2 * Copyright (c) 2010-2018 ARM Limited
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.
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010,2015 Advanced Micro Devices, Inc.
16 * All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 * Authors: Erik Hallnor
55 #include "mem/cache/cache.hh"
57 #include "base/logging.hh"
58 #include "base/types.hh"
59 #include "debug/Cache.hh"
60 #include "debug/CachePort.hh"
61 #include "debug/CacheTags.hh"
62 #include "debug/CacheVerbose.hh"
63 #include "mem/cache/blk.hh"
64 #include "mem/cache/mshr.hh"
65 #include "mem/cache/prefetch/base.hh"
66 #include "sim/sim_exit.hh"
68 Cache::Cache(const CacheParams
*p
)
69 : BaseCache(p
, p
->system
->cacheLineSize()),
71 prefetcher(p
->prefetcher
),
73 prefetchOnAccess(p
->prefetch_on_access
),
74 clusivity(p
->clusivity
),
75 writebackClean(p
->writeback_clean
),
76 tempBlockWriteback(nullptr),
77 writebackTempBlockAtomicEvent([this]{ writebackTempBlockAtomic(); },
79 EventBase::Delayed_Writeback_Pri
)
81 tempBlock
= new CacheBlk();
82 tempBlock
->data
= new uint8_t[blkSize
];
84 cpuSidePort
= new CpuSidePort(p
->name
+ ".cpu_side", this,
86 memSidePort
= new MemSidePort(p
->name
+ ".mem_side", this,
91 prefetcher
->setCache(this);
96 delete [] tempBlock
->data
;
106 BaseCache::regStats();
110 Cache::cmpAndSwap(CacheBlk
*blk
, PacketPtr pkt
)
112 assert(pkt
->isRequest());
114 uint64_t overwrite_val
;
116 uint64_t condition_val64
;
117 uint32_t condition_val32
;
119 int offset
= tags
->extractBlkOffset(pkt
->getAddr());
120 uint8_t *blk_data
= blk
->data
+ offset
;
122 assert(sizeof(uint64_t) >= pkt
->getSize());
124 overwrite_mem
= true;
125 // keep a copy of our possible write value, and copy what is at the
126 // memory address into the packet
127 pkt
->writeData((uint8_t *)&overwrite_val
);
128 pkt
->setData(blk_data
);
130 if (pkt
->req
->isCondSwap()) {
131 if (pkt
->getSize() == sizeof(uint64_t)) {
132 condition_val64
= pkt
->req
->getExtraData();
133 overwrite_mem
= !std::memcmp(&condition_val64
, blk_data
,
135 } else if (pkt
->getSize() == sizeof(uint32_t)) {
136 condition_val32
= (uint32_t)pkt
->req
->getExtraData();
137 overwrite_mem
= !std::memcmp(&condition_val32
, blk_data
,
140 panic("Invalid size for conditional read/write\n");
144 std::memcpy(blk_data
, &overwrite_val
, pkt
->getSize());
145 blk
->status
|= BlkDirty
;
151 Cache::satisfyRequest(PacketPtr pkt
, CacheBlk
*blk
,
152 bool deferred_response
, bool pending_downgrade
)
154 assert(pkt
->isRequest());
156 assert(blk
&& blk
->isValid());
157 // Occasionally this is not true... if we are a lower-level cache
158 // satisfying a string of Read and ReadEx requests from
159 // upper-level caches, a Read will mark the block as shared but we
160 // can satisfy a following ReadEx anyway since we can rely on the
161 // Read requester(s) to have buffered the ReadEx snoop and to
162 // invalidate their blocks after receiving them.
163 // assert(!pkt->needsWritable() || blk->isWritable());
164 assert(pkt
->getOffset(blkSize
) + pkt
->getSize() <= blkSize
);
166 // Check RMW operations first since both isRead() and
167 // isWrite() will be true for them
168 if (pkt
->cmd
== MemCmd::SwapReq
) {
169 cmpAndSwap(blk
, pkt
);
170 } else if (pkt
->isWrite()) {
171 // we have the block in a writable state and can go ahead,
172 // note that the line may be also be considered writable in
173 // downstream caches along the path to memory, but always
174 // Exclusive, and never Modified
175 assert(blk
->isWritable());
176 // Write or WriteLine at the first cache with block in writable state
177 if (blk
->checkWrite(pkt
)) {
178 pkt
->writeDataToBlock(blk
->data
, blkSize
);
180 // Always mark the line as dirty (and thus transition to the
181 // Modified state) even if we are a failed StoreCond so we
182 // supply data to any snoops that have appended themselves to
183 // this cache before knowing the store will fail.
184 blk
->status
|= BlkDirty
;
185 DPRINTF(CacheVerbose
, "%s for %s (write)\n", __func__
, pkt
->print());
186 } else if (pkt
->isRead()) {
188 blk
->trackLoadLocked(pkt
);
191 // all read responses have a data payload
192 assert(pkt
->hasRespData());
193 pkt
->setDataFromBlock(blk
->data
, blkSize
);
195 // determine if this read is from a (coherent) cache or not
196 if (pkt
->fromCache()) {
197 assert(pkt
->getSize() == blkSize
);
198 // special handling for coherent block requests from
199 // upper-level caches
200 if (pkt
->needsWritable()) {
202 assert(pkt
->cmd
== MemCmd::ReadExReq
||
203 pkt
->cmd
== MemCmd::SCUpgradeFailReq
);
204 assert(!pkt
->hasSharers());
206 // if we have a dirty copy, make sure the recipient
207 // keeps it marked dirty (in the modified state)
208 if (blk
->isDirty()) {
209 pkt
->setCacheResponding();
210 blk
->status
&= ~BlkDirty
;
212 } else if (blk
->isWritable() && !pending_downgrade
&&
213 !pkt
->hasSharers() &&
214 pkt
->cmd
!= MemCmd::ReadCleanReq
) {
215 // we can give the requester a writable copy on a read
217 // - we have a writable copy at this level (& below)
218 // - we don't have a pending snoop from below
219 // signaling another read request
220 // - no other cache above has a copy (otherwise it
221 // would have set hasSharers flag when
222 // snooping the packet)
223 // - the read has explicitly asked for a clean
225 if (blk
->isDirty()) {
226 // special considerations if we're owner:
227 if (!deferred_response
) {
228 // respond with the line in Modified state
229 // (cacheResponding set, hasSharers not set)
230 pkt
->setCacheResponding();
232 // if this cache is mostly inclusive, we
233 // keep the block in the Exclusive state,
234 // and pass it upwards as Modified
235 // (writable and dirty), hence we have
236 // multiple caches, all on the same path
237 // towards memory, all considering the
238 // same block writable, but only one
239 // considering it Modified
241 // we get away with multiple caches (on
242 // the same path to memory) considering
243 // the block writeable as we always enter
244 // the cache hierarchy through a cache,
245 // and first snoop upwards in all other
247 blk
->status
&= ~BlkDirty
;
249 // if we're responding after our own miss,
250 // there's a window where the recipient didn't
251 // know it was getting ownership and may not
252 // have responded to snoops correctly, so we
253 // have to respond with a shared line
254 pkt
->setHasSharers();
258 // otherwise only respond with a shared copy
259 pkt
->setHasSharers();
262 } else if (pkt
->isUpgrade()) {
264 assert(!pkt
->hasSharers());
266 if (blk
->isDirty()) {
267 // we were in the Owned state, and a cache above us that
268 // has the line in Shared state needs to be made aware
269 // that the data it already has is in fact dirty
270 pkt
->setCacheResponding();
271 blk
->status
&= ~BlkDirty
;
274 assert(pkt
->isInvalidate());
275 invalidateBlock(blk
);
276 DPRINTF(CacheVerbose
, "%s for %s (invalidation)\n", __func__
,
281 /////////////////////////////////////////////////////
283 // Access path: requests coming in from the CPU side
285 /////////////////////////////////////////////////////
288 Cache::access(PacketPtr pkt
, CacheBlk
*&blk
, Cycles
&lat
,
289 PacketList
&writebacks
)
292 assert(pkt
->isRequest());
294 chatty_assert(!(isReadOnly
&& pkt
->isWrite()),
295 "Should never see a write in a read-only cache %s\n",
298 DPRINTF(CacheVerbose
, "%s for %s\n", __func__
, pkt
->print());
300 if (pkt
->req
->isUncacheable()) {
301 DPRINTF(Cache
, "uncacheable: %s\n", pkt
->print());
303 // flush and invalidate any existing block
304 CacheBlk
*old_blk(tags
->findBlock(pkt
->getAddr(), pkt
->isSecure()));
305 if (old_blk
&& old_blk
->isValid()) {
306 if (old_blk
->isDirty() || writebackClean
)
307 writebacks
.push_back(writebackBlk(old_blk
));
309 writebacks
.push_back(cleanEvictBlk(old_blk
));
310 invalidateBlock(old_blk
);
314 // lookupLatency is the latency in case the request is uncacheable.
319 // Here lat is the value passed as parameter to accessBlock() function
320 // that can modify its value.
321 blk
= tags
->accessBlock(pkt
->getAddr(), pkt
->isSecure(), lat
);
323 DPRINTF(Cache
, "%s %s\n", pkt
->print(),
324 blk
? "hit " + blk
->print() : "miss");
326 if (pkt
->req
->isCacheMaintenance()) {
327 // A cache maintenance operation is always forwarded to the
328 // memory below even if the block is found in dirty state.
330 // We defer any changes to the state of the block until we
331 // create and mark as in service the mshr for the downstream
336 if (pkt
->isEviction()) {
337 // We check for presence of block in above caches before issuing
338 // Writeback or CleanEvict to write buffer. Therefore the only
339 // possible cases can be of a CleanEvict packet coming from above
340 // encountering a Writeback generated in this cache peer cache and
341 // waiting in the write buffer. Cases of upper level peer caches
342 // generating CleanEvict and Writeback or simply CleanEvict and
343 // CleanEvict almost simultaneously will be caught by snoops sent out
345 WriteQueueEntry
*wb_entry
= writeBuffer
.findMatch(pkt
->getAddr(),
348 assert(wb_entry
->getNumTargets() == 1);
349 PacketPtr wbPkt
= wb_entry
->getTarget()->pkt
;
350 assert(wbPkt
->isWriteback());
352 if (pkt
->isCleanEviction()) {
353 // The CleanEvict and WritebackClean snoops into other
354 // peer caches of the same level while traversing the
355 // crossbar. If a copy of the block is found, the
356 // packet is deleted in the crossbar. Hence, none of
357 // the other upper level caches connected to this
358 // cache have the block, so we can clear the
359 // BLOCK_CACHED flag in the Writeback if set and
360 // discard the CleanEvict by returning true.
361 wbPkt
->clearBlockCached();
364 assert(pkt
->cmd
== MemCmd::WritebackDirty
);
365 // Dirty writeback from above trumps our clean
366 // writeback... discard here
367 // Note: markInService will remove entry from writeback buffer.
368 markInService(wb_entry
);
374 // Writeback handling is special case. We can write the block into
375 // the cache without having a writeable copy (or any copy at all).
376 if (pkt
->isWriteback()) {
377 assert(blkSize
== pkt
->getSize());
379 // we could get a clean writeback while we are having
380 // outstanding accesses to a block, do the simple thing for
381 // now and drop the clean writeback so that we do not upset
382 // any ordering/decisions about ownership already taken
383 if (pkt
->cmd
== MemCmd::WritebackClean
&&
384 mshrQueue
.findMatch(pkt
->getAddr(), pkt
->isSecure())) {
385 DPRINTF(Cache
, "Clean writeback %#llx to block with MSHR, "
386 "dropping\n", pkt
->getAddr());
390 if (blk
== nullptr) {
391 // need to do a replacement
392 blk
= allocateBlock(pkt
->getAddr(), pkt
->isSecure(), writebacks
);
393 if (blk
== nullptr) {
394 // no replaceable block available: give up, fwd to next level.
398 tags
->insertBlock(pkt
, blk
);
400 blk
->status
|= (BlkValid
| BlkReadable
);
402 // only mark the block dirty if we got a writeback command,
403 // and leave it as is for a clean writeback
404 if (pkt
->cmd
== MemCmd::WritebackDirty
) {
405 assert(!blk
->isDirty());
406 blk
->status
|= BlkDirty
;
408 // if the packet does not have sharers, it is passing
409 // writable, and we got the writeback in Modified or Exclusive
410 // state, if not we are in the Owned or Shared state
411 if (!pkt
->hasSharers()) {
412 blk
->status
|= BlkWritable
;
414 // nothing else to do; writeback doesn't expect response
415 assert(!pkt
->needsResponse());
416 pkt
->writeDataToBlock(blk
->data
, blkSize
);
417 DPRINTF(Cache
, "%s new state is %s\n", __func__
, blk
->print());
419 // populate the time when the block will be ready to access.
