2 * Copyright (c) 2010-2017 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
);
401 if (pkt
->isSecure()) {
402 blk
->status
|= BlkSecure
;
405 // only mark the block dirty if we got a writeback command,
406 // and leave it as is for a clean writeback
407 if (pkt
->cmd
== MemCmd::WritebackDirty
) {
408 blk
->status
|= BlkDirty
;
410 // if the packet does not have sharers, it is passing
411 // writable, and we got the writeback in Modified or Exclusive
412 // state, if not we are in the Owned or Shared state
413 if (!pkt
->hasSharers()) {
414 blk
->status
|= BlkWritable
;
416 // nothing else to do; writeback doesn't expect response
417 assert(!pkt
->needsResponse());
418 std::memcpy(blk
->data
, pkt
->getConstPtr
<uint8_t>(), blkSize
);
419 DPRINTF(Cache
, "%s new state is %s\n", __func__
, blk
->print());
422 } else if (pkt
->cmd
== MemCmd::CleanEvict
) {
423 if (blk
!= nullptr) {
424 // Found the block in the tags, need to stop CleanEvict from
425 // propagating further down the hierarchy. Returning true will
426 // treat the CleanEvict like a satisfied write request and delete
430 // We didn't find the block here, propagate the CleanEvict further
431 // down the memory hierarchy. Returning false will treat the CleanEvict
432 // like a Writeback which could not find a replaceable block so has to
435 } else if (pkt
->cmd
== MemCmd::WriteClean
) {
436 // WriteClean handling is a special case. We can allocate a
437 // block directly if it doesn't exist and we can update the
438 // block immediately. The WriteClean transfers the ownership
439 // of the block as well.
440 assert(blkSize
== pkt
->getSize());
443 if (pkt
->writeThrough()) {
444 // if this is a write through packet, we don't try to
445 // allocate if the block is not present
448 // a writeback that misses needs to allocate a new block
449 blk
= allocateBlock(pkt
->getAddr(), pkt
->isSecure(),
452 // no replaceable block available: give up, fwd to
457 tags
->insertBlock(pkt
, blk
);
459 blk
->status
= (BlkValid
| BlkReadable
);
460 if (pkt
->isSecure()) {
461 blk
->status
|= BlkSecure
;
466 // at this point either this is a writeback or a write-through
467 // write clean operation and the block is already in this
468 // cache, we need to update the data and the block flags
470 if (!pkt
->writeThrough()) {
471 blk
->status
|= BlkDirty
;
473 // nothing else to do; writeback doesn't expect response
474 assert(!pkt
->needsResponse());
475 std::memcpy(blk
->data
, pkt
->getConstPtr
<uint8_t>(), blkSize
);
476 DPRINTF(Cache
, "%s new state is %s\n", __func__
, blk
->print());
479 // populate the time when the block will be ready to access.
480 blk
->whenReady
= clockEdge(fillLatency
) + pkt
->headerDelay
+
482 // if this a write-through packet it will be sent to cache
484 return !pkt
->writeThrough();
485 } else if (blk
&& (pkt
->needsWritable() ? blk
->isWritable() :
486 blk
->isReadable())) {
487 // OK to satisfy access
489 satisfyRequest(pkt
, blk
);
490 maintainClusivity(pkt
->fromCache(), blk
);
495 // Can't satisfy access normally... either no block (blk == nullptr)
496 // or have block but need writable
500 if (blk
== nullptr && pkt
->isLLSC() && pkt
->isWrite()) {
501 // complete miss on store conditional... just give up now
502 pkt
->req
->setExtraData(0);
510 Cache::maintainClusivity(bool from_cache
, CacheBlk
*blk
)
512 if (from_cache
&& blk
&& blk
->isValid() && !blk
->isDirty() &&
513 clusivity
== Enums::mostly_excl
) {
514 // if we have responded to a cache, and our block is still
515 // valid, but not dirty, and this cache is mostly exclusive
516 // with respect to the cache above, drop the block
517 invalidateBlock(blk
);
522 Cache::doWritebacks(PacketList
& writebacks
, Tick forward_time
)
524 while (!writebacks
.empty()) {
525 PacketPtr wbPkt
= writebacks
.front();
526 // We use forwardLatency here because we are copying writebacks to
529 // Call isCachedAbove for Writebacks, CleanEvicts and
530 // WriteCleans to discover if the block is cached above.
531 if (isCachedAbove(wbPkt
)) {
532 if (wbPkt
->cmd
== MemCmd::CleanEvict
) {
533 // Delete CleanEvict because cached copies exist above. The
534 // packet destructor will delete the request object because
535 // this is a non-snoop request packet which does not require a
538 } else if (wbPkt
->cmd
== MemCmd::WritebackClean
) {
539 // clean writeback, do not send since the block is
540 // still cached above
541 assert(writebackClean
);
544 assert(wbPkt
->cmd
== MemCmd::WritebackDirty
||
545 wbPkt
->cmd
== MemCmd::WriteClean
);
546 // Set BLOCK_CACHED flag in Writeback and send below, so that
547 // the Writeback does not reset the bit corresponding to this
548 // address in the snoop filter below.
549 wbPkt
->setBlockCached();
550 allocateWriteBuffer(wbPkt
, forward_time
);
553 // If the block is not cached above, send packet below. Both
554 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
555 // reset the bit corresponding to this address in the snoop filter
557 allocateWriteBuffer(wbPkt
, forward_time
);
559 writebacks
.pop_front();
564 Cache::doWritebacksAtomic(PacketList
& writebacks
)
566 while (!writebacks
.empty()) {
567 PacketPtr wbPkt
= writebacks
.front();
568 // Call isCachedAbove for both Writebacks and CleanEvicts. If
569 // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
570 // and discard CleanEvicts.
571 if (isCachedAbove(wbPkt
, false)) {
572 if (wbPkt
->cmd
== MemCmd::WritebackDirty
||
573 wbPkt
->cmd
== MemCmd::WriteClean
) {
574 // Set BLOCK_CACHED flag in Writeback and send below,
575 // so that the Writeback does not reset the bit
576 // corresponding to this address in the snoop filter
577 // below. We can discard CleanEvicts because cached
578 // copies exist above. Atomic mode isCachedAbove
579 // modifies packet to set BLOCK_CACHED flag
580 memSidePort
->sendAtomic(wbPkt
);
583 // If the block is not cached above, send packet below. Both
584 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
585 // reset the bit corresponding to this address in the snoop filter
587 memSidePort
->sendAtomic(wbPkt
);
589 writebacks
.pop_front();
590 // In case of CleanEvicts, the packet destructor will delete the
591 // request object because this is a non-snoop request packet which
592 // does not require a response.
