap / (readReqs + writeReqs);
1687
1688 // Stats for DRAM Power calculation based on Micron datasheet
1689 busUtilRead
1690 .name(name() + ".busUtilRead")
1691 .desc("Data bus utilization in percentage for reads")
1692 .precision(2);
1693
1694 busUtilRead = avgRdBW / peakBW * 100;
1695
1696 busUtilWrite
1697 .name(name() + ".busUtilWrite")
1698 .desc("Data bus utilization in percentage for writes")
1699 .precision(2);
1700
1701 busUtilWrite = avgWrBW / peakBW * 100;
1702
1703 pageHitRate
1704 .name(name() + ".pageHitRate")
1705 .desc("Row buffer hit rate, read and write combined")
1706 .precision(2);
1707
1708 pageHitRate = (writeRowHits + readRowHits) /
1709 (writeBursts - mergedWrBursts + readBursts - servicedByWrQ) * 100;
1710
1711 pwrStateTime
1712 .init(5)
1713 .name(name() + ".memoryStateTime")
1714 .desc("Time in different power states");
1715 pwrStateTime.subname(0, "IDLE");
1716 pwrStateTime.subname(1, "REF");
1717 pwrStateTime.subname(2, "PRE_PDN");
1718 pwrStateTime.subname(3, "ACT");
1719 pwrStateTime.subname(4, "ACT_PDN");
1720}
1721
1722void
1723DRAMCtrl::recvFunctional(PacketPtr pkt)
1724{
1725 // rely on the abstract memory
1726 functionalAccess(pkt);
1727}
1728
1729BaseSlavePort&
1730DRAMCtrl::getSlavePort(const string &if_name, PortID idx)
1731{
1732 if (if_name != "port") {
1733 return MemObject::getSlavePort(if_name, idx);
1734 } else {
1735 return port;
1736 }
1737}
1738
1739unsigned int
1740DRAMCtrl::drain(DrainManager *dm)
1741{
1742 unsigned int count = port.drain(dm);
1743
1744 // if there is anything in any of our internal queues, keep track
1745 // of that as well
1746 if (!(writeQueue.empty() && readQueue.empty() &&
1747 respQueue.empty())) {
1748 DPRINTF(Drain, "DRAM controller not drained, write: %d, read: %d,"
1749 " resp: %d\n", writeQueue.size(), readQueue.size(),
1750 respQueue.size());
1751 ++count;
1752 drainManager = dm;
1753
1754 // the only part that is not drained automatically over time
1755 // is the write queue, thus kick things into action if needed
1756 if (!writeQueue.empty() && !nextReqEvent.scheduled()) {
1757 schedule(nextReqEvent, curTick());
1758 }
1759 }
1760
1761 if (count)
1762 setDrainState(Drainable::Draining);
1763 else
1764 setDrainState(Drainable::Drained);
1765 return count;
1766}
1767
1768DRAMCtrl::MemoryPort::MemoryPort(const std::string& name, DRAMCtrl& _memory)
1769 : QueuedSlavePort(name, &_memory, queue), queue(_memory, *this),
1770 memory(_memory)
1771{ }
1772
1773AddrRangeList
1774DRAMCtrl::MemoryPort::getAddrRanges() const
1775{
1776 AddrRangeList ranges;
1777 ranges.push_back(memory.getAddrRange());
1778 return ranges;
1779}
1780
1781void
1782DRAMCtrl::MemoryPort::recvFunctional(PacketPtr pkt)
1783{
1784 pkt->pushLabel(memory.name());
1785
1786 if (!queue.checkFunctional(pkt)) {
1787 // Default implementation of SimpleTimingPort::recvFunctional()
1788 // calls recvAtomic() and throws away the latency; we can save a
1789 // little here by just not calculating the latency.
1790 memory.recvFunctional(pkt);
1791 }
1792
1793 pkt->popLabel();
1794}
1795
1796Tick
1797DRAMCtrl::MemoryPort::recvAtomic(PacketPtr pkt)
1798{
1799 return memory.recvAtomic(pkt);
1800}
1801
1802bool
1803DRAMCtrl::MemoryPort::recvTimingReq(PacketPtr pkt)
1804{
1805 // pass it to the memory controller
1806 return memory.recvTimingReq(pkt);
1807}
1808
1809DRAMCtrl*
1810DRAMCtrlParams::create()
1811{
1812 return new DRAMCtrl(this);
1813}