420 blk
->whenReady
= clockEdge(fillLatency
) + pkt
->headerDelay
+
423 } else if (pkt
->cmd
== MemCmd::CleanEvict
) {
424 if (blk
!= nullptr) {
425 // Found the block in the tags, need to stop CleanEvict from
426 // propagating further down the hierarchy. Returning true will
427 // treat the CleanEvict like a satisfied write request and delete
431 // We didn't find the block here, propagate the CleanEvict further
432 // down the memory hierarchy. Returning false will treat the CleanEvict
433 // like a Writeback which could not find a replaceable block so has to
436 } else if (pkt
->cmd
== MemCmd::WriteClean
) {
437 // WriteClean handling is a special case. We can allocate a
438 // block directly if it doesn't exist and we can update the
439 // block immediately. The WriteClean transfers the ownership
440 // of the block as well.
441 assert(blkSize
== pkt
->getSize());
444 if (pkt
->writeThrough()) {
445 // if this is a write through packet, we don't try to
446 // allocate if the block is not present
449 // a writeback that misses needs to allocate a new block
450 blk
= allocateBlock(pkt
->getAddr(), pkt
->isSecure(),
453 // no replaceable block available: give up, fwd to
458 tags
->insertBlock(pkt
, blk
);
460 blk
->status
|= (BlkValid
| BlkReadable
);
464 // at this point either this is a writeback or a write-through
465 // write clean operation and the block is already in this
466 // cache, we need to update the data and the block flags
468 assert(!blk
->isDirty());
469 if (!pkt
->writeThrough()) {
470 blk
->status
|= BlkDirty
;
472 // nothing else to do; writeback doesn't expect response
473 assert(!pkt
->needsResponse());
474 pkt
->writeDataToBlock(blk
->data
, blkSize
);
475 DPRINTF(Cache
, "%s new state is %s\n", __func__
, blk
->print());
478 // populate the time when the block will be ready to access.
479 blk
->whenReady
= clockEdge(fillLatency
) + pkt
->headerDelay
+
481 // if this a write-through packet it will be sent to cache
483 return !pkt
->writeThrough();
484 } else if (blk
&& (pkt
->needsWritable() ? blk
->isWritable() :
485 blk
->isReadable())) {
486 // OK to satisfy access
488 satisfyRequest(pkt
, blk
);
489 maintainClusivity(pkt
->fromCache(), blk
);
494 // Can't satisfy access normally... either no block (blk == nullptr)
495 // or have block but need writable
499 if (blk
== nullptr && pkt
->isLLSC() && pkt
->isWrite()) {
500 // complete miss on store conditional... just give up now
501 pkt
->req
->setExtraData(0);
509 Cache::maintainClusivity(bool from_cache
, CacheBlk
*blk
)
511 if (from_cache
&& blk
&& blk
->isValid() && !blk
->isDirty() &&
512 clusivity
== Enums::mostly_excl
) {
513 // if we have responded to a cache, and our block is still
514 // valid, but not dirty, and this cache is mostly exclusive
515 // with respect to the cache above, drop the block
516 invalidateBlock(blk
);
521 Cache::doWritebacks(PacketList
& writebacks
, Tick forward_time
)
523 while (!writebacks
.empty()) {
524 PacketPtr wbPkt
= writebacks
.front();
525 // We use forwardLatency here because we are copying writebacks to
528 // Call isCachedAbove for Writebacks, CleanEvicts and
529 // WriteCleans to discover if the block is cached above.
530 if (isCachedAbove(wbPkt
)) {
531 if (wbPkt
->cmd
== MemCmd::CleanEvict
) {
532 // Delete CleanEvict because cached copies exist above. The
533 // packet destructor will delete the request object because
534 // this is a non-snoop request packet which does not require a
537 } else if (wbPkt
->cmd
== MemCmd::WritebackClean
) {
538 // clean writeback, do not send since the block is
539 // still cached above
540 assert(writebackClean
);
543 assert(wbPkt
->cmd
== MemCmd::WritebackDirty
||
544 wbPkt
->cmd
== MemCmd::WriteClean
);
545 // Set BLOCK_CACHED flag in Writeback and send below, so that
546 // the Writeback does not reset the bit corresponding to this
547 // address in the snoop filter below.
548 wbPkt
->setBlockCached();
549 allocateWriteBuffer(wbPkt
, forward_time
);
552 // If the block is not cached above, send packet below. Both
553 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
554 // reset the bit corresponding to this address in the snoop filter
556 allocateWriteBuffer(wbPkt
, forward_time
);
558 writebacks
.pop_front();
563 Cache::doWritebacksAtomic(PacketList
& writebacks
)
565 while (!writebacks
.empty()) {
566 PacketPtr wbPkt
= writebacks
.front();
567 // Call isCachedAbove for both Writebacks and CleanEvicts. If
568 // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
569 // and discard CleanEvicts.
570 if (isCachedAbove(wbPkt
, false)) {
571 if (wbPkt
->cmd
== MemCmd::WritebackDirty
||
572 wbPkt
->cmd
== MemCmd::WriteClean
) {
573 // Set BLOCK_CACHED flag in Writeback and send below,
574 // so that the Writeback does not reset the bit
575 // corresponding to this address in the snoop filter
576 // below. We can discard CleanEvicts because cached
577 // copies exist above. Atomic mode isCachedAbove
578 // modifies packet to set BLOCK_CACHED flag
579 memSidePort
->sendAtomic(wbPkt
);
582 // If the block is not cached above, send packet below. Both
583 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
584 // reset the bit corresponding to this address in the snoop filter
586 memSidePort
->sendAtomic(wbPkt
);
588 writebacks
.pop_front();
589 // In case of CleanEvicts, the packet destructor will delete the
590 // request object because this is a non-snoop request packet which
591 // does not require a response.
598 Cache::recvTimingSnoopResp(PacketPtr pkt
)
600 DPRINTF(Cache
, "%s for %s\n", __func__
, pkt
->print());
602 assert(pkt
->isResponse());
603 assert(!system
->bypassCaches());
605 // determine if the response is from a snoop request we created
606 // (in which case it should be in the outstandingSnoop), or if we
607 // merely forwarded someone else's snoop request
608 const bool forwardAsSnoop
= outstandingSnoop
.find(pkt
->req
) ==
609 outstandingSnoop
.end();
611 if (!forwardAsSnoop
) {
612 // the packet came from this cache, so sink it here and do not
614 assert(pkt
->cmd
== MemCmd::HardPFResp
);
616 outstandingSnoop
.erase(pkt
->req
);
618 DPRINTF(Cache
, "Got prefetch response from above for addr "
619 "%#llx (%s)\n", pkt
->getAddr(), pkt
->isSecure() ? "s" : "ns");
624 // forwardLatency is set here because there is a response from an
625 // upper level cache.
626 // To pay the delay that occurs if the packet comes from the bus,
627 // we charge also headerDelay.
628 Tick snoop_resp_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
629 // Reset the timing of the packet.
630 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
631 memSidePort
->schedTimingSnoopResp(pkt
, snoop_resp_time
);
635 Cache::promoteWholeLineWrites(PacketPtr pkt
)
637 // Cache line clearing instructions
638 if (doFastWrites
&& (pkt
->cmd
== MemCmd::WriteReq
) &&
639 (pkt
->getSize() == blkSize
) && (pkt
->getOffset(blkSize
) == 0)) {
640 pkt
->cmd
= MemCmd::WriteLineReq
;
641 DPRINTF(Cache
, "packet promoted from Write to WriteLineReq\n");
646 Cache::handleTimingReqHit(PacketPtr pkt
, CacheBlk
*blk
, Tick request_time
)
648 // should never be satisfying an uncacheable access as we
649 // flush and invalidate any existing block as part of the
651 assert(!pkt
->req
->isUncacheable());
653 if (pkt
->needsResponse()) {
654 pkt
->makeTimingResponse();
655 // @todo: Make someone pay for this
656 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
658 // In this case we are considering request_time that takes
659 // into account the delay of the xbar, if any, and just
660 // lat, neglecting responseLatency, modelling hit latency
661 // just as lookupLatency or or the value of lat overriden
662 // by access(), that calls accessBlock() function.
663 cpuSidePort
->schedTimingResp(pkt
, request_time
, true);
665 DPRINTF(Cache
, "%s satisfied %s, no response needed\n", __func__
,
668 // queue the packet for deletion, as the sending cache is
669 // still relying on it; if the block is found in access(),
670 // CleanEvict and Writeback messages will be deleted
672 pendingDelete
.reset(pkt
);
677 Cache::handleTimingReqMiss(PacketPtr pkt
, CacheBlk
*blk
, Tick forward_time
,
680 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
682 // ignore any existing MSHR if we are dealing with an
683 // uncacheable request
684 MSHR
*mshr
= pkt
->req
->isUncacheable() ? nullptr :
685 mshrQueue
.findMatch(blk_addr
, pkt
->isSecure());
687 // Software prefetch handling:
688 // To keep the core from waiting on data it won't look at
689 // anyway, send back a response with dummy data. Miss handling
690 // will continue asynchronously. Unfortunately, the core will
691 // insist upon freeing original Packet/Request, so we have to
692 // create a new pair with a different lifecycle. Note that this
693 // processing happens before any MSHR munging on the behalf of
694 // this request because this new Request will be the one stored
695 // into the MSHRs, not the original.
696 if (pkt
->cmd
.isSWPrefetch()) {
697 assert(pkt
->needsResponse());
698 assert(pkt
->req
->hasPaddr());
699 assert(!pkt
->req
->isUncacheable());
701 // There's no reason to add a prefetch as an additional target
702 // to an existing MSHR. If an outstanding request is already
703 // in progress, there is nothing for the prefetch to do.
704 // If this is the case, we don't even create a request at all.
705 PacketPtr pf
= nullptr;
708 // copy the request and create a new SoftPFReq packet
709 RequestPtr req
= new Request(pkt
->req
->getPaddr(),
711 pkt
->req
->getFlags(),
712 pkt
->req
->masterId());
713 pf
= new Packet(req
, pkt
->cmd
);
715 assert(pf
->getAddr() == pkt
->getAddr());
716 assert(pf
->getSize() == pkt
->getSize());
719 pkt
->makeTimingResponse();
721 // request_time is used here, taking into account lat and the delay
722 // charged if the packet comes from the xbar.
723 cpuSidePort
->schedTimingResp(pkt
, request_time
, true);
725 // If an outstanding request is in progress (we found an
726 // MSHR) this is set to null
732 /// @note writebacks will be checked in getNextMSHR()
733 /// for any conflicting requests to the same block
735 //@todo remove hw_pf here
737 // Coalesce unless it was a software prefetch (see above).
739 assert(!pkt
->isWriteback());
740 // CleanEvicts corresponding to blocks which have
741 // outstanding requests in MSHRs are simply sunk here
742 if (pkt
->cmd
== MemCmd::CleanEvict
) {
743 pendingDelete
.reset(pkt
);
744 } else if (pkt
->cmd
== MemCmd::WriteClean
) {
745 // A WriteClean should never coalesce with any
746 // outstanding cache maintenance requests.
748 // We use forward_time here because there is an
749 // uncached memory write, forwarded to WriteBuffer.
750 allocateWriteBuffer(pkt
, forward_time
);
752 DPRINTF(Cache
, "%s coalescing MSHR for %s\n", __func__
,
755 assert(pkt
->req
->masterId() < system
->maxMasters());
756 mshr_hits
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
758 // uncacheable accesses always allocate a new
759 // MSHR, and cacheable accesses ignore any
760 // uncacheable MSHRs, thus we should never have
761 // targets addded if originally allocated
763 assert(!mshr
->isUncacheable());
765 // We use forward_time here because it is the same
766 // considering new targets. We have multiple
767 // requests for the same address here. It
768 // specifies the latency to allocate an internal
769 // buffer and to schedule an event to the queued
770 // port and also takes into account the additional
771 // delay of the xbar.