599 Cache::recvTimingSnoopResp(PacketPtr pkt
)
601 DPRINTF(Cache
, "%s for %s\n", __func__
, pkt
->print());
603 assert(pkt
->isResponse());
604 assert(!system
->bypassCaches());
606 // determine if the response is from a snoop request we created
607 // (in which case it should be in the outstandingSnoop), or if we
608 // merely forwarded someone else's snoop request
609 const bool forwardAsSnoop
= outstandingSnoop
.find(pkt
->req
) ==
610 outstandingSnoop
.end();
612 if (!forwardAsSnoop
) {
613 // the packet came from this cache, so sink it here and do not
615 assert(pkt
->cmd
== MemCmd::HardPFResp
);
617 outstandingSnoop
.erase(pkt
->req
);
619 DPRINTF(Cache
, "Got prefetch response from above for addr "
620 "%#llx (%s)\n", pkt
->getAddr(), pkt
->isSecure() ? "s" : "ns");
625 // forwardLatency is set here because there is a response from an
626 // upper level cache.
627 // To pay the delay that occurs if the packet comes from the bus,
628 // we charge also headerDelay.
629 Tick snoop_resp_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
630 // Reset the timing of the packet.
631 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
632 memSidePort
->schedTimingSnoopResp(pkt
, snoop_resp_time
);
636 Cache::promoteWholeLineWrites(PacketPtr pkt
)
638 // Cache line clearing instructions
639 if (doFastWrites
&& (pkt
->cmd
== MemCmd::WriteReq
) &&
640 (pkt
->getSize() == blkSize
) && (pkt
->getOffset(blkSize
) == 0)) {
641 pkt
->cmd
= MemCmd::WriteLineReq
;
642 DPRINTF(Cache
, "packet promoted from Write to WriteLineReq\n");
647 Cache::recvTimingReq(PacketPtr pkt
)
649 DPRINTF(CacheTags
, "%s tags:\n%s\n", __func__
, tags
->print());
651 assert(pkt
->isRequest());
653 // Just forward the packet if caches are disabled.
654 if (system
->bypassCaches()) {
655 // @todo This should really enqueue the packet rather
656 bool M5_VAR_USED success
= memSidePort
->sendTimingReq(pkt
);
661 promoteWholeLineWrites(pkt
);
663 // Cache maintenance operations have to visit all the caches down
664 // to the specified xbar (PoC, PoU, etc.). Even if a cache above
665 // is responding we forward the packet to the memory below rather
666 // than creating an express snoop.
667 if (pkt
->cacheResponding()) {
668 // a cache above us (but not where the packet came from) is
669 // responding to the request, in other words it has the line
670 // in Modified or Owned state
671 DPRINTF(Cache
, "Cache above responding to %s: not responding\n",
674 // if the packet needs the block to be writable, and the cache
675 // that has promised to respond (setting the cache responding
676 // flag) is not providing writable (it is in Owned rather than
677 // the Modified state), we know that there may be other Shared
678 // copies in the system; go out and invalidate them all
679 assert(pkt
->needsWritable() && !pkt
->responderHadWritable());
681 // an upstream cache that had the line in Owned state
682 // (dirty, but not writable), is responding and thus
683 // transferring the dirty line from one branch of the
684 // cache hierarchy to another
686 // send out an express snoop and invalidate all other
687 // copies (snooping a packet that needs writable is the
688 // same as an invalidation), thus turning the Owned line
689 // into a Modified line, note that we don't invalidate the
690 // block in the current cache or any other cache on the
693 // create a downstream express snoop with cleared packet
694 // flags, there is no need to allocate any data as the
695 // packet is merely used to co-ordinate state transitions
696 Packet
*snoop_pkt
= new Packet(pkt
, true, false);
698 // also reset the bus time that the original packet has
700 snoop_pkt
->headerDelay
= snoop_pkt
->payloadDelay
= 0;
702 // make this an instantaneous express snoop, and let the
703 // other caches in the system know that the another cache
704 // is responding, because we have found the authorative
705 // copy (Modified or Owned) that will supply the right
707 snoop_pkt
->setExpressSnoop();
708 snoop_pkt
->setCacheResponding();
710 // this express snoop travels towards the memory, and at
711 // every crossbar it is snooped upwards thus reaching
712 // every cache in the system
713 bool M5_VAR_USED success
= memSidePort
->sendTimingReq(snoop_pkt
);
714 // express snoops always succeed
717 // main memory will delete the snoop packet
719 // queue for deletion, as opposed to immediate deletion, as
720 // the sending cache is still relying on the packet
721 pendingDelete
.reset(pkt
);
723 // no need to take any further action in this particular cache
724 // as an upstram cache has already committed to responding,
725 // and we have already sent out any express snoops in the
726 // section above to ensure all other copies in the system are
731 // anything that is merely forwarded pays for the forward latency and
732 // the delay provided by the crossbar
733 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
735 // We use lookupLatency here because it is used to specify the latency
737 Cycles lat
= lookupLatency
;
738 CacheBlk
*blk
= nullptr;
739 bool satisfied
= false;
741 PacketList writebacks
;
742 // Note that lat is passed by reference here. The function
743 // access() calls accessBlock() which can modify lat value.
744 satisfied
= access(pkt
, blk
, lat
, writebacks
);
746 // copy writebacks to write buffer here to ensure they logically
747 // proceed anything happening below
748 doWritebacks(writebacks
, forward_time
);
751 // Here we charge the headerDelay that takes into account the latencies
752 // of the bus, if the packet comes from it.
753 // The latency charged it is just lat that is the value of lookupLatency
754 // modified by access() function, or if not just lookupLatency.
755 // In case of a hit we are neglecting response latency.
756 // In case of a miss we are neglecting forward latency.
757 Tick request_time
= clockEdge(lat
) + pkt
->headerDelay
;
758 // Here we reset the timing of the packet.
759 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
761 // track time of availability of next prefetch, if any
762 Tick next_pf_time
= MaxTick
;
764 bool needsResponse
= pkt
->needsResponse();
767 // should never be satisfying an uncacheable access as we
768 // flush and invalidate any existing block as part of the
770 assert(!pkt
->req
->isUncacheable());
772 // hit (for all other request types)
774 if (prefetcher
&& (prefetchOnAccess
||
775 (blk
&& blk
->wasPrefetched()))) {
777 blk
->status
&= ~BlkHWPrefetched
;
779 // Don't notify on SWPrefetch
780 if (!pkt
->cmd
.isSWPrefetch()) {
781 assert(!pkt
->req
->isCacheMaintenance());
782 next_pf_time
= prefetcher
->notify(pkt
);
787 pkt
->makeTimingResponse();
788 // @todo: Make someone pay for this
789 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
791 // In this case we are considering request_time that takes
792 // into account the delay of the xbar, if any, and just
793 // lat, neglecting responseLatency, modelling hit latency
794 // just as lookupLatency or or the value of lat overriden
795 // by access(), that calls accessBlock() function.
796 cpuSidePort
->schedTimingResp(pkt
, request_time
, true);
798 DPRINTF(Cache
, "%s satisfied %s, no response needed\n", __func__
,
801 // queue the packet for deletion, as the sending cache is
802 // still relying on it; if the block is found in access(),
803 // CleanEvict and Writeback messages will be deleted
805 pendingDelete
.reset(pkt
);
810 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
812 // ignore any existing MSHR if we are dealing with an
813 // uncacheable request
814 MSHR
*mshr
= pkt
->req
->isUncacheable() ? nullptr :
815 mshrQueue
.findMatch(blk_addr
, pkt
->isSecure());
817 // Software prefetch handling:
818 // To keep the core from waiting on data it won't look at
819 // anyway, send back a response with dummy data. Miss handling
820 // will continue asynchronously. Unfortunately, the core will
821 // insist upon freeing original Packet/Request, so we have to
822 // create a new pair with a different lifecycle. Note that this
823 // processing happens before any MSHR munging on the behalf of
824 // this request because this new Request will be the one stored
825 // into the MSHRs, not the original.