772 mshr
->allocateTarget(pkt
, forward_time
, order
++,
773 allocOnFill(pkt
->cmd
));
774 if (mshr
->getNumTargets() == numTarget
) {
776 setBlocked(Blocked_NoTargets
);
777 // need to be careful with this... if this mshr isn't
778 // ready yet (i.e. time > curTick()), we don't want to
779 // move it ahead of mshrs that are ready
780 // mshrQueue.moveToFront(mshr);
786 assert(pkt
->req
->masterId() < system
->maxMasters());
787 if (pkt
->req
->isUncacheable()) {
788 mshr_uncacheable
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
790 mshr_misses
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
793 if (pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
||
794 (pkt
->req
->isUncacheable() && pkt
->isWrite())) {
795 // We use forward_time here because there is an
796 // uncached memory write, forwarded to WriteBuffer.
797 allocateWriteBuffer(pkt
, forward_time
);
799 if (blk
&& blk
->isValid()) {
800 // should have flushed and have no valid block
801 assert(!pkt
->req
->isUncacheable());
803 // If we have a write miss to a valid block, we
804 // need to mark the block non-readable. Otherwise
805 // if we allow reads while there's an outstanding
806 // write miss, the read could return stale data
807 // out of the cache block... a more aggressive
808 // system could detect the overlap (if any) and
809 // forward data out of the MSHRs, but we don't do
810 // that yet. Note that we do need to leave the
811 // block valid so that it stays in the cache, in
812 // case we get an upgrade response (and hence no
813 // new data) when the write miss completes.
814 // As long as CPUs do proper store/load forwarding
815 // internally, and have a sufficiently weak memory
816 // model, this is probably unnecessary, but at some
817 // point it must have seemed like we needed it...
818 assert((pkt
->needsWritable() && !blk
->isWritable()) ||
819 pkt
->req
->isCacheMaintenance());
820 blk
->status
&= ~BlkReadable
;
822 // Here we are using forward_time, modelling the latency of
823 // a miss (outbound) just as forwardLatency, neglecting the
824 // lookupLatency component.
825 allocateMissBuffer(pkt
, forward_time
);
831 Cache::recvTimingReq(PacketPtr pkt
)
833 DPRINTF(CacheTags
, "%s tags:\n%s\n", __func__
, tags
->print());
835 assert(pkt
->isRequest());
837 // Just forward the packet if caches are disabled.
838 if (system
->bypassCaches()) {
839 // @todo This should really enqueue the packet rather
840 bool M5_VAR_USED success
= memSidePort
->sendTimingReq(pkt
);
845 promoteWholeLineWrites(pkt
);
847 // Cache maintenance operations have to visit all the caches down
848 // to the specified xbar (PoC, PoU, etc.). Even if a cache above
849 // is responding we forward the packet to the memory below rather
850 // than creating an express snoop.
851 if (pkt
->cacheResponding()) {
852 // a cache above us (but not where the packet came from) is
853 // responding to the request, in other words it has the line
854 // in Modified or Owned state
855 DPRINTF(Cache
, "Cache above responding to %s: not responding\n",
858 // if the packet needs the block to be writable, and the cache
859 // that has promised to respond (setting the cache responding
860 // flag) is not providing writable (it is in Owned rather than
861 // the Modified state), we know that there may be other Shared
862 // copies in the system; go out and invalidate them all
863 assert(pkt
->needsWritable() && !pkt
->responderHadWritable());
865 // an upstream cache that had the line in Owned state
866 // (dirty, but not writable), is responding and thus
867 // transferring the dirty line from one branch of the
868 // cache hierarchy to another
870 // send out an express snoop and invalidate all other
871 // copies (snooping a packet that needs writable is the
872 // same as an invalidation), thus turning the Owned line
873 // into a Modified line, note that we don't invalidate the
874 // block in the current cache or any other cache on the
877 // create a downstream express snoop with cleared packet
878 // flags, there is no need to allocate any data as the
879 // packet is merely used to co-ordinate state transitions
880 Packet
*snoop_pkt
= new Packet(pkt
, true, false);
882 // also reset the bus time that the original packet has
884 snoop_pkt
->headerDelay
= snoop_pkt
->payloadDelay
= 0;
886 // make this an instantaneous express snoop, and let the
887 // other caches in the system know that the another cache
888 // is responding, because we have found the authorative
889 // copy (Modified or Owned) that will supply the right
891 snoop_pkt
->setExpressSnoop();
892 snoop_pkt
->setCacheResponding();
894 // this express snoop travels towards the memory, and at
895 // every crossbar it is snooped upwards thus reaching
896 // every cache in the system
897 bool M5_VAR_USED success
= memSidePort
->sendTimingReq(snoop_pkt
);
898 // express snoops always succeed
901 // main memory will delete the snoop packet
903 // queue for deletion, as opposed to immediate deletion, as
904 // the sending cache is still relying on the packet
905 pendingDelete
.reset(pkt
);
907 // no need to take any further action in this particular cache
908 // as an upstram cache has already committed to responding,
909 // and we have already sent out any express snoops in the
910 // section above to ensure all other copies in the system are
915 // anything that is merely forwarded pays for the forward latency and
916 // the delay provided by the crossbar
917 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
919 // We use lookupLatency here because it is used to specify the latency
921 Cycles lat
= lookupLatency
;
922 CacheBlk
*blk
= nullptr;
923 bool satisfied
= false;
925 PacketList writebacks
;
926 // Note that lat is passed by reference here. The function
927 // access() calls accessBlock() which can modify lat value.
928 satisfied
= access(pkt
, blk
, lat
, writebacks
);
930 // copy writebacks to write buffer here to ensure they logically
931 // proceed anything happening below
932 doWritebacks(writebacks
, forward_time
);
935 // Here we charge the headerDelay that takes into account the latencies
936 // of the bus, if the packet comes from it.
937 // The latency charged it is just lat that is the value of lookupLatency
938 // modified by access() function, or if not just lookupLatency.
939 // In case of a hit we are neglecting response latency.
940 // In case of a miss we are neglecting forward latency.
941 Tick request_time
= clockEdge(lat
) + pkt
->headerDelay
;
942 // Here we reset the timing of the packet.
943 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
945 // track time of availability of next prefetch, if any
946 Tick next_pf_time
= MaxTick
;
949 // if need to notify the prefetcher we need to do it anything
950 // else, handleTimingReqHit might turn the packet into a
953 (prefetchOnAccess
|| (blk
&& blk
->wasPrefetched()))) {
955 blk
->status
&= ~BlkHWPrefetched
;
957 // Don't notify on SWPrefetch
958 if (!pkt
->cmd
.isSWPrefetch()) {
959 assert(!pkt
->req
->isCacheMaintenance());
960 next_pf_time
= prefetcher
->notify(pkt
);
964 handleTimingReqHit(pkt
, blk
, request_time
);
966 handleTimingReqMiss(pkt
, blk
, forward_time
, request_time
);
968 // We should call the prefetcher reguardless if the request is
969 // satisfied or not, reguardless if the request is in the MSHR
970 // or not. The request could be a ReadReq hit, but still not
971 // satisfied (potentially because of a prior write to the same
972 // cache line. So, even when not satisfied, there is an MSHR
973 // already allocated for this, we need to let the prefetcher
974 // know about the request
975 if (prefetcher
&& pkt
&&
976 !pkt
->cmd
.isSWPrefetch() &&
977 !pkt
->req
->isCacheMaintenance()) {
978 next_pf_time
= prefetcher
->notify(pkt
);
982 if (next_pf_time
!= MaxTick
)
983 schedMemSideSendEvent(next_pf_time
);
987 Cache::createMissPacket(PacketPtr cpu_pkt
, CacheBlk
*blk
,
988 bool needsWritable
) const
990 // should never see evictions here
991 assert(!cpu_pkt
->isEviction());
993 bool blkValid
= blk
&& blk
->isValid();
995 if (cpu_pkt
->req
->isUncacheable() ||
996 (!blkValid
&& cpu_pkt
->isUpgrade()) ||
997 cpu_pkt
->cmd
== MemCmd::InvalidateReq
|| cpu_pkt
->isClean()) {
998 // uncacheable requests and upgrades from upper-level caches
999 // that missed completely just go through as is
1003 assert(cpu_pkt
->needsResponse());
1006 // @TODO make useUpgrades a parameter.
1007 // Note that ownership protocols require upgrade, otherwise a
1008 // write miss on a shared owned block will generate a ReadExcl,
1009 // which will clobber the owned copy.
1010 const bool useUpgrades
= true;
1011 if (cpu_pkt
->cmd
== MemCmd::WriteLineReq
) {
1012 assert(!blkValid
|| !blk
->isWritable());
1013 // forward as invalidate to all other caches, this gives us
1014 // the line in Exclusive state, and invalidates all other
1016 cmd
= MemCmd::InvalidateReq
;
1017 } else if (blkValid
&& useUpgrades
) {
1018 // only reason to be here is that blk is read only and we need
1019 // it to be writable
1020 assert(needsWritable
);
1021 assert(!blk
->isWritable());
1022 cmd
= cpu_pkt
->isLLSC() ? MemCmd::SCUpgradeReq
: MemCmd::UpgradeReq
;
1023 } else if (cpu_pkt
->cmd
== MemCmd::SCUpgradeFailReq
||
1024 cpu_pkt
->cmd
== MemCmd::StoreCondFailReq
) {
1025 // Even though this SC will fail, we still need to send out the
1026 // request and get the data to supply it to other snoopers in the case
1027 // where the determination the StoreCond fails is delayed due to
1028 // all caches not being on the same local bus.
1029 cmd
= MemCmd::SCUpgradeFailReq
;
1033 // If the request does not need a writable there are two cases
1034 // where we need to ensure the response will not fetch the
1035 // block in dirty state:
1036 // * this cache is read only and it does not perform
1038 // * this cache is mostly exclusive and will not fill (since
1039 // it does not fill it will have to writeback the dirty data
1040 // immediately which generates uneccesary writebacks).
1041 bool force_clean_rsp
= isReadOnly
|| clusivity
== Enums::mostly_excl
;
1042 cmd
= needsWritable
? MemCmd::ReadExReq
:
1043 (force_clean_rsp
? MemCmd::ReadCleanReq
: MemCmd::ReadSharedReq
);
1045 PacketPtr pkt
= new Packet(cpu_pkt
->req
, cmd
, blkSize
);
1047 // if there are upstream caches that have already marked the
1048 // packet as having sharers (not passing writable), pass that info
1050 if (cpu_pkt
->hasSharers() && !needsWritable
) {
1051 // note that cpu_pkt may have spent a considerable time in the
1052 // MSHR queue and that the information could possibly be out
1053 // of date, however, there is no harm in conservatively
1054 // assuming the block has sharers
1055 pkt
->setHasSharers();
1056 DPRINTF(Cache
, "%s: passing hasSharers from %s to %s\n",
1057 __func__
, cpu_pkt
->print(), pkt
->print());
1060 // the packet should be block aligned
1061 assert(pkt
->getAddr() == pkt
->getBlockAddr(blkSize
));
1064 DPRINTF(Cache
, "%s: created %s from %s\n", __func__
, pkt
->print(),
1071 Cache::handleAtomicReqMiss(PacketPtr pkt
, CacheBlk
*blk
,
1072 PacketList
&writebacks
)
1074 // deal with the packets that go through the write path of
1075 // the cache, i.e. any evictions and writes
1076 if (pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
||
1077 (pkt
->req
->isUncacheable() && pkt
->isWrite())) {
1078 Cycles latency
= ticksToCycles(memSidePort
->sendAtomic(pkt
));
1080 // at this point, if the request was an uncacheable write
1081 // request, it has been satisfied by a memory below and the
1082 // packet carries the response back
1083 assert(!(pkt
->req
->isUncacheable() && pkt
->isWrite()) ||
1091 PacketPtr bus_pkt
= createMissPacket(pkt
, blk
, pkt
->needsWritable());
1093 bool is_forward
= (bus_pkt
== nullptr);
1096 // just forwarding the same request to the next level
1097 // no local cache operation involved
1101 DPRINTF(Cache
, "%s: Sending an atomic %s\n", __func__
,
1105 CacheBlk::State old_state
= blk
? blk
->status
: 0;
1108 Cycles latency
= ticksToCycles(memSidePort
->sendAtomic(bus_pkt
));
1110 bool is_invalidate
= bus_pkt
->isInvalidate();
1112 // We are now dealing with the response handling
1113 DPRINTF(Cache
, "%s: Receive response: %s in state %i\n", __func__
,
1114 bus_pkt
->print(), old_state
);
1116 // If packet was a forward, the response (if any) is already
1117 // in place in the bus_pkt == pkt structure, so we don't need
1118 // to do anything. Otherwise, use the separate bus_pkt to
1119 // generate response to pkt and then delete it.
1121 if (pkt
->needsResponse()) {
1122 assert(bus_pkt
->isResponse());
1123 if (bus_pkt
->isError()) {
1124 pkt
->makeAtomicResponse();
1125 pkt
->copyError(bus_pkt
);
1126 } else if (pkt
->cmd
== MemCmd::WriteLineReq
) {
1127 // note the use of pkt, not bus_pkt here.
1129 // write-line request to the cache that promoted
1130 // the write to a whole line
1131 blk
= handleFill(pkt
, blk
, writebacks
,
1132 allocOnFill(pkt
->cmd
));
1133 assert(blk
!= NULL
);
1134 is_invalidate
= false;
1135 satisfyRequest(pkt
, blk
);
1136 } else if (bus_pkt
->isRead() ||
1137 bus_pkt
->cmd
== MemCmd::UpgradeResp
) {
1138 // we're updating cache state to allow us to
1139 // satisfy the upstream request from the cache
1140 blk
= handleFill(bus_pkt
, blk
, writebacks
,
1141 allocOnFill(pkt
->cmd
));
1142 satisfyRequest(pkt
, blk
);
1143 maintainClusivity(pkt
->fromCache(), blk
);
1145 // we're satisfying the upstream request without
1146 // modifying cache state, e.g., a write-through
1147 pkt
->makeAtomicResponse();
1153 if (is_invalidate
&& blk
&& blk
->isValid()) {
1154 invalidateBlock(blk
);
1161 Cache::recvAtomic(PacketPtr pkt
)
1163 // We are in atomic mode so we pay just for lookupLatency here.
1164 Cycles lat
= lookupLatency
;
1166 // Forward the request if the system is in cache bypass mode.
1167 if (system
->bypassCaches())
1168 return ticksToCycles(memSidePort
->sendAtomic(pkt
));
1170 promoteWholeLineWrites(pkt
);
1172 // follow the same flow as in recvTimingReq, and check if a cache
1173 // above us is responding
1174 if (pkt
->cacheResponding() && !pkt
->isClean()) {
1175 assert(!pkt
->req
->isCacheInvalidate());
1176 DPRINTF(Cache
, "Cache above responding to %s: not responding\n",
1179 // if a cache is responding, and it had the line in Owned
1180 // rather than Modified state, we need to invalidate any
1181 // copies that are not on the same path to memory
1182 assert(pkt
->needsWritable() && !pkt
->responderHadWritable());
1183 lat
+= ticksToCycles(memSidePort
->sendAtomic(pkt
));
1185 return lat
* clockPeriod();
1188 // should assert here that there are no outstanding MSHRs or
1189 // writebacks... that would mean that someone used an atomic
1190 // access in timing mode
1192 CacheBlk
*blk
= nullptr;
1193 PacketList writebacks
;
1194 bool satisfied
= access(pkt
, blk
, lat
, writebacks
);
1196 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
1197 // A cache clean opearation is looking for a dirty
1198 // block. If a dirty block is encountered a WriteClean
1199 // will update any copies to the path to the memory
1200 // until the point of reference.
1201 DPRINTF(CacheVerbose
, "%s: packet %s found block: %s\n",
1202 __func__
, pkt
->print(), blk
->print());
1203 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest(), pkt
->id
);
1204 writebacks
.push_back(wb_pkt
);
1205 pkt
->setSatisfied();
1208 // handle writebacks resulting from the access here to ensure they
1209 // logically proceed anything happening below
1210 doWritebacksAtomic(writebacks
);
1211 assert(writebacks
.empty());
1214 lat
+= handleAtomicReqMiss(pkt
, blk
, writebacks
);
1217 // Note that we don't invoke the prefetcher at all in atomic mode.
1218 // It's not clear how to do it properly, particularly for
1219 // prefetchers that aggressively generate prefetch candidates and
1220 // rely on bandwidth contention to throttle them; these will tend
1221 // to pollute the cache in atomic mode since there is no bandwidth
1222 // contention. If we ever do want to enable prefetching in atomic
1223 // mode, though, this is the place to do it... see timingAccess()
1224 // for an example (though we'd want to issue the prefetch(es)
1225 // immediately rather than calling requestMemSideBus() as we do
1228 // do any writebacks resulting from the response handling
1229 doWritebacksAtomic(writebacks
);
1231 // if we used temp block, check to see if its valid and if so
1232 // clear it out, but only do so after the call to recvAtomic is
1233 // finished so that any downstream observers (such as a snoop
1234 // filter), first see the fill, and only then see the eviction
1235 if (blk
== tempBlock
&& tempBlock
->isValid()) {
1236 // the atomic CPU calls recvAtomic for fetch and load/store
1237 // sequentuially, and we may already have a tempBlock
1238 // writeback from the fetch that we have not yet sent
1239 if (tempBlockWriteback
) {
1240 // if that is the case, write the prevoius one back, and
1241 // do not schedule any new event
1242 writebackTempBlockAtomic();
1244 // the writeback/clean eviction happens after the call to
1245 // recvAtomic has finished (but before any successive
1246 // calls), so that the response handling from the fill is
1247 // allowed to happen first
1248 schedule(writebackTempBlockAtomicEvent
, curTick());
1251 tempBlockWriteback
= (blk
->isDirty() || writebackClean
) ?
1252 writebackBlk(blk
) : cleanEvictBlk(blk
);
1253 invalidateBlock(blk
);
1256 if (pkt
->needsResponse()) {
1257 pkt
->makeAtomicResponse();
1260 return lat
* clockPeriod();
1265 Cache::functionalAccess(PacketPtr pkt
, bool fromCpuSide
)
1267 if (system
->bypassCaches()) {
1268 // Packets from the memory side are snoop request and
1269 // shouldn't happen in bypass mode.
1270 assert(fromCpuSide
);
1272 // The cache should be flushed if we are in cache bypass mode,
1273 // so we don't need to check if we need to update anything.
1274 memSidePort
->sendFunctional(pkt
);
1278 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
1279 bool is_secure
= pkt
->isSecure();
1280 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), is_secure
);
1281 MSHR
*mshr
= mshrQueue
.findMatch(blk_addr
, is_secure
);
1283 pkt
->pushLabel(name());
1285 CacheBlkPrintWrapper
cbpw(blk
);
1287 // Note that just because an L2/L3 has valid data doesn't mean an
1288 // L1 doesn't have a more up-to-date modified copy that still
1289 // needs to be found. As a result we always update the request if
1290 // we have it, but only declare it satisfied if we are the owner.
1292 // see if we have data at all (owned or otherwise)
1293 bool have_data
= blk
&& blk
->isValid()
1294 && pkt
->checkFunctional(&cbpw
, blk_addr
, is_secure
, blkSize
,
1297 // data we have is dirty if marked as such or if we have an
1298 // in-service MSHR that is pending a modified line
1300 have_data
&& (blk
->isDirty() ||
1301 (mshr
&& mshr
->inService
&& mshr
->isPendingModified()));
1303 bool done
= have_dirty
1304 || cpuSidePort
->checkFunctional(pkt
)
1305 || mshrQueue
.checkFunctional(pkt
, blk_addr
)
1306 || writeBuffer
.checkFunctional(pkt
, blk_addr
)
1307 || memSidePort
->checkFunctional(pkt
);
1309 DPRINTF(CacheVerbose
, "%s: %s %s%s%s\n", __func__
, pkt
->print(),
1310 (blk
&& blk
->isValid()) ? "valid " : "",
1311 have_data
? "data " : "", done
? "done " : "");
1313 // We're leaving the cache, so pop cache->name() label
1317 pkt
->makeResponse();
1319 // if it came as a request from the CPU side then make sure it
1320 // continues towards the memory side
1322 memSidePort
->sendFunctional(pkt
);
1323 } else if (cpuSidePort
->isSnooping()) {
1324 // if it came from the memory side, it must be a snoop request
1325 // and we should only forward it if we are forwarding snoops
1326 cpuSidePort
->sendFunctionalSnoop(pkt
);
1332 /////////////////////////////////////////////////////
1334 // Response handling: responses from the memory side
1336 /////////////////////////////////////////////////////
1340 Cache::handleUncacheableWriteResp(PacketPtr pkt
)
1342 Tick completion_time
= clockEdge(responseLatency
) +
1343 pkt
->headerDelay
+ pkt
->payloadDelay
;
1345 // Reset the bus additional time as it is now accounted for
1346 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
1348 cpuSidePort
->schedTimingResp(pkt
, completion_time
, true);
1352 Cache::serviceMSHRTargets(MSHR
*mshr
, const PacketPtr pkt
, CacheBlk
*blk
,
1353 PacketList
&writebacks
)
1355 MSHR::Target
*initial_tgt
= mshr
->getTarget();
1356 // First offset for critical word first calculations
1357 const int initial_offset
= initial_tgt
->pkt
->getOffset(blkSize
);
1359 const bool is_error
= pkt
->isError();
1360 bool is_fill
= !mshr
->isForward
&&
1361 (pkt
->isRead() || pkt
->cmd
== MemCmd::UpgradeResp
);
1362 // allow invalidation responses originating from write-line
1363 // requests to be discarded
1364 bool is_invalidate
= pkt
->isInvalidate();
1366 MSHR::TargetList targets
= mshr
->extractServiceableTargets(pkt
);
1367 for (auto &target
: targets
) {
1368 Packet
*tgt_pkt
= target
.pkt
;
1369 switch (target
.source
) {
1370 case MSHR::Target::FromCPU
:
1371 Tick completion_time
;
1372 // Here we charge on completion_time the delay of the xbar if the
1373 // packet comes from it, charged on headerDelay.
1374 completion_time
= pkt
->headerDelay
;
1376 // Software prefetch handling for cache closest to core
1377 if (tgt_pkt
->cmd
.isSWPrefetch()) {
1378 // a software prefetch would have already been ack'd
1379 // immediately with dummy data so the core would be able to
1380 // retire it. This request completes right here, so we
1382 delete tgt_pkt
->req
;
1384 break; // skip response
1387 // unlike the other packet flows, where data is found in other
1388 // caches or memory and brought back, write-line requests always
1389 // have the data right away, so the above check for "is fill?"
1390 // cannot actually be determined until examining the stored MSHR
1391 // state. We "catch up" with that logic here, which is duplicated
1393 if (tgt_pkt
->cmd
== MemCmd::WriteLineReq
) {
1395 // we got the block in a writable state, so promote
1396 // any deferred targets if possible
1397 mshr
->promoteWritable();
1398 // NB: we use the original packet here and not the response!
1399 blk
= handleFill(tgt_pkt
, blk
, writebacks
,
1400 targets
.allocOnFill
);
1403 // treat as a fill, and discard the invalidation
1406 is_invalidate
= false;
1410 satisfyRequest(tgt_pkt
, blk
, true, mshr
->hasPostDowngrade());
1412 // How many bytes past the first request is this one
1413 int transfer_offset
=
1414 tgt_pkt
->getOffset(blkSize
) - initial_offset
;
1415 if (transfer_offset
< 0) {
1416 transfer_offset
+= blkSize
;
1419 // If not critical word (offset) return payloadDelay.
1420 // responseLatency is the latency of the return path
1421 // from lower level caches/memory to an upper level cache or
1423 completion_time
+= clockEdge(responseLatency
) +
1424 (transfer_offset
? pkt
->payloadDelay
: 0);
1426 assert(!tgt_pkt
->req
->isUncacheable());
1428 assert(tgt_pkt
->req
->masterId() < system
->maxMasters());
1429 missLatency
[tgt_pkt
->cmdToIndex()][tgt_pkt
->req
->masterId()] +=
1430 completion_time
- target
.recvTime
;
1431 } else if (pkt
->cmd
== MemCmd::UpgradeFailResp
) {
1432 // failed StoreCond upgrade
1433 assert(tgt_pkt
->cmd
== MemCmd::StoreCondReq
||
1434 tgt_pkt
->cmd
== MemCmd::StoreCondFailReq
||
1435 tgt_pkt
->cmd
== MemCmd::SCUpgradeFailReq
);
1436 // responseLatency is the latency of the return path
1437 // from lower level caches/memory to an upper level cache or
1439 completion_time
+= clockEdge(responseLatency
) +
1441 tgt_pkt
->req
->setExtraData(0);
1443 // We are about to send a response to a cache above
1444 // that asked for an invalidation; we need to
1445 // invalidate our copy immediately as the most
1446 // up-to-date copy of the block will now be in the
1447 // cache above. It will also prevent this cache from
1448 // responding (if the block was previously dirty) to
1449 // snoops as they should snoop the caches above where
1450 // they will get the response from.