826 if (pkt
->cmd
.isSWPrefetch()) {
827 assert(needsResponse
);
828 assert(pkt
->req
->hasPaddr());
829 assert(!pkt
->req
->isUncacheable());
831 // There's no reason to add a prefetch as an additional target
832 // to an existing MSHR. If an outstanding request is already
833 // in progress, there is nothing for the prefetch to do.
834 // If this is the case, we don't even create a request at all.
835 PacketPtr pf
= nullptr;
838 // copy the request and create a new SoftPFReq packet
839 RequestPtr req
= new Request(pkt
->req
->getPaddr(),
841 pkt
->req
->getFlags(),
842 pkt
->req
->masterId());
843 pf
= new Packet(req
, pkt
->cmd
);
845 assert(pf
->getAddr() == pkt
->getAddr());
846 assert(pf
->getSize() == pkt
->getSize());
849 pkt
->makeTimingResponse();
851 // request_time is used here, taking into account lat and the delay
852 // charged if the packet comes from the xbar.
853 cpuSidePort
->schedTimingResp(pkt
, request_time
, true);
855 // If an outstanding request is in progress (we found an
856 // MSHR) this is set to null
862 /// @note writebacks will be checked in getNextMSHR()
863 /// for any conflicting requests to the same block
865 //@todo remove hw_pf here
867 // Coalesce unless it was a software prefetch (see above).
869 assert(!pkt
->isWriteback());
870 // CleanEvicts corresponding to blocks which have
871 // outstanding requests in MSHRs are simply sunk here
872 if (pkt
->cmd
== MemCmd::CleanEvict
) {
873 pendingDelete
.reset(pkt
);
874 } else if (pkt
->cmd
== MemCmd::WriteClean
) {
875 // A WriteClean should never coalesce with any
876 // outstanding cache maintenance requests.
878 // We use forward_time here because there is an
879 // uncached memory write, forwarded to WriteBuffer.
880 allocateWriteBuffer(pkt
, forward_time
);
882 DPRINTF(Cache
, "%s coalescing MSHR for %s\n", __func__
,
885 assert(pkt
->req
->masterId() < system
->maxMasters());
886 mshr_hits
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
887 // We use forward_time here because it is the same
888 // considering new targets. We have multiple
889 // requests for the same address here. It
890 // specifies the latency to allocate an internal
891 // buffer and to schedule an event to the queued
892 // port and also takes into account the additional
893 // delay of the xbar.
894 mshr
->allocateTarget(pkt
, forward_time
, order
++,
895 allocOnFill(pkt
->cmd
));
896 if (mshr
->getNumTargets() == numTarget
) {
898 setBlocked(Blocked_NoTargets
);
899 // need to be careful with this... if this mshr isn't
900 // ready yet (i.e. time > curTick()), we don't want to
901 // move it ahead of mshrs that are ready
902 // mshrQueue.moveToFront(mshr);
905 // We should call the prefetcher reguardless if the request is
906 // satisfied or not, reguardless if the request is in the MSHR
907 // or not. The request could be a ReadReq hit, but still not
908 // satisfied (potentially because of a prior write to the same
909 // cache line. So, even when not satisfied, tehre is an MSHR
910 // already allocated for this, we need to let the prefetcher
911 // know about the request
913 // Don't notify on SWPrefetch
914 if (!pkt
->cmd
.isSWPrefetch() &&
915 !pkt
->req
->isCacheMaintenance())
916 next_pf_time
= prefetcher
->notify(pkt
);
921 assert(pkt
->req
->masterId() < system
->maxMasters());
922 if (pkt
->req
->isUncacheable()) {
923 mshr_uncacheable
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
925 mshr_misses
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
928 if (pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
||
929 (pkt
->req
->isUncacheable() && pkt
->isWrite())) {
930 // We use forward_time here because there is an
931 // uncached memory write, forwarded to WriteBuffer.
932 allocateWriteBuffer(pkt
, forward_time
);
934 if (blk
&& blk
->isValid()) {
935 // should have flushed and have no valid block
936 assert(!pkt
->req
->isUncacheable());
938 // If we have a write miss to a valid block, we
939 // need to mark the block non-readable. Otherwise
940 // if we allow reads while there's an outstanding
941 // write miss, the read could return stale data
942 // out of the cache block... a more aggressive
943 // system could detect the overlap (if any) and
944 // forward data out of the MSHRs, but we don't do
945 // that yet. Note that we do need to leave the
946 // block valid so that it stays in the cache, in
947 // case we get an upgrade response (and hence no
948 // new data) when the write miss completes.
949 // As long as CPUs do proper store/load forwarding
950 // internally, and have a sufficiently weak memory
951 // model, this is probably unnecessary, but at some
952 // point it must have seemed like we needed it...
953 assert((pkt
->needsWritable() && !blk
->isWritable()) ||
954 pkt
->req
->isCacheMaintenance());
955 blk
->status
&= ~BlkReadable
;
957 // Here we are using forward_time, modelling the latency of
958 // a miss (outbound) just as forwardLatency, neglecting the
959 // lookupLatency component.
960 allocateMissBuffer(pkt
, forward_time
);
964 // Don't notify on SWPrefetch
965 if (!pkt
->cmd
.isSWPrefetch() &&
966 !pkt
->req
->isCacheMaintenance())
967 next_pf_time
= prefetcher
->notify(pkt
);
972 if (next_pf_time
!= MaxTick
)
973 schedMemSideSendEvent(next_pf_time
);
979 Cache::createMissPacket(PacketPtr cpu_pkt
, CacheBlk
*blk
,
980 bool needsWritable
) const
982 // should never see evictions here
983 assert(!cpu_pkt
->isEviction());
985 bool blkValid
= blk
&& blk
->isValid();
987 if (cpu_pkt
->req
->isUncacheable() ||
988 (!blkValid
&& cpu_pkt
->isUpgrade()) ||
989 cpu_pkt
->cmd
== MemCmd::InvalidateReq
|| cpu_pkt
->isClean()) {
990 // uncacheable requests and upgrades from upper-level caches
991 // that missed completely just go through as is
995 assert(cpu_pkt
->needsResponse());
998 // @TODO make useUpgrades a parameter.
999 // Note that ownership protocols require upgrade, otherwise a
1000 // write miss on a shared owned block will generate a ReadExcl,
1001 // which will clobber the owned copy.