1451 if (is_invalidate
&& blk
&& blk
->isValid()) {
1452 invalidateBlock(blk
);
1454 // not a cache fill, just forwarding response
1455 // responseLatency is the latency of the return path
1456 // from lower level cahces/memory to the core.
1457 completion_time
+= clockEdge(responseLatency
) +
1459 if (pkt
->isRead() && !is_error
) {
1461 assert(pkt
->getAddr() == tgt_pkt
->getAddr());
1462 assert(pkt
->getSize() >= tgt_pkt
->getSize());
1464 tgt_pkt
->setData(pkt
->getConstPtr
<uint8_t>());
1467 tgt_pkt
->makeTimingResponse();
1468 // if this packet is an error copy that to the new packet
1470 tgt_pkt
->copyError(pkt
);
1471 if (tgt_pkt
->cmd
== MemCmd::ReadResp
&&
1472 (is_invalidate
|| mshr
->hasPostInvalidate())) {
1473 // If intermediate cache got ReadRespWithInvalidate,
1474 // propagate that. Response should not have
1475 // isInvalidate() set otherwise.
1476 tgt_pkt
->cmd
= MemCmd::ReadRespWithInvalidate
;
1477 DPRINTF(Cache
, "%s: updated cmd to %s\n", __func__
,
1480 // Reset the bus additional time as it is now accounted for
1481 tgt_pkt
->headerDelay
= tgt_pkt
->payloadDelay
= 0;
1482 cpuSidePort
->schedTimingResp(tgt_pkt
, completion_time
, true);
1485 case MSHR::Target::FromPrefetcher
:
1486 assert(tgt_pkt
->cmd
== MemCmd::HardPFReq
);
1488 blk
->status
|= BlkHWPrefetched
;
1489 delete tgt_pkt
->req
;
1493 case MSHR::Target::FromSnoop
:
1494 // I don't believe that a snoop can be in an error state
1496 // response to snoop request
1497 DPRINTF(Cache
, "processing deferred snoop...\n");
1498 // If the response is invalidating, a snooping target can
1499 // be satisfied if it is also invalidating. If the reponse is, not
1500 // only invalidating, but more specifically an InvalidateResp and
1501 // the MSHR was created due to an InvalidateReq then a cache above
1502 // is waiting to satisfy a WriteLineReq. In this case even an
1503 // non-invalidating snoop is added as a target here since this is
1504 // the ordering point. When the InvalidateResp reaches this cache,
1505 // the snooping target will snoop further the cache above with the
1507 assert(!is_invalidate
|| pkt
->cmd
== MemCmd::InvalidateResp
||
1508 pkt
->req
->isCacheMaintenance() ||
1509 mshr
->hasPostInvalidate());
1510 handleSnoop(tgt_pkt
, blk
, true, true, mshr
->hasPostInvalidate());
1514 panic("Illegal target->source enum %d\n", target
.source
);
1518 maintainClusivity(targets
.hasFromCache
, blk
);
1520 if (blk
&& blk
->isValid()) {
1521 // an invalidate response stemming from a write line request
1522 // should not invalidate the block, so check if the
1523 // invalidation should be discarded
1524 if (is_invalidate
|| mshr
->hasPostInvalidate()) {
1525 invalidateBlock(blk
);
1526 } else if (mshr
->hasPostDowngrade()) {
1527 blk
->status
&= ~BlkWritable
;
1533 Cache::recvTimingResp(PacketPtr pkt
)
1535 assert(pkt
->isResponse());
1537 // all header delay should be paid for by the crossbar, unless
1538 // this is a prefetch response from above
1539 panic_if(pkt
->headerDelay
!= 0 && pkt
->cmd
!= MemCmd::HardPFResp
,
1540 "%s saw a non-zero packet delay\n", name());
1542 const bool is_error
= pkt
->isError();
1545 DPRINTF(Cache
, "%s: Cache received %s with error\n", __func__
,
1549 DPRINTF(Cache
, "%s: Handling response %s\n", __func__
,
1552 // if this is a write, we should be looking at an uncacheable
1554 if (pkt
->isWrite()) {
1555 assert(pkt
->req
->isUncacheable());
1556 handleUncacheableWriteResp(pkt
);
1560 // we have dealt with any (uncacheable) writes above, from here on
1561 // we know we are dealing with an MSHR due to a miss or a prefetch
1562 MSHR
*mshr
= dynamic_cast<MSHR
*>(pkt
->popSenderState());
1565 if (mshr
== noTargetMSHR
) {
1566 // we always clear at least one target
1567 clearBlocked(Blocked_NoTargets
);
1568 noTargetMSHR
= nullptr;
1571 // Initial target is used just for stats
1572 MSHR::Target
*initial_tgt
= mshr
->getTarget();
1573 int stats_cmd_idx
= initial_tgt
->pkt
->cmdToIndex();
1574 Tick miss_latency
= curTick() - initial_tgt
->recvTime
;
1576 if (pkt
->req
->isUncacheable()) {
1577 assert(pkt
->req
->masterId() < system
->maxMasters());
1578 mshr_uncacheable_lat
[stats_cmd_idx
][pkt
->req
->masterId()] +=
1581 assert(pkt
->req
->masterId() < system
->maxMasters());
1582 mshr_miss_latency
[stats_cmd_idx
][pkt
->req
->masterId()] +=
1586 PacketList writebacks
;
1588 bool is_fill
= !mshr
->isForward
&&
1589 (pkt
->isRead() || pkt
->cmd
== MemCmd::UpgradeResp
);
1591 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), pkt
->isSecure());
1593 if (is_fill
&& !is_error
) {
1594 DPRINTF(Cache
, "Block for addr %#llx being updated in Cache\n",
1597 blk
= handleFill(pkt
, blk
, writebacks
, mshr
->allocOnFill());
1598 assert(blk
!= nullptr);
1601 if (blk
&& blk
->isValid() && pkt
->isClean() && !pkt
->isInvalidate()) {
1602 // The block was marked not readable while there was a pending
1603 // cache maintenance operation, restore its flag.
1604 blk
->status
|= BlkReadable
;
1607 if (blk
&& blk
->isWritable() && !pkt
->req
->isCacheInvalidate()) {
1608 // If at this point the referenced block is writable and the
1609 // response is not a cache invalidate, we promote targets that
1610 // were deferred as we couldn't guarrantee a writable copy
1611 mshr
->promoteWritable();
1614 serviceMSHRTargets(mshr
, pkt
, blk
, writebacks
);
1616 if (mshr
->promoteDeferredTargets()) {
1617 // avoid later read getting stale data while write miss is
1618 // outstanding.. see comment in timingAccess()
1620 blk
->status
&= ~BlkReadable
;
1622 mshrQueue
.markPending(mshr
);
1623 schedMemSideSendEvent(clockEdge() + pkt
->payloadDelay
);
1625 // while we deallocate an mshr from the queue we still have to
1626 // check the isFull condition before and after as we might
1627 // have been using the reserved entries already
1628 const bool was_full
= mshrQueue
.isFull();
1629 mshrQueue
.deallocate(mshr
);
1630 if (was_full
&& !mshrQueue
.isFull()) {
1631 clearBlocked(Blocked_NoMSHRs
);
1634 // Request the bus for a prefetch if this deallocation freed enough
1635 // MSHRs for a prefetch to take place
1636 if (prefetcher
&& mshrQueue
.canPrefetch()) {
1637 Tick next_pf_time
= std::max(prefetcher
->nextPrefetchReadyTime(),
1639 if (next_pf_time
!= MaxTick
)
1640 schedMemSideSendEvent(next_pf_time
);
1644 // if we used temp block, check to see if its valid and then clear it out
1645 if (blk
== tempBlock
&& tempBlock
->isValid()) {
1646 PacketPtr wb_pkt
= tempBlock
->isDirty() || writebackClean
?
1647 writebackBlk(blk
) : cleanEvictBlk(blk
);
1648 writebacks
.push_back(wb_pkt
);
1649 invalidateBlock(tempBlock
);
1652 const Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
1653 // copy writebacks to write buffer
1654 doWritebacks(writebacks
, forward_time
);
1656 DPRINTF(CacheVerbose
, "%s: Leaving with %s\n", __func__
, pkt
->print());
1661 Cache::writebackBlk(CacheBlk
*blk
)
1663 chatty_assert(!isReadOnly
|| writebackClean
,
1664 "Writeback from read-only cache");
1665 assert(blk
&& blk
->isValid() && (blk
->isDirty() || writebackClean
));
1667 writebacks
[Request::wbMasterId
]++;
1669 Request
*req
= new Request(tags
->regenerateBlkAddr(blk
), blkSize
, 0,
1670 Request::wbMasterId
);
1671 if (blk
->isSecure())
1672 req
->setFlags(Request::SECURE
);
1674 req
->taskId(blk
->task_id
);
1677 new Packet(req
, blk
->isDirty() ?
1678 MemCmd::WritebackDirty
: MemCmd::WritebackClean
);
1680 DPRINTF(Cache
, "Create Writeback %s writable: %d, dirty: %d\n",
1681 pkt
->print(), blk
->isWritable(), blk
->isDirty());
1683 if (blk
->isWritable()) {
1684 // not asserting shared means we pass the block in modified
1685 // state, mark our own block non-writeable
1686 blk
->status
&= ~BlkWritable
;
1688 // we are in the Owned state, tell the receiver
1689 pkt
->setHasSharers();
1692 // make sure the block is not marked dirty
1693 blk
->status
&= ~BlkDirty
;
1696 pkt
->setDataFromBlock(blk
->data
, blkSize
);
1702 Cache::writecleanBlk(CacheBlk
*blk
, Request::Flags dest
, PacketId id
)
1704 Request
*req
= new Request(tags
->regenerateBlkAddr(blk
), blkSize
, 0,
1705 Request::wbMasterId
);
1706 if (blk
->isSecure()) {
1707 req
->setFlags(Request::SECURE
);
1709 req
->taskId(blk
->task_id
);
1711 PacketPtr pkt
= new Packet(req
, MemCmd::WriteClean
, blkSize
, id
);
1714 req
->setFlags(dest
);
1715 pkt
->setWriteThrough();
1718 DPRINTF(Cache
, "Create %s writable: %d, dirty: %d\n", pkt
->print(),
1719 blk
->isWritable(), blk
->isDirty());
1721 if (blk
->isWritable()) {
1722 // not asserting shared means we pass the block in modified
1723 // state, mark our own block non-writeable
1724 blk
->status
&= ~BlkWritable
;
1726 // we are in the Owned state, tell the receiver
1727 pkt
->setHasSharers();
1730 // make sure the block is not marked dirty
1731 blk
->status
&= ~BlkDirty
;
1734 pkt
->setDataFromBlock(blk
->data
, blkSize
);
1741 Cache::cleanEvictBlk(CacheBlk
*blk
)
1743 assert(!writebackClean
);
1744 assert(blk
&& blk
->isValid() && !blk
->isDirty());
1745 // Creating a zero sized write, a message to the snoop filter
1747 new Request(tags
->regenerateBlkAddr(blk
), blkSize
, 0,
1748 Request::wbMasterId
);
1749 if (blk
->isSecure())
1750 req
->setFlags(Request::SECURE
);
1752 req
->taskId(blk
->task_id
);
1754 PacketPtr pkt
= new Packet(req
, MemCmd::CleanEvict
);
1756 DPRINTF(Cache
, "Create CleanEvict %s\n", pkt
->print());
1762 Cache::memWriteback()
1764 CacheBlkVisitorWrapper
visitor(*this, &Cache::writebackVisitor
);
1765 tags
->forEachBlk(visitor
);
1769 Cache::memInvalidate()
1771 CacheBlkVisitorWrapper
visitor(*this, &Cache::invalidateVisitor
);
1772 tags
->forEachBlk(visitor
);
1776 Cache::isDirty() const
1778 CacheBlkIsDirtyVisitor visitor
;
1779 tags
->forEachBlk(visitor
);
1781 return visitor
.isDirty();
1785 Cache::writebackVisitor(CacheBlk
&blk
)
1787 if (blk
.isDirty()) {
1788 assert(blk
.isValid());
1790 Request
request(tags
->regenerateBlkAddr(&blk
), blkSize
, 0,
1791 Request::funcMasterId
);
1792 request
.taskId(blk
.task_id
);
1793 if (blk
.isSecure()) {
1794 request
.setFlags(Request::SECURE
);
1797 Packet
packet(&request
, MemCmd::WriteReq
);
1798 packet
.dataStatic(blk
.data
);
1800 memSidePort
->sendFunctional(&packet
);
1802 blk
.status
&= ~BlkDirty
;
1809 Cache::invalidateVisitor(CacheBlk
&blk
)
1813 warn_once("Invalidating dirty cache lines. Expect things to break.\n");
1815 if (blk
.isValid()) {
1816 assert(!blk
.isDirty());
1817 invalidateBlock(&blk
);
1824 Cache::allocateBlock(Addr addr
, bool is_secure
, PacketList
&writebacks
)
1826 // Find replacement victim
1827 CacheBlk
*blk
= tags
->findVictim(addr
);
1829 // It is valid to return nullptr if there is no victim
1833 if (blk
->isValid()) {
1834 Addr repl_addr
= tags
->regenerateBlkAddr(blk
);
1835 MSHR
*repl_mshr
= mshrQueue
.findMatch(repl_addr
, blk
->isSecure());
1837 // must be an outstanding upgrade or clean request
1838 // on a block we're about to replace...
1839 assert((!blk
->isWritable() && repl_mshr
->needsWritable()) ||
1840 repl_mshr
->isCleaning());
1841 // too hard to replace block with transient state
1842 // allocation failed, block not inserted
1845 DPRINTF(Cache
, "replacement: replacing %#llx (%s) with %#llx "
1846 "(%s): %s\n", repl_addr
, blk
->isSecure() ? "s" : "ns",
1847 addr
, is_secure
? "s" : "ns",
1848 blk
->isDirty() ? "writeback" : "clean");
1850 if (blk
->wasPrefetched()) {
1853 // Will send up Writeback/CleanEvict snoops via isCachedAbove
1854 // when pushing this writeback list into the write buffer.
1855 if (blk
->isDirty() || writebackClean
) {
1856 // Save writeback packet for handling by caller
1857 writebacks
.push_back(writebackBlk(blk
));
1859 writebacks
.push_back(cleanEvictBlk(blk
));
1861 invalidateBlock(blk
);
1870 Cache::invalidateBlock(CacheBlk
*blk
)
1872 if (blk
!= tempBlock
)
1873 tags
->invalidate(blk
);
1877 // Note that the reason we return a list of writebacks rather than
1878 // inserting them directly in the write buffer is that this function
1879 // is called by both atomic and timing-mode accesses, and in atomic
1880 // mode we don't mess with the write buffer (we just perform the
1881 // writebacks atomically once the original request is complete).
1883 Cache::handleFill(PacketPtr pkt
, CacheBlk
*blk
, PacketList
&writebacks
,
1886 assert(pkt
->isResponse() || pkt
->cmd
== MemCmd::WriteLineReq
);
1887 Addr addr
= pkt
->getAddr();
1888 bool is_secure
= pkt
->isSecure();
1890 CacheBlk::State old_state
= blk
? blk
->status
: 0;
1893 // When handling a fill, we should have no writes to this line.
1894 assert(addr
== pkt
->getBlockAddr(blkSize
));
1895 assert(!writeBuffer
.findMatch(addr
, is_secure
));
1897 if (blk
== nullptr) {
1898 // better have read new data...
1899 assert(pkt
->hasData());
1901 // only read responses and write-line requests have data;
1902 // note that we don't write the data here for write-line - that
1903 // happens in the subsequent call to satisfyRequest
1904 assert(pkt
->isRead() || pkt
->cmd
== MemCmd::WriteLineReq
);
1906 // need to do a replacement if allocating, otherwise we stick
1907 // with the temporary storage
1908 blk
= allocate
? allocateBlock(addr
, is_secure
, writebacks
) : nullptr;
1910 if (blk
== nullptr) {
1911 // No replaceable block or a mostly exclusive
1912 // cache... just use temporary storage to complete the
1913 // current request and then get rid of it
1914 assert(!tempBlock
->isValid());
1916 tempBlock
->set
= tags
->extractSet(addr
);
1917 tempBlock
->tag
= tags
->extractTag(addr
);
1919 tempBlock
->status
|= BlkSecure
;
1921 DPRINTF(Cache
, "using temp block for %#llx (%s)\n", addr
,
1922 is_secure
? "s" : "ns");
1924 tags
->insertBlock(pkt
, blk
);
1927 // we should never be overwriting a valid block
1928 assert(!blk
->isValid());
1930 // existing block... probably an upgrade
1931 assert(blk
->tag
== tags
->extractTag(addr
));
1932 // either we're getting new data or the block should already be valid
1933 assert(pkt
->hasData() || blk
->isValid());
1934 // don't clear block status... if block is already dirty we
1935 // don't want to lose that
1939 blk
->status
|= BlkSecure
;
1940 blk
->status
|= BlkValid
| BlkReadable
;
1942 // sanity check for whole-line writes, which should always be
1943 // marked as writable as part of the fill, and then later marked
1944 // dirty as part of satisfyRequest
1945 if (pkt
->cmd
== MemCmd::WriteLineReq
) {
1946 assert(!pkt
->hasSharers());
1949 // here we deal with setting the appropriate state of the line,
1950 // and we start by looking at the hasSharers flag, and ignore the
1951 // cacheResponding flag (normally signalling dirty data) if the
1952 // packet has sharers, thus the line is never allocated as Owned
1953 // (dirty but not writable), and always ends up being either
1954 // Shared, Exclusive or Modified, see Packet::setCacheResponding
1956 if (!pkt
->hasSharers()) {
1957 // we could get a writable line from memory (rather than a
1958 // cache) even in a read-only cache, note that we set this bit
1959 // even for a read-only cache, possibly revisit this decision
1960 blk
->status
|= BlkWritable
;
1962 // check if we got this via cache-to-cache transfer (i.e., from a
1963 // cache that had the block in Modified or Owned state)
1964 if (pkt
->cacheResponding()) {
1965 // we got the block in Modified state, and invalidated the
1967 blk
->status
|= BlkDirty
;
1969 chatty_assert(!isReadOnly
, "Should never see dirty snoop response "
1970 "in read-only cache %s\n", name());
1974 DPRINTF(Cache
, "Block addr %#llx (%s) moving from state %x to %s\n",
1975 addr
, is_secure
? "s" : "ns", old_state
, blk
->print());
1977 // if we got new data, copy it in (checking for a read response
1978 // and a response that has data is the same in the end)
1979 if (pkt
->isRead()) {
1981 assert(pkt
->hasData());
1982 assert(pkt
->getSize() == blkSize
);
1984 pkt
->writeDataToBlock(blk
->data
, blkSize
);
1986 // We pay for fillLatency here.
1987 blk
->whenReady
= clockEdge() + fillLatency
* clockPeriod() +
1994 /////////////////////////////////////////////////////
1996 // Snoop path: requests coming in from the memory side
1998 /////////////////////////////////////////////////////
2001 Cache::doTimingSupplyResponse(PacketPtr req_pkt
, const uint8_t *blk_data
,
2002 bool already_copied
, bool pending_inval
)
2005 assert(req_pkt
->isRequest());
2006 assert(req_pkt
->needsResponse());
2008 DPRINTF(Cache
, "%s: for %s\n", __func__
, req_pkt
->print());
2009 // timing-mode snoop responses require a new packet, unless we
2010 // already made a copy...
2011 PacketPtr pkt
= req_pkt
;
2012 if (!already_copied
)
2013 // do not clear flags, and allocate space for data if the
2014 // packet needs it (the only packets that carry data are read
2016 pkt
= new Packet(req_pkt
, false, req_pkt
->isRead());
2018 assert(req_pkt
->req
->isUncacheable() || req_pkt
->isInvalidate() ||
2020 pkt
->makeTimingResponse();
2021 if (pkt
->isRead()) {
2022 pkt
->setDataFromBlock(blk_data
, blkSize
);
2024 if (pkt
->cmd
== MemCmd::ReadResp
&& pending_inval
) {
2025 // Assume we defer a response to a read from a far-away cache
2026 // A, then later defer a ReadExcl from a cache B on the same
2027 // bus as us. We'll assert cacheResponding in both cases, but
2028 // in the latter case cacheResponding will keep the
2029 // invalidation from reaching cache A. This special response
2030 // tells cache A that it gets the block to satisfy its read,
2031 // but must immediately invalidate it.
2032 pkt
->cmd
= MemCmd::ReadRespWithInvalidate
;
2034 // Here we consider forward_time, paying for just forward latency and
2035 // also charging the delay provided by the xbar.
2036 // forward_time is used as send_time in next allocateWriteBuffer().
2037 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
2038 // Here we reset the timing of the packet.
2039 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
2040 DPRINTF(CacheVerbose
, "%s: created response: %s tick: %lu\n", __func__
,
2041 pkt
->print(), forward_time
);
2042 memSidePort
->schedTimingSnoopResp(pkt
, forward_time
, true);
2046 Cache::handleSnoop(PacketPtr pkt
, CacheBlk
*blk
, bool is_timing
,
2047 bool is_deferred
, bool pending_inval
)
2049 DPRINTF(CacheVerbose
, "%s: for %s\n", __func__
, pkt
->print());
2050 // deferred snoops can only happen in timing mode
2051 assert(!(is_deferred
&& !is_timing
));
2052 // pending_inval only makes sense on deferred snoops
2053 assert(!(pending_inval
&& !is_deferred
));
2054 assert(pkt
->isRequest());
2056 // the packet may get modified if we or a forwarded snooper
2057 // responds in atomic mode, so remember a few things about the
2058 // original packet up front
2059 bool invalidate
= pkt
->isInvalidate();
2060 bool M5_VAR_USED needs_writable
= pkt
->needsWritable();
2062 // at the moment we could get an uncacheable write which does not
2063 // have the invalidate flag, and we need a suitable way of dealing
2065 panic_if(invalidate
&& pkt
->req
->isUncacheable(),
2066 "%s got an invalidating uncacheable snoop request %s",
2067 name(), pkt
->print());
2069 uint32_t snoop_delay
= 0;
2071 if (forwardSnoops
) {
2072 // first propagate snoop upward to see if anyone above us wants to
2073 // handle it. save & restore packet src since it will get
2074 // rewritten to be relative to cpu-side bus (if any)
2075 bool alreadyResponded
= pkt
->cacheResponding();
2077 // copy the packet so that we can clear any flags before
2078 // forwarding it upwards, we also allocate data (passing
2079 // the pointer along in case of static data), in case
2080 // there is a snoop hit in upper levels
2081 Packet
snoopPkt(pkt
, true, true);
2082 snoopPkt
.setExpressSnoop();
2083 // the snoop packet does not need to wait any additional
2085 snoopPkt
.headerDelay
= snoopPkt
.payloadDelay
= 0;
2086 cpuSidePort
->sendTimingSnoopReq(&snoopPkt
);
2088 // add the header delay (including crossbar and snoop
2089 // delays) of the upward snoop to the snoop delay for this
2091 snoop_delay
+= snoopPkt
.headerDelay
;
2093 if (snoopPkt
.cacheResponding()) {
2094 // cache-to-cache response from some upper cache
2095 assert(!alreadyResponded
);
2096 pkt
->setCacheResponding();
2098 // upstream cache has the block, or has an outstanding
2099 // MSHR, pass the flag on
2100 if (snoopPkt
.hasSharers()) {
2101 pkt
->setHasSharers();
2103 // If this request is a prefetch or clean evict and an upper level
2104 // signals block present, make sure to propagate the block
2105 // presence to the requester.
2106 if (snoopPkt
.isBlockCached()) {
2107 pkt
->setBlockCached();
2109 // If the request was satisfied by snooping the cache
2110 // above, mark the original packet as satisfied too.