1002 const bool useUpgrades
= true;
1003 if (cpu_pkt
->cmd
== MemCmd::WriteLineReq
) {
1004 assert(!blkValid
|| !blk
->isWritable());
1005 // forward as invalidate to all other caches, this gives us
1006 // the line in Exclusive state, and invalidates all other
1008 cmd
= MemCmd::InvalidateReq
;
1009 } else if (blkValid
&& useUpgrades
) {
1010 // only reason to be here is that blk is read only and we need
1011 // it to be writable
1012 assert(needsWritable
);
1013 assert(!blk
->isWritable());
1014 cmd
= cpu_pkt
->isLLSC() ? MemCmd::SCUpgradeReq
: MemCmd::UpgradeReq
;
1015 } else if (cpu_pkt
->cmd
== MemCmd::SCUpgradeFailReq
||
1016 cpu_pkt
->cmd
== MemCmd::StoreCondFailReq
) {
1017 // Even though this SC will fail, we still need to send out the
1018 // request and get the data to supply it to other snoopers in the case
1019 // where the determination the StoreCond fails is delayed due to
1020 // all caches not being on the same local bus.
1021 cmd
= MemCmd::SCUpgradeFailReq
;
1024 cmd
= needsWritable
? MemCmd::ReadExReq
:
1025 (isReadOnly
? MemCmd::ReadCleanReq
: MemCmd::ReadSharedReq
);
1027 PacketPtr pkt
= new Packet(cpu_pkt
->req
, cmd
, blkSize
);
1029 // if there are upstream caches that have already marked the
1030 // packet as having sharers (not passing writable), pass that info
1032 if (cpu_pkt
->hasSharers() && !needsWritable
) {
1033 // note that cpu_pkt may have spent a considerable time in the
1034 // MSHR queue and that the information could possibly be out
1035 // of date, however, there is no harm in conservatively
1036 // assuming the block has sharers
1037 pkt
->setHasSharers();
1038 DPRINTF(Cache
, "%s: passing hasSharers from %s to %s\n",
1039 __func__
, cpu_pkt
->print(), pkt
->print());
1042 // the packet should be block aligned
1043 assert(pkt
->getAddr() == pkt
->getBlockAddr(blkSize
));
1046 DPRINTF(Cache
, "%s: created %s from %s\n", __func__
, pkt
->print(),
1053 Cache::recvAtomic(PacketPtr pkt
)
1055 // We are in atomic mode so we pay just for lookupLatency here.
1056 Cycles lat
= lookupLatency
;
1058 // Forward the request if the system is in cache bypass mode.
1059 if (system
->bypassCaches())
1060 return ticksToCycles(memSidePort
->sendAtomic(pkt
));
1062 promoteWholeLineWrites(pkt
);
1064 // follow the same flow as in recvTimingReq, and check if a cache
1065 // above us is responding
1066 if (pkt
->cacheResponding() && !pkt
->isClean()) {
1067 assert(!pkt
->req
->isCacheInvalidate());
1068 DPRINTF(Cache
, "Cache above responding to %s: not responding\n",
1071 // if a cache is responding, and it had the line in Owned
1072 // rather than Modified state, we need to invalidate any
1073 // copies that are not on the same path to memory
1074 assert(pkt
->needsWritable() && !pkt
->responderHadWritable());
1075 lat
+= ticksToCycles(memSidePort
->sendAtomic(pkt
));
1077 return lat
* clockPeriod();
1080 // should assert here that there are no outstanding MSHRs or
1081 // writebacks... that would mean that someone used an atomic
1082 // access in timing mode
1084 CacheBlk
*blk
= nullptr;
1085 PacketList writebacks
;
1086 bool satisfied
= access(pkt
, blk
, lat
, writebacks
);
1088 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
1089 // A cache clean opearation is looking for a dirty
1090 // block. If a dirty block is encountered a WriteClean
1091 // will update any copies to the path to the memory
1092 // until the point of reference.
1093 DPRINTF(CacheVerbose
, "%s: packet %s found block: %s\n",
1094 __func__
, pkt
->print(), blk
->print());
1095 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest());
1096 writebacks
.push_back(wb_pkt
);
1097 pkt
->setSatisfied();
1100 // handle writebacks resulting from the access here to ensure they
1101 // logically proceed anything happening below
1102 doWritebacksAtomic(writebacks
);
1107 // deal with the packets that go through the write path of
1108 // the cache, i.e. any evictions and writes
1109 if (pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
||
1110 (pkt
->req
->isUncacheable() && pkt
->isWrite())) {
1111 lat
+= ticksToCycles(memSidePort
->sendAtomic(pkt
));
1112 return lat
* clockPeriod();
1116 PacketPtr bus_pkt
= createMissPacket(pkt
, blk
, pkt
->needsWritable());
1118 bool is_forward
= (bus_pkt
== nullptr);
1121 // just forwarding the same request to the next level
1122 // no local cache operation involved
1126 DPRINTF(Cache
, "%s: Sending an atomic %s\n", __func__
,
1130 CacheBlk::State old_state
= blk
? blk
->status
: 0;
1133 lat
+= ticksToCycles(memSidePort
->sendAtomic(bus_pkt
));
1135 bool is_invalidate
= bus_pkt
->isInvalidate();
1137 // We are now dealing with the response handling
1138 DPRINTF(Cache
, "%s: Receive response: %s in state %i\n", __func__
,
1139 bus_pkt
->print(), old_state
);
1141 // If packet was a forward, the response (if any) is already
1142 // in place in the bus_pkt == pkt structure, so we don't need
1143 // to do anything. Otherwise, use the separate bus_pkt to
1144 // generate response to pkt and then delete it.
1146 if (pkt
->needsResponse()) {
1147 assert(bus_pkt
->isResponse());
1148 if (bus_pkt
->isError()) {
1149 pkt
->makeAtomicResponse();
1150 pkt
->copyError(bus_pkt
);
1151 } else if (pkt
->cmd
== MemCmd::WriteLineReq
) {
1152 // note the use of pkt, not bus_pkt here.
1154 // write-line request to the cache that promoted
1155 // the write to a whole line
1156 blk
= handleFill(pkt
, blk
, writebacks
,
1157 allocOnFill(pkt
->cmd
));
1158 assert(blk
!= NULL
);
1159 is_invalidate
= false;
1160 satisfyRequest(pkt
, blk
);
1161 } else if (bus_pkt
->isRead() ||
1162 bus_pkt
->cmd
== MemCmd::UpgradeResp
) {
1163 // we're updating cache state to allow us to
1164 // satisfy the upstream request from the cache
1165 blk
= handleFill(bus_pkt
, blk
, writebacks
,
1166 allocOnFill(pkt
->cmd
));
1167 satisfyRequest(pkt
, blk
);
1168 maintainClusivity(pkt
->fromCache(), blk
);
1170 // we're satisfying the upstream request without
1171 // modifying cache state, e.g., a write-through
1172 pkt
->makeAtomicResponse();
1178 if (is_invalidate
&& blk
&& blk
->isValid()) {
1179 invalidateBlock(blk
);
1183 // Note that we don't invoke the prefetcher at all in atomic mode.
1184 // It's not clear how to do it properly, particularly for
1185 // prefetchers that aggressively generate prefetch candidates and
1186 // rely on bandwidth contention to throttle them; these will tend
1187 // to pollute the cache in atomic mode since there is no bandwidth
1188 // contention. If we ever do want to enable prefetching in atomic
1189 // mode, though, this is the place to do it... see timingAccess()
1190 // for an example (though we'd want to issue the prefetch(es)
1191 // immediately rather than calling requestMemSideBus() as we do
1194 // do any writebacks resulting from the response handling
1195 doWritebacksAtomic(writebacks
);
1197 // if we used temp block, check to see if its valid and if so
1198 // clear it out, but only do so after the call to recvAtomic is
1199 // finished so that any downstream observers (such as a snoop
1200 // filter), first see the fill, and only then see the eviction
1201 if (blk
== tempBlock
&& tempBlock
->isValid()) {
1202 // the atomic CPU calls recvAtomic for fetch and load/store
1203 // sequentuially, and we may already have a tempBlock
1204 // writeback from the fetch that we have not yet sent
1205 if (tempBlockWriteback
) {
1206 // if that is the case, write the prevoius one back, and
1207 // do not schedule any new event
1208 writebackTempBlockAtomic();
1210 // the writeback/clean eviction happens after the call to
1211 // recvAtomic has finished (but before any successive
1212 // calls), so that the response handling from the fill is
1213 // allowed to happen first
1214 schedule(writebackTempBlockAtomicEvent
, curTick());
1217 tempBlockWriteback
= (blk
->isDirty() || writebackClean
) ?
1218 writebackBlk(blk
) : cleanEvictBlk(blk
);
1219 invalidateBlock(blk
);
1222 if (pkt
->needsResponse()) {
1223 pkt
->makeAtomicResponse();
1226 return lat
* clockPeriod();
1231 Cache::functionalAccess(PacketPtr pkt
, bool fromCpuSide
)
1233 if (system
->bypassCaches()) {
1234 // Packets from the memory side are snoop request and
1235 // shouldn't happen in bypass mode.
1236 assert(fromCpuSide
);
1238 // The cache should be flushed if we are in cache bypass mode,
1239 // so we don't need to check if we need to update anything.
1240 memSidePort
->sendFunctional(pkt
);
1244 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
1245 bool is_secure
= pkt
->isSecure();
1246 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), is_secure
);
1247 MSHR
*mshr
= mshrQueue
.findMatch(blk_addr
, is_secure
);
1249 pkt
->pushLabel(name());
1251 CacheBlkPrintWrapper
cbpw(blk
);
1253 // Note that just because an L2/L3 has valid data doesn't mean an
1254 // L1 doesn't have a more up-to-date modified copy that still
1255 // needs to be found. As a result we always update the request if
1256 // we have it, but only declare it satisfied if we are the owner.
1258 // see if we have data at all (owned or otherwise)
1259 bool have_data
= blk
&& blk
->isValid()
1260 && pkt
->checkFunctional(&cbpw
, blk_addr
, is_secure
, blkSize
,
1263 // data we have is dirty if marked as such or if we have an
1264 // in-service MSHR that is pending a modified line
1266 have_data
&& (blk
->isDirty() ||
1267 (mshr
&& mshr
->inService
&& mshr
->isPendingModified()));
1269 bool done
= have_dirty
1270 || cpuSidePort
->checkFunctional(pkt
)
1271 || mshrQueue
.checkFunctional(pkt
, blk_addr
)
1272 || writeBuffer
.checkFunctional(pkt
, blk_addr
)
1273 || memSidePort
->checkFunctional(pkt
);
1275 DPRINTF(CacheVerbose
, "%s: %s %s%s%s\n", __func__
, pkt
->print(),
1276 (blk
&& blk
->isValid()) ? "valid " : "",
1277 have_data
? "data " : "", done
? "done " : "");
1279 // We're leaving the cache, so pop cache->name() label
1283 pkt
->makeResponse();
1285 // if it came as a request from the CPU side then make sure it
1286 // continues towards the memory side
1288 memSidePort
->sendFunctional(pkt
);
1289 } else if (cpuSidePort
->isSnooping()) {
1290 // if it came from the memory side, it must be a snoop request
1291 // and we should only forward it if we are forwarding snoops
1292 cpuSidePort
->sendFunctionalSnoop(pkt
);
1298 /////////////////////////////////////////////////////
1300 // Response handling: responses from the memory side
1302 /////////////////////////////////////////////////////
1306 Cache::handleUncacheableWriteResp(PacketPtr pkt
)
1308 Tick completion_time
= clockEdge(responseLatency
) +
1309 pkt
->headerDelay
+ pkt
->payloadDelay
;
1311 // Reset the bus additional time as it is now accounted for
1312 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
1314 cpuSidePort
->schedTimingResp(pkt
, completion_time
, true);
1318 Cache::recvTimingResp(PacketPtr pkt
)
1320 assert(pkt
->isResponse());
1322 // all header delay should be paid for by the crossbar, unless
1323 // this is a prefetch response from above
1324 panic_if(pkt
->headerDelay
!= 0 && pkt
->cmd
!= MemCmd::HardPFResp
,
1325 "%s saw a non-zero packet delay\n", name());
1327 bool is_error
= pkt
->isError();
1330 DPRINTF(Cache
, "%s: Cache received %s with error\n", __func__
,
1334 DPRINTF(Cache
, "%s: Handling response %s\n", __func__
,
1337 // if this is a write, we should be looking at an uncacheable
1339 if (pkt
->isWrite()) {
1340 assert(pkt
->req
->isUncacheable());
1341 handleUncacheableWriteResp(pkt
);
1345 // we have dealt with any (uncacheable) writes above, from here on
1346 // we know we are dealing with an MSHR due to a miss or a prefetch
1347 MSHR
*mshr
= dynamic_cast<MSHR
*>(pkt
->popSenderState());
1350 if (mshr
== noTargetMSHR
) {
1351 // we always clear at least one target
1352 clearBlocked(Blocked_NoTargets
);
1353 noTargetMSHR
= nullptr;
1356 // Initial target is used just for stats
1357 MSHR::Target
*initial_tgt
= mshr
->getTarget();
1358 int stats_cmd_idx
= initial_tgt
->pkt
->cmdToIndex();
1359 Tick miss_latency
= curTick() - initial_tgt
->recvTime
;
1361 if (pkt
->req
->isUncacheable()) {
1362 assert(pkt
->req
->masterId() < system
->maxMasters());
1363 mshr_uncacheable_lat
[stats_cmd_idx
][pkt
->req
->masterId()] +=
1366 assert(pkt
->req
->masterId() < system
->maxMasters());
1367 mshr_miss_latency
[stats_cmd_idx
][pkt
->req
->masterId()] +=
1371 bool wasFull
= mshrQueue
.isFull();
1373 PacketList writebacks
;
1375 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
1377 bool is_fill
= !mshr
->isForward
&&
1378 (pkt
->isRead() || pkt
->cmd
== MemCmd::UpgradeResp
);
1380 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), pkt
->isSecure());
1381 const bool valid_blk
= blk
&& blk
->isValid();
1382 // If the response indicates that there are no sharers and we
1383 // either had the block already or the response is filling we can
1384 // promote our copy to writable
1385 if (!pkt
->hasSharers() &&
1386 (is_fill
|| (valid_blk
&& !pkt
->req
->isCacheInvalidate()))) {
1387 mshr
->promoteWritable();
1390 if (is_fill
&& !is_error
) {
1391 DPRINTF(Cache
, "Block for addr %#llx being updated in Cache\n",
1394 blk
= handleFill(pkt
, blk
, writebacks
, mshr
->allocOnFill());
1395 assert(blk
!= nullptr);
1398 // allow invalidation responses originating from write-line
1399 // requests to be discarded
1400 bool is_invalidate
= pkt
->isInvalidate();
1402 // The block was marked as not readable while there was a pending
1403 // cache maintenance operation, restore its flag.