2111 if (snoopPkt
.satisfied()) {
2112 pkt
->setSatisfied();
2115 cpuSidePort
->sendAtomicSnoop(pkt
);
2116 if (!alreadyResponded
&& pkt
->cacheResponding()) {
2117 // cache-to-cache response from some upper cache:
2118 // forward response to original requester
2119 assert(pkt
->isResponse());
2124 bool respond
= false;
2125 bool blk_valid
= blk
&& blk
->isValid();
2126 if (pkt
->isClean()) {
2127 if (blk_valid
&& blk
->isDirty()) {
2128 DPRINTF(CacheVerbose
, "%s: packet (snoop) %s found block: %s\n",
2129 __func__
, pkt
->print(), blk
->print());
2130 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest(), pkt
->id
);
2131 PacketList writebacks
;
2132 writebacks
.push_back(wb_pkt
);
2135 // anything that is merely forwarded pays for the forward
2136 // latency and the delay provided by the crossbar
2137 Tick forward_time
= clockEdge(forwardLatency
) +
2139 doWritebacks(writebacks
, forward_time
);
2141 doWritebacksAtomic(writebacks
);
2143 pkt
->setSatisfied();
2145 } else if (!blk_valid
) {
2146 DPRINTF(CacheVerbose
, "%s: snoop miss for %s\n", __func__
,
2149 // we no longer have the block, and will not respond, but a
2150 // packet was allocated in MSHR::handleSnoop and we have
2152 assert(pkt
->needsResponse());
2154 // we have passed the block to a cache upstream, that
2155 // cache should be responding
2156 assert(pkt
->cacheResponding());
2162 DPRINTF(Cache
, "%s: snoop hit for %s, old state is %s\n", __func__
,
2163 pkt
->print(), blk
->print());
2165 // We may end up modifying both the block state and the packet (if
2166 // we respond in atomic mode), so just figure out what to do now
2167 // and then do it later. We respond to all snoops that need
2168 // responses provided we have the block in dirty state. The
2169 // invalidation itself is taken care of below. We don't respond to
2170 // cache maintenance operations as this is done by the destination
2172 respond
= blk
->isDirty() && pkt
->needsResponse();
2174 chatty_assert(!(isReadOnly
&& blk
->isDirty()), "Should never have "
2175 "a dirty block in a read-only cache %s\n", name());
2178 // Invalidate any prefetch's from below that would strip write permissions
2179 // MemCmd::HardPFReq is only observed by upstream caches. After missing
2180 // above and in it's own cache, a new MemCmd::ReadReq is created that
2181 // downstream caches observe.
2182 if (pkt
->mustCheckAbove()) {
2183 DPRINTF(Cache
, "Found addr %#llx in upper level cache for snoop %s "
2184 "from lower cache\n", pkt
->getAddr(), pkt
->print());
2185 pkt
->setBlockCached();
2189 if (pkt
->isRead() && !invalidate
) {
2190 // reading without requiring the line in a writable state
2191 assert(!needs_writable
);
2192 pkt
->setHasSharers();
2194 // if the requesting packet is uncacheable, retain the line in
2195 // the current state, otherwhise unset the writable flag,
2196 // which means we go from Modified to Owned (and will respond
2197 // below), remain in Owned (and will respond below), from
2198 // Exclusive to Shared, or remain in Shared
2199 if (!pkt
->req
->isUncacheable())
2200 blk
->status
&= ~BlkWritable
;
2201 DPRINTF(Cache
, "new state is %s\n", blk
->print());
2205 // prevent anyone else from responding, cache as well as
2206 // memory, and also prevent any memory from even seeing the
2208 pkt
->setCacheResponding();
2209 if (!pkt
->isClean() && blk
->isWritable()) {
2210 // inform the cache hierarchy that this cache had the line
2211 // in the Modified state so that we avoid unnecessary
2212 // invalidations (see Packet::setResponderHadWritable)
2213 pkt
->setResponderHadWritable();
2215 // in the case of an uncacheable request there is no point
2216 // in setting the responderHadWritable flag, but since the
2217 // recipient does not care there is no harm in doing so
2219 // if the packet has needsWritable set we invalidate our
2220 // copy below and all other copies will be invalidates
2221 // through express snoops, and if needsWritable is not set
2222 // we already called setHasSharers above
2225 // if we are returning a writable and dirty (Modified) line,
2226 // we should be invalidating the line
2227 panic_if(!invalidate
&& !pkt
->hasSharers(),
2228 "%s is passing a Modified line through %s, "
2229 "but keeping the block", name(), pkt
->print());
2232 doTimingSupplyResponse(pkt
, blk
->data
, is_deferred
, pending_inval
);
2234 pkt
->makeAtomicResponse();
2235 // packets such as upgrades do not actually have any data
2238 pkt
->setDataFromBlock(blk
->data
, blkSize
);
2242 if (!respond
&& is_deferred
) {
2243 assert(pkt
->needsResponse());
2245 // if we copied the deferred packet with the intention to
2246 // respond, but are not responding, then a cache above us must
2247 // be, and we can use this as the indication of whether this
2248 // is a packet where we created a copy of the request or not
2249 if (!pkt
->cacheResponding()) {
2256 // Do this last in case it deallocates block data or something
2258 if (blk_valid
&& invalidate
) {
2259 invalidateBlock(blk
);
2260 DPRINTF(Cache
, "new state is %s\n", blk
->print());
2268 Cache::recvTimingSnoopReq(PacketPtr pkt
)
2270 DPRINTF(CacheVerbose
, "%s: for %s\n", __func__
, pkt
->print());
2272 // Snoops shouldn't happen when bypassing caches
2273 assert(!system
->bypassCaches());
2275 // no need to snoop requests that are not in range
2276 if (!inRange(pkt
->getAddr())) {
2280 bool is_secure
= pkt
->isSecure();
2281 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), is_secure
);
2283 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
2284 MSHR
*mshr
= mshrQueue
.findMatch(blk_addr
, is_secure
);
2286 // Update the latency cost of the snoop so that the crossbar can
2287 // account for it. Do not overwrite what other neighbouring caches
2288 // have already done, rather take the maximum. The update is
2289 // tentative, for cases where we return before an upward snoop
2291 pkt
->snoopDelay
= std::max
<uint32_t>(pkt
->snoopDelay
,
2292 lookupLatency
* clockPeriod());
2294 // Inform request(Prefetch, CleanEvict or Writeback) from below of
2295 // MSHR hit, set setBlockCached.
2296 if (mshr
&& pkt
->mustCheckAbove()) {
2297 DPRINTF(Cache
, "Setting block cached for %s from lower cache on "
2298 "mshr hit\n", pkt
->print());
2299 pkt
->setBlockCached();
2303 // Bypass any existing cache maintenance requests if the request
2304 // has been satisfied already (i.e., the dirty block has been
2306 if (mshr
&& pkt
->req
->isCacheMaintenance() && pkt
->satisfied()) {
2310 // Let the MSHR itself track the snoop and decide whether we want
2311 // to go ahead and do the regular cache snoop
2312 if (mshr
&& mshr
->handleSnoop(pkt
, order
++)) {
2313 DPRINTF(Cache
, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
2314 "mshrs: %s\n", blk_addr
, is_secure
? "s" : "ns",
2317 if (mshr
->getNumTargets() > numTarget
)
2318 warn("allocating bonus target for snoop"); //handle later
2322 //We also need to check the writeback buffers and handle those
2323 WriteQueueEntry
*wb_entry
= writeBuffer
.findMatch(blk_addr
, is_secure
);
2325 DPRINTF(Cache
, "Snoop hit in writeback to addr %#llx (%s)\n",
2326 pkt
->getAddr(), is_secure
? "s" : "ns");
2327 // Expect to see only Writebacks and/or CleanEvicts here, both of
2328 // which should not be generated for uncacheable data.
2329 assert(!wb_entry
->isUncacheable());
2330 // There should only be a single request responsible for generating
2331 // Writebacks/CleanEvicts.
2332 assert(wb_entry
->getNumTargets() == 1);
2333 PacketPtr wb_pkt
= wb_entry
->getTarget()->pkt
;
2334 assert(wb_pkt
->isEviction() || wb_pkt
->cmd
== MemCmd::WriteClean
);
2336 if (pkt
->isEviction()) {
2337 // if the block is found in the write queue, set the BLOCK_CACHED
2338 // flag for Writeback/CleanEvict snoop. On return the snoop will
2339 // propagate the BLOCK_CACHED flag in Writeback packets and prevent
2340 // any CleanEvicts from travelling down the memory hierarchy.
2341 pkt
->setBlockCached();
2342 DPRINTF(Cache
, "%s: Squashing %s from lower cache on writequeue "
2343 "hit\n", __func__
, pkt
->print());
2347 // conceptually writebacks are no different to other blocks in
2348 // this cache, so the behaviour is modelled after handleSnoop,
2349 // the difference being that instead of querying the block
2350 // state to determine if it is dirty and writable, we use the
2351 // command and fields of the writeback packet
2352 bool respond
= wb_pkt
->cmd
== MemCmd::WritebackDirty
&&
2353 pkt
->needsResponse();
2354 bool have_writable
= !wb_pkt
->hasSharers();
2355 bool invalidate
= pkt
->isInvalidate();
2357 if (!pkt
->req
->isUncacheable() && pkt
->isRead() && !invalidate
) {
2358 assert(!pkt
->needsWritable());
2359 pkt
->setHasSharers();
2360 wb_pkt
->setHasSharers();
2364 pkt
->setCacheResponding();
2366 if (have_writable
) {
2367 pkt
->setResponderHadWritable();
2370 doTimingSupplyResponse(pkt
, wb_pkt
->getConstPtr
<uint8_t>(),
2374 if (invalidate
&& wb_pkt
->cmd
!= MemCmd::WriteClean
) {
2375 // Invalidation trumps our writeback... discard here
2376 // Note: markInService will remove entry from writeback buffer.
2377 markInService(wb_entry
);
2382 // If this was a shared writeback, there may still be
2383 // other shared copies above that require invalidation.
2384 // We could be more selective and return here if the
2385 // request is non-exclusive or if the writeback is
2387 uint32_t snoop_delay
= handleSnoop(pkt
, blk
, true, false, false);
2389 // Override what we did when we first saw the snoop, as we now
2390 // also have the cost of the upwards snoops to account for
2391 pkt
->snoopDelay
= std::max
<uint32_t>(pkt
->snoopDelay
, snoop_delay
+
2392 lookupLatency
* clockPeriod());
2396 Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt
)
2398 // Express snoop responses from master to slave, e.g., from L1 to L2
2399 cache
->recvTimingSnoopResp(pkt
);
2404 Cache::recvAtomicSnoop(PacketPtr pkt
)
2406 // Snoops shouldn't happen when bypassing caches
2407 assert(!system
->bypassCaches());
2409 // no need to snoop requests that are not in range.
2410 if (!inRange(pkt
->getAddr())) {
2414 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), pkt
->isSecure());
2415 uint32_t snoop_delay
= handleSnoop(pkt
, blk
, false, false, false);
2416 return snoop_delay
+ lookupLatency
* clockPeriod();
2421 Cache::getNextQueueEntry()
2423 // Check both MSHR queue and write buffer for potential requests,
2424 // note that null does not mean there is no request, it could
2425 // simply be that it is not ready
2426 MSHR
*miss_mshr
= mshrQueue
.getNext();
2427 WriteQueueEntry
*wq_entry
= writeBuffer
.getNext();
2429 // If we got a write buffer request ready, first priority is a
2430 // full write buffer, otherwise we favour the miss requests
2431 if (wq_entry
&& (writeBuffer
.isFull() || !miss_mshr
)) {
2432 // need to search MSHR queue for conflicting earlier miss.
2433 MSHR
*conflict_mshr
=
2434 mshrQueue
.findPending(wq_entry
->blkAddr
,
2435 wq_entry
->isSecure
);
2437 if (conflict_mshr
&& conflict_mshr
->order
< wq_entry
->order
) {
2438 // Service misses in order until conflict is cleared.
2439 return conflict_mshr
;
2441 // @todo Note that we ignore the ready time of the conflict here
2444 // No conflicts; issue write
2446 } else if (miss_mshr
) {
2447 // need to check for conflicting earlier writeback
2448 WriteQueueEntry
*conflict_mshr
=
2449 writeBuffer
.findPending(miss_mshr
->blkAddr
,
2450 miss_mshr
->isSecure
);
2451 if (conflict_mshr
) {
2452 // not sure why we don't check order here... it was in the
2453 // original code but commented out.
2455 // The only way this happens is if we are
2456 // doing a write and we didn't have permissions
2457 // then subsequently saw a writeback (owned got evicted)
2458 // We need to make sure to perform the writeback first
2459 // To preserve the dirty data, then we can issue the write
2461 // should we return wq_entry here instead? I.e. do we
2462 // have to flush writes in order? I don't think so... not
2463 // for Alpha anyway. Maybe for x86?
2464 return conflict_mshr
;
2466 // @todo Note that we ignore the ready time of the conflict here
2469 // No conflicts; issue read
2473 // fall through... no pending requests. Try a prefetch.