1404 if (pkt
->isClean() && !is_invalidate
&& valid_blk
) {
1405 blk
->status
|= BlkReadable
;
1408 // First offset for critical word first calculations
1409 int initial_offset
= initial_tgt
->pkt
->getOffset(blkSize
);
1411 bool from_cache
= false;
1412 MSHR::TargetList targets
= mshr
->extractServiceableTargets(pkt
);
1413 for (auto &target
: targets
) {
1414 Packet
*tgt_pkt
= target
.pkt
;
1415 switch (target
.source
) {
1416 case MSHR::Target::FromCPU
:
1417 Tick completion_time
;
1418 // Here we charge on completion_time the delay of the xbar if the
1419 // packet comes from it, charged on headerDelay.
1420 completion_time
= pkt
->headerDelay
;
1422 // Software prefetch handling for cache closest to core
1423 if (tgt_pkt
->cmd
.isSWPrefetch()) {
1424 // a software prefetch would have already been ack'd
1425 // immediately with dummy data so the core would be able to
1426 // retire it. This request completes right here, so we
1428 delete tgt_pkt
->req
;
1430 break; // skip response
1433 // keep track of whether we have responded to another
1435 from_cache
= from_cache
|| tgt_pkt
->fromCache();
1437 // unlike the other packet flows, where data is found in other
1438 // caches or memory and brought back, write-line requests always
1439 // have the data right away, so the above check for "is fill?"
1440 // cannot actually be determined until examining the stored MSHR
1441 // state. We "catch up" with that logic here, which is duplicated
1443 if (tgt_pkt
->cmd
== MemCmd::WriteLineReq
) {
1445 // we got the block in a writable state, so promote
1446 // any deferred targets if possible
1447 mshr
->promoteWritable();
1448 // NB: we use the original packet here and not the response!
1449 blk
= handleFill(tgt_pkt
, blk
, writebacks
,
1450 targets
.allocOnFill
);
1451 assert(blk
!= nullptr);
1453 // treat as a fill, and discard the invalidation
1456 is_invalidate
= false;
1460 satisfyRequest(tgt_pkt
, blk
, true, mshr
->hasPostDowngrade());
1462 // How many bytes past the first request is this one
1463 int transfer_offset
=
1464 tgt_pkt
->getOffset(blkSize
) - initial_offset
;
1465 if (transfer_offset
< 0) {
1466 transfer_offset
+= blkSize
;
1469 // If not critical word (offset) return payloadDelay.
1470 // responseLatency is the latency of the return path
1471 // from lower level caches/memory to an upper level cache or
1473 completion_time
+= clockEdge(responseLatency
) +
1474 (transfer_offset
? pkt
->payloadDelay
: 0);
1476 assert(!tgt_pkt
->req
->isUncacheable());
1478 assert(tgt_pkt
->req
->masterId() < system
->maxMasters());
1479 missLatency
[tgt_pkt
->cmdToIndex()][tgt_pkt
->req
->masterId()] +=
1480 completion_time
- target
.recvTime
;
1481 } else if (pkt
->cmd
== MemCmd::UpgradeFailResp
) {
1482 // failed StoreCond upgrade
1483 assert(tgt_pkt
->cmd
== MemCmd::StoreCondReq
||
1484 tgt_pkt
->cmd
== MemCmd::StoreCondFailReq
||
1485 tgt_pkt
->cmd
== MemCmd::SCUpgradeFailReq
);
1486 // responseLatency is the latency of the return path
1487 // from lower level caches/memory to an upper level cache or
1489 completion_time
+= clockEdge(responseLatency
) +
1491 tgt_pkt
->req
->setExtraData(0);
1493 // We are about to send a response to a cache above
1494 // that asked for an invalidation; we need to
1495 // invalidate our copy immediately as the most
1496 // up-to-date copy of the block will now be in the
1497 // cache above. It will also prevent this cache from
1498 // responding (if the block was previously dirty) to
1499 // snoops as they should snoop the caches above where
1500 // they will get the response from.
1501 if (is_invalidate
&& blk
&& blk
->isValid()) {
1502 invalidateBlock(blk
);
1504 // not a cache fill, just forwarding response
1505 // responseLatency is the latency of the return path
1506 // from lower level cahces/memory to the core.
1507 completion_time
+= clockEdge(responseLatency
) +
1509 if (pkt
->isRead() && !is_error
) {
1511 assert(pkt
->getAddr() == tgt_pkt
->getAddr());
1512 assert(pkt
->getSize() >= tgt_pkt
->getSize());
1514 tgt_pkt
->setData(pkt
->getConstPtr
<uint8_t>());
1517 tgt_pkt
->makeTimingResponse();
1518 // if this packet is an error copy that to the new packet
1520 tgt_pkt
->copyError(pkt
);
1521 if (tgt_pkt
->cmd
== MemCmd::ReadResp
&&
1522 (is_invalidate
|| mshr
->hasPostInvalidate())) {
1523 // If intermediate cache got ReadRespWithInvalidate,
1524 // propagate that. Response should not have
1525 // isInvalidate() set otherwise.
1526 tgt_pkt
->cmd
= MemCmd::ReadRespWithInvalidate
;
1527 DPRINTF(Cache
, "%s: updated cmd to %s\n", __func__
,
1530 // Reset the bus additional time as it is now accounted for
1531 tgt_pkt
->headerDelay
= tgt_pkt
->payloadDelay
= 0;
1532 cpuSidePort
->schedTimingResp(tgt_pkt
, completion_time
, true);
1535 case MSHR::Target::FromPrefetcher
:
1536 assert(tgt_pkt
->cmd
== MemCmd::HardPFReq
);
1538 blk
->status
|= BlkHWPrefetched
;
1539 delete tgt_pkt
->req
;
1543 case MSHR::Target::FromSnoop
:
1544 // I don't believe that a snoop can be in an error state
1546 // response to snoop request
1547 DPRINTF(Cache
, "processing deferred snoop...\n");
1548 // If the response is invalidating, a snooping target can
1549 // be satisfied if it is also invalidating. If the reponse is, not
1550 // only invalidating, but more specifically an InvalidateResp and
1551 // the MSHR was created due to an InvalidateReq then a cache above
1552 // is waiting to satisfy a WriteLineReq. In this case even an
1553 // non-invalidating snoop is added as a target here since this is
1554 // the ordering point. When the InvalidateResp reaches this cache,
1555 // the snooping target will snoop further the cache above with the
1557 assert(!is_invalidate
|| pkt
->cmd
== MemCmd::InvalidateResp
||
1558 pkt
->req
->isCacheMaintenance() ||
1559 mshr
->hasPostInvalidate());
1560 handleSnoop(tgt_pkt
, blk
, true, true, mshr
->hasPostInvalidate());
1564 panic("Illegal target->source enum %d\n", target
.source
);
1568 maintainClusivity(from_cache
, blk
);
1570 if (blk
&& blk
->isValid()) {
1571 // an invalidate response stemming from a write line request
1572 // should not invalidate the block, so check if the
1573 // invalidation should be discarded
1574 if (is_invalidate
|| mshr
->hasPostInvalidate()) {
1575 invalidateBlock(blk
);
1576 } else if (mshr
->hasPostDowngrade()) {
1577 blk
->status
&= ~BlkWritable
;
1581 if (mshr
->promoteDeferredTargets()) {
1582 // avoid later read getting stale data while write miss is
1583 // outstanding.. see comment in timingAccess()
1585 blk
->status
&= ~BlkReadable
;
1587 mshrQueue
.markPending(mshr
);
1588 schedMemSideSendEvent(clockEdge() + pkt
->payloadDelay
);
1590 mshrQueue
.deallocate(mshr
);
1591 if (wasFull
&& !mshrQueue
.isFull()) {
1592 clearBlocked(Blocked_NoMSHRs
);
1595 // Request the bus for a prefetch if this deallocation freed enough
1596 // MSHRs for a prefetch to take place
1597 if (prefetcher
&& mshrQueue
.canPrefetch()) {
1598 Tick next_pf_time
= std::max(prefetcher
->nextPrefetchReadyTime(),
1600 if (next_pf_time
!= MaxTick
)
1601 schedMemSideSendEvent(next_pf_time
);
1604 // reset the xbar additional timinig as it is now accounted for
1605 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
1607 // copy writebacks to write buffer
1608 doWritebacks(writebacks
, forward_time
);
1610 // if we used temp block, check to see if its valid and then clear it out
1611 if (blk
== tempBlock
&& tempBlock
->isValid()) {
1612 // We use forwardLatency here because we are copying
1613 // Writebacks/CleanEvicts to write buffer. It specifies the latency to
1614 // allocate an internal buffer and to schedule an event to the
1616 if (blk
->isDirty() || writebackClean
) {
1617 PacketPtr wbPkt
= writebackBlk(blk
);
1618 allocateWriteBuffer(wbPkt
, forward_time
);
1619 // Set BLOCK_CACHED flag if cached above.
1620 if (isCachedAbove(wbPkt
))
1621 wbPkt
->setBlockCached();
1623 PacketPtr wcPkt
= cleanEvictBlk(blk
);
1624 // Check to see if block is cached above. If not allocate
1626 if (isCachedAbove(wcPkt
))
1629 allocateWriteBuffer(wcPkt
, forward_time
);
1631 invalidateBlock(blk
);
1634 DPRINTF(CacheVerbose
, "%s: Leaving with %s\n", __func__
, pkt
->print());
1639 Cache::writebackBlk(CacheBlk
*blk
)
1641 chatty_assert(!isReadOnly
|| writebackClean
,
1642 "Writeback from read-only cache");
1643 assert(blk
&& blk
->isValid() && (blk
->isDirty() || writebackClean
));
1645 writebacks
[Request::wbMasterId
]++;
1647 Request
*req
= new Request(tags
->regenerateBlkAddr(blk
->tag
, blk
->set
),
1648 blkSize
, 0, Request::wbMasterId
);
1649 if (blk
->isSecure())
1650 req
->setFlags(Request::SECURE
);
1652 req
->taskId(blk
->task_id
);
1653 blk
->task_id
= ContextSwitchTaskId::Unknown
;
1654 blk
->tickInserted
= curTick();
1657 new Packet(req
, blk
->isDirty() ?
1658 MemCmd::WritebackDirty
: MemCmd::WritebackClean
);
1660 DPRINTF(Cache
, "Create Writeback %s writable: %d, dirty: %d\n",
1661 pkt
->print(), blk
->isWritable(), blk
->isDirty());
1663 if (blk
->isWritable()) {
1664 // not asserting shared means we pass the block in modified
1665 // state, mark our own block non-writeable
1666 blk
->status
&= ~BlkWritable
;
1668 // we are in the Owned state, tell the receiver
1669 pkt
->setHasSharers();
1672 // make sure the block is not marked dirty
1673 blk
->status
&= ~BlkDirty
;
1676 std::memcpy(pkt
->getPtr
<uint8_t>(), blk
->data
, blkSize
);
1682 Cache::writecleanBlk(CacheBlk
*blk
, Request::Flags dest
)
1684 Request
*req
= new Request(tags
->regenerateBlkAddr(blk
->tag
, blk
->set
),
1685 blkSize
, 0, Request::wbMasterId
);
1686 if (blk
->isSecure()) {
1687 req
->setFlags(Request::SECURE
);
1689 req
->taskId(blk
->task_id
);
1690 blk
->task_id
= ContextSwitchTaskId::Unknown
;
1691 PacketPtr pkt
= new Packet(req
, MemCmd::WriteClean
);
1692 DPRINTF(Cache
, "Create %s writable: %d, dirty: %d\n", pkt
->print(),
1693 blk
->isWritable(), blk
->isDirty());
1694 // make sure the block is not marked dirty
1695 blk
->status
&= ~BlkDirty
;
1697 // We inform the cache below that the block has sharers in the
1698 // system as we retain our copy.
1699 pkt
->setHasSharers();
1701 req
->setFlags(dest
);
1702 pkt
->setWriteThrough();
1704 std::memcpy(pkt
->getPtr
<uint8_t>(), blk
->data
, blkSize
);
1710 Cache::cleanEvictBlk(CacheBlk
*blk
)
1712 assert(!writebackClean
);
1713 assert(blk
&& blk
->isValid() && !blk
->isDirty());
1714 // Creating a zero sized write, a message to the snoop filter
1716 new Request(tags
->regenerateBlkAddr(blk
->tag
, blk
->set
), blkSize
, 0,
1717 Request::wbMasterId
);
1718 if (blk
->isSecure())
1719 req
->setFlags(Request::SECURE
);
1721 req
->taskId(blk
->task_id
);
1722 blk
->task_id
= ContextSwitchTaskId::Unknown
;
1723 blk
->tickInserted
= curTick();
1725 PacketPtr pkt
= new Packet(req
, MemCmd::CleanEvict
);
1727 DPRINTF(Cache
, "Create CleanEvict %s\n", pkt
->print());
1733 Cache::memWriteback()
1735 CacheBlkVisitorWrapper
visitor(*this, &Cache::writebackVisitor
);
1736 tags
->forEachBlk(visitor
);
1740 Cache::memInvalidate()
1742 CacheBlkVisitorWrapper
visitor(*this, &Cache::invalidateVisitor
);
1743 tags
->forEachBlk(visitor
);
1747 Cache::isDirty() const
1749 CacheBlkIsDirtyVisitor visitor
;
1750 tags
->forEachBlk(visitor
);
1752 return visitor
.isDirty();
1756 Cache::writebackVisitor(CacheBlk
&blk
)
1758 if (blk
.isDirty()) {
1759 assert(blk
.isValid());
1761 Request
request(tags
->regenerateBlkAddr(blk
.tag
, blk
.set
),
1762 blkSize
, 0, Request::funcMasterId
);
1763 request
.taskId(blk
.task_id
);
1764 if (blk
.isSecure()) {
1765 request
.setFlags(Request::SECURE
);
1768 Packet
packet(&request
, MemCmd::WriteReq
);
1769 packet
.dataStatic(blk
.data
);
1771 memSidePort
->sendFunctional(&packet
);
1773 blk
.status
&= ~BlkDirty
;
1780 Cache::invalidateVisitor(CacheBlk
&blk
)
1784 warn_once("Invalidating dirty cache lines. Expect things to break.\n");
1786 if (blk
.isValid()) {
1787 assert(!blk
.isDirty());
1788 invalidateBlock(&blk
);
1795 Cache::allocateBlock(Addr addr
, bool is_secure
, PacketList
&writebacks
)
1797 CacheBlk
*blk
= tags
->findVictim(addr
);
1799 // It is valid to return nullptr if there is no victim
1803 if (blk
->isValid()) {
1804 Addr repl_addr
= tags
->regenerateBlkAddr(blk
->tag
, blk
->set
);
1805 MSHR
*repl_mshr
= mshrQueue
.findMatch(repl_addr
, blk
->isSecure());
1807 // must be an outstanding upgrade request
1808 // on a block we're about to replace...
1809 assert(!blk
->isWritable() || blk
->isDirty());
1810 assert(repl_mshr
->needsWritable());
1811 // too hard to replace block with transient state
1812 // allocation failed, block not inserted
1815 DPRINTF(Cache
, "replacement: replacing %#llx (%s) with %#llx "
1816 "(%s): %s\n", repl_addr
, blk
->isSecure() ? "s" : "ns",
1817 addr
, is_secure
? "s" : "ns",
1818 blk
->isDirty() ? "writeback" : "clean");
1820 if (blk
->wasPrefetched()) {
1823 // Will send up Writeback/CleanEvict snoops via isCachedAbove
1824 // when pushing this writeback list into the write buffer.
1825 if (blk
->isDirty() || writebackClean
) {
1826 // Save writeback packet for handling by caller
1827 writebacks
.push_back(writebackBlk(blk
));
1829 writebacks
.push_back(cleanEvictBlk(blk
));
1838 Cache::invalidateBlock(CacheBlk
*blk
)
1840 if (blk
!= tempBlock
)
1841 tags
->invalidate(blk
);
1845 // Note that the reason we return a list of writebacks rather than
1846 // inserting them directly in the write buffer is that this function
1847 // is called by both atomic and timing-mode accesses, and in atomic
1848 // mode we don't mess with the write buffer (we just perform the
1849 // writebacks atomically once the original request is complete).
1851 Cache::handleFill(PacketPtr pkt
, CacheBlk
*blk
, PacketList
&writebacks
,
1854 assert(pkt
->isResponse() || pkt
->cmd
== MemCmd::WriteLineReq
);
1855 Addr addr
= pkt
->getAddr();
1856 bool is_secure
= pkt
->isSecure();
1858 CacheBlk::State old_state
= blk
? blk
->status
: 0;
1861 // When handling a fill, we should have no writes to this line.
1862 assert(addr
== pkt
->getBlockAddr(blkSize
));
1863 assert(!writeBuffer
.findMatch(addr
, is_secure
));
1865 if (blk
== nullptr) {
1866 // better have read new data...
1867 assert(pkt
->hasData());
1869 // only read responses and write-line requests have data;
1870 // note that we don't write the data here for write-line - that
1871 // happens in the subsequent call to satisfyRequest
1872 assert(pkt
->isRead() || pkt
->cmd
== MemCmd::WriteLineReq
);
1874 // need to do a replacement if allocating, otherwise we stick
1875 // with the temporary storage
1876 blk
= allocate
? allocateBlock(addr
, is_secure
, writebacks
) : nullptr;
1878 if (blk
== nullptr) {
1879 // No replaceable block or a mostly exclusive
1880 // cache... just use temporary storage to complete the
1881 // current request and then get rid of it
1882 assert(!tempBlock
->isValid());
1884 tempBlock
->set
= tags
->extractSet(addr
);
1885 tempBlock
->tag
= tags
->extractTag(addr
);
1886 // @todo: set security state as well...
1887 DPRINTF(Cache
, "using temp block for %#llx (%s)\n", addr
,
1888 is_secure
? "s" : "ns");
1890 tags
->insertBlock(pkt
, blk
);
1893 // we should never be overwriting a valid block
1894 assert(!blk
->isValid());
1896 // existing block... probably an upgrade
1897 assert(blk
->tag
== tags
->extractTag(addr
));
1898 // either we're getting new data or the block should already be valid
1899 assert(pkt
->hasData() || blk
->isValid());
1900 // don't clear block status... if block is already dirty we
1901 // don't want to lose that
1905 blk
->status
|= BlkSecure
;
1906 blk
->status
|= BlkValid
| BlkReadable
;
1908 // sanity check for whole-line writes, which should always be
1909 // marked as writable as part of the fill, and then later marked
1910 // dirty as part of satisfyRequest
1911 if (pkt
->cmd
== MemCmd::WriteLineReq
) {
1912 assert(!pkt
->hasSharers());
1915 // here we deal with setting the appropriate state of the line,
1916 // and we start by looking at the hasSharers flag, and ignore the
1917 // cacheResponding flag (normally signalling dirty data) if the
1918 // packet has sharers, thus the line is never allocated as Owned
1919 // (dirty but not writable), and always ends up being either
1920 // Shared, Exclusive or Modified, see Packet::setCacheResponding
1922 if (!pkt
->hasSharers()) {
1923 // we could get a writable line from memory (rather than a
1924 // cache) even in a read-only cache, note that we set this bit
1925 // even for a read-only cache, possibly revisit this decision
1926 blk
->status
|= BlkWritable
;
1928 // check if we got this via cache-to-cache transfer (i.e., from a
1929 // cache that had the block in Modified or Owned state)
1930 if (pkt
->cacheResponding()) {
1931 // we got the block in Modified state, and invalidated the
1933 blk
->status
|= BlkDirty
;
1935 chatty_assert(!isReadOnly
, "Should never see dirty snoop response "
1936 "in read-only cache %s\n", name());
1940 DPRINTF(Cache
, "Block addr %#llx (%s) moving from state %x to %s\n",
1941 addr
, is_secure
? "s" : "ns", old_state
, blk
->print());
1943 // if we got new data, copy it in (checking for a read response
1944 // and a response that has data is the same in the end)
1945 if (pkt
->isRead()) {
1947 assert(pkt
->hasData());
1948 assert(pkt
->getSize() == blkSize
);
1950 std::memcpy(blk
->data
, pkt
->getConstPtr
<uint8_t>(), blkSize
);
1952 // We pay for fillLatency here.
1953 blk
->whenReady
= clockEdge() + fillLatency
* clockPeriod() +
1960 /////////////////////////////////////////////////////
1962 // Snoop path: requests coming in from the memory side
1964 /////////////////////////////////////////////////////
1967 Cache::doTimingSupplyResponse