2474 assert(!miss_mshr
&& !wq_entry
);
2475 if (prefetcher
&& mshrQueue
.canPrefetch()) {
2476 // If we have a miss queue slot, we can try a prefetch
2477 PacketPtr pkt
= prefetcher
->getPacket();
2479 Addr pf_addr
= pkt
->getBlockAddr(blkSize
);
2480 if (!tags
->findBlock(pf_addr
, pkt
->isSecure()) &&
2481 !mshrQueue
.findMatch(pf_addr
, pkt
->isSecure()) &&
2482 !writeBuffer
.findMatch(pf_addr
, pkt
->isSecure())) {
2483 // Update statistic on number of prefetches issued
2484 // (hwpf_mshr_misses)
2485 assert(pkt
->req
->masterId() < system
->maxMasters());
2486 mshr_misses
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
2488 // allocate an MSHR and return it, note
2489 // that we send the packet straight away, so do not
2490 // schedule the send
2491 return allocateMissBuffer(pkt
, curTick(), false);
2493 // free the request and packet
2504 Cache::isCachedAbove(PacketPtr pkt
, bool is_timing
) const
2508 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
2509 // Writeback snoops into upper level caches to check for copies of the
2510 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
2511 // packet, the cache can inform the crossbar below of presence or absence
2514 Packet
snoop_pkt(pkt
, true, false);
2515 snoop_pkt
.setExpressSnoop();
2516 // Assert that packet is either Writeback or CleanEvict and not a
2517 // prefetch request because prefetch requests need an MSHR and may
2518 // generate a snoop response.
2519 assert(pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
);
2520 snoop_pkt
.senderState
= nullptr;
2521 cpuSidePort
->sendTimingSnoopReq(&snoop_pkt
);
2522 // Writeback/CleanEvict snoops do not generate a snoop response.
2523 assert(!(snoop_pkt
.cacheResponding()));
2524 return snoop_pkt
.isBlockCached();
2526 cpuSidePort
->sendAtomicSnoop(pkt
);
2527 return pkt
->isBlockCached();
2532 Cache::nextQueueReadyTime() const
2534 Tick nextReady
= std::min(mshrQueue
.nextReadyTime(),
2535 writeBuffer
.nextReadyTime());
2537 // Don't signal prefetch ready time if no MSHRs available
2538 // Will signal once enoguh MSHRs are deallocated
2539 if (prefetcher
&& mshrQueue
.canPrefetch()) {
2540 nextReady
= std::min(nextReady
,
2541 prefetcher
->nextPrefetchReadyTime());
2548 Cache::sendMSHRQueuePacket(MSHR
* mshr
)
2552 // use request from 1st target
2553 PacketPtr tgt_pkt
= mshr
->getTarget()->pkt
;
2555 DPRINTF(Cache
, "%s: MSHR %s\n", __func__
, tgt_pkt
->print());
2557 CacheBlk
*blk
= tags
->findBlock(mshr
->blkAddr
, mshr
->isSecure
);
2559 if (tgt_pkt
->cmd
== MemCmd::HardPFReq
&& forwardSnoops
) {
2560 // we should never have hardware prefetches to allocated
2562 assert(blk
== nullptr);
2564 // We need to check the caches above us to verify that
2565 // they don't have a copy of this block in the dirty state
2566 // at the moment. Without this check we could get a stale
2567 // copy from memory that might get used in place of the
2569 Packet
snoop_pkt(tgt_pkt
, true, false);
2570 snoop_pkt
.setExpressSnoop();
2571 // We are sending this packet upwards, but if it hits we will
2572 // get a snoop response that we end up treating just like a
2573 // normal response, hence it needs the MSHR as its sender
2575 snoop_pkt
.senderState
= mshr
;
2576 cpuSidePort
->sendTimingSnoopReq(&snoop_pkt
);
2578 // Check to see if the prefetch was squashed by an upper cache (to
2579 // prevent us from grabbing the line) or if a Check to see if a
2580 // writeback arrived between the time the prefetch was placed in
2581 // the MSHRs and when it was selected to be sent or if the
2582 // prefetch was squashed by an upper cache.
2584 // It is important to check cacheResponding before
2585 // prefetchSquashed. If another cache has committed to
2586 // responding, it will be sending a dirty response which will
2587 // arrive at the MSHR allocated for this request. Checking the
2588 // prefetchSquash first may result in the MSHR being
2589 // prematurely deallocated.
2590 if (snoop_pkt
.cacheResponding()) {
2591 auto M5_VAR_USED r
= outstandingSnoop
.insert(snoop_pkt
.req
);
2594 // if we are getting a snoop response with no sharers it
2595 // will be allocated as Modified
2596 bool pending_modified_resp
= !snoop_pkt
.hasSharers();
2597 markInService(mshr
, pending_modified_resp
);
2599 DPRINTF(Cache
, "Upward snoop of prefetch for addr"
2601 tgt_pkt
->getAddr(), tgt_pkt
->isSecure()? "s": "ns");
2605 if (snoop_pkt
.isBlockCached()) {
2606 DPRINTF(Cache
, "Block present, prefetch squashed by cache. "
2607 "Deallocating mshr target %#x.\n",
2610 // Deallocate the mshr target
2611 if (mshrQueue
.forceDeallocateTarget(mshr
)) {
2612 // Clear block if this deallocation resulted freed an
2613 // mshr when all had previously been utilized
2614 clearBlocked(Blocked_NoMSHRs
);
2617 // given that no response is expected, delete Request and Packet
2618 delete tgt_pkt
->req
;
2625 // either a prefetch that is not present upstream, or a normal
2626 // MSHR request, proceed to get the packet to send downstream
2627 PacketPtr pkt
= createMissPacket(tgt_pkt
, blk
, mshr
->needsWritable());
2629 mshr
->isForward
= (pkt
== nullptr);
2631 if (mshr
->isForward
) {
2632 // not a cache block request, but a response is expected
2633 // make copy of current packet to forward, keep current
2634 // copy for response handling
2635 pkt
= new Packet(tgt_pkt
, false, true);
2636 assert(!pkt
->isWrite());
2639 // play it safe and append (rather than set) the sender state,
2640 // as forwarded packets may already have existing state
2641 pkt
->pushSenderState(mshr
);
2643 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
2644 // A cache clean opearation is looking for a dirty block. Mark
2645 // the packet so that the destination xbar can determine that
2646 // there will be a follow-up write packet as well.
2647 pkt
->setSatisfied();
2650 if (!memSidePort
->sendTimingReq(pkt
)) {
2651 // we are awaiting a retry, but we
2652 // delete the packet and will be creating a new packet
2653 // when we get the opportunity
2656 // note that we have now masked any requestBus and
2657 // schedSendEvent (we will wait for a retry before
2658 // doing anything), and this is so even if we do not
2659 // care about this packet and might override it before
2663 // As part of the call to sendTimingReq the packet is
2664 // forwarded to all neighbouring caches (and any caches
2665 // above them) as a snoop. Thus at this point we know if
2666 // any of the neighbouring caches are responding, and if
2667 // so, we know it is dirty, and we can determine if it is
2668 // being passed as Modified, making our MSHR the ordering
2670 bool pending_modified_resp
= !pkt
->hasSharers() &&
2671 pkt
->cacheResponding();
2672 markInService(mshr
, pending_modified_resp
);
2673 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
2674 // A cache clean opearation is looking for a dirty
2675 // block. If a dirty block is encountered a WriteClean
2676 // will update any copies to the path to the memory
2677 // until the point of reference.
2678 DPRINTF(CacheVerbose
, "%s: packet %s found block: %s\n",
2679 __func__
, pkt
->print(), blk
->print());
2680 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest(),
2682 PacketList writebacks
;
2683 writebacks
.push_back(wb_pkt
);
2684 doWritebacks(writebacks
, 0);
2692 Cache::sendWriteQueuePacket(WriteQueueEntry
* wq_entry
)
2696 // always a single target for write queue entries
2697 PacketPtr tgt_pkt
= wq_entry
->getTarget()->pkt
;
2699 DPRINTF(Cache
, "%s: write %s\n", __func__
, tgt_pkt
->print());
2701 // forward as is, both for evictions and uncacheable writes
2702 if (!memSidePort
->sendTimingReq(tgt_pkt
)) {
2703 // note that we have now masked any requestBus and
2704 // schedSendEvent (we will wait for a retry before
2705 // doing anything), and this is so even if we do not
2706 // care about this packet and might override it before
2710 markInService(wq_entry
);
2716 Cache::serialize(CheckpointOut
&cp
) const
2718 bool dirty(isDirty());
2721 warn("*** The cache still contains dirty data. ***\n");
2722 warn(" Make sure to drain the system using the correct flags.\n");
2723 warn(" This checkpoint will not restore correctly and dirty data "
2724 " in the cache will be lost!\n");
2727 // Since we don't checkpoint the data in the cache, any dirty data
2728 // will be lost when restoring from a checkpoint of a system that
2729 // wasn't drained properly. Flag the checkpoint as invalid if the
2730 // cache contains dirty data.
2731 bool bad_checkpoint(dirty
);
2732 SERIALIZE_SCALAR(bad_checkpoint
);
2736 Cache::unserialize(CheckpointIn
&cp
)
2738 bool bad_checkpoint
;
2739 UNSERIALIZE_SCALAR(bad_checkpoint
);
2740 if (bad_checkpoint
) {
2741 fatal("Restoring from checkpoints with dirty caches is not supported "
2742 "in the classic memory system. Please remove any caches or "
2743 " drain them properly before taking checkpoints.\n");
2754 Cache::CpuSidePort::getAddrRanges() const
2756 return cache
->getAddrRanges();
2760 Cache::CpuSidePort::tryTiming(PacketPtr pkt
)
2762 assert(!cache
->system
->bypassCaches());
2764 // always let express snoop packets through if even if blocked
2765 if (pkt
->isExpressSnoop()) {
2767 } else if (isBlocked() || mustSendRetry
) {
2768 // either already committed to send a retry, or blocked
2769 mustSendRetry
= true;
2772 mustSendRetry
= false;
2777 Cache::CpuSidePort::recvTimingReq(PacketPtr pkt
)
2779 assert(!cache
->system
->bypassCaches());
2781 // always let express snoop packets through if even if blocked
2782 if (pkt
->isExpressSnoop() || tryTiming(pkt
)) {
2783 cache
->recvTimingReq(pkt
);
2790 Cache::CpuSidePort::recvAtomic(PacketPtr pkt
)
2792 return cache
->recvAtomic(pkt
);
2796 Cache::CpuSidePort::recvFunctional(PacketPtr pkt
)
2798 // functional request
2799 cache
->functionalAccess(pkt
, true);
2803 CpuSidePort::CpuSidePort(const std::string
&_name
, Cache
*_cache
,
2804 const std::string
&_label
)
2805 : BaseCache::CacheSlavePort(_name
, _cache
, _label
), cache(_cache
)
2810 CacheParams::create()
2813 assert(replacement_policy
);
2815 return new Cache(this);
2824 Cache::MemSidePort::recvTimingResp(PacketPtr pkt
)
2826 cache
->recvTimingResp(pkt
);
2830 // Express snooping requests to memside port
2832 Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt
)
2834 // handle snooping requests
2835 cache
->recvTimingSnoopReq(pkt
);
2839 Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt
)
2841 return cache
->recvAtomicSnoop(pkt
);
2845 Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt
)
2847 // functional snoop (note that in contrast to atomic we don't have
2848 // a specific functionalSnoop method, as they have the same
2849 // behaviour regardless)
2850 cache
->functionalAccess(pkt
, false);
2854 Cache::CacheReqPacketQueue::sendDeferredPacket()
2857 assert(!waitingOnRetry
);
2859 // there should never be any deferred request packets in the
2860 // queue, instead we resly on the cache to provide the packets
2861 // from the MSHR queue or write queue
2862 assert(deferredPacketReadyTime() == MaxTick
);
2864 // check for request packets (requests & writebacks)
2865 QueueEntry
* entry
= cache
.getNextQueueEntry();
2868 // can happen if e.g. we attempt a writeback and fail, but
2869 // before the retry, the writeback is eliminated because
2870 // we snoop another cache's ReadEx.
2872 // let our snoop responses go first if there are responses to
2873 // the same addresses
2874 if (checkConflictingSnoop(entry
->blkAddr
)) {
2877 waitingOnRetry
= entry
->sendPacket(cache
);
2880 // if we succeeded and are not waiting for a retry, schedule the
2881 // next send considering when the next queue is ready, note that
2882 // snoop responses have their own packet queue and thus schedule
2884 if (!waitingOnRetry
) {
2885 schedSendEvent(cache
.nextQueueReadyTime());
2890 MemSidePort::MemSidePort(const std::string
&_name
, Cache
*_cache
,
2891 const std::string
&_label
)
2892 : BaseCache::CacheMasterPort(_name
, _cache
, _reqQueue
, _snoopRespQueue
),
2893 _reqQueue(*_cache
, *this, _snoopRespQueue
, _label
),
2894 _snoopRespQueue(*_cache
, *this, _label
), cache(_cache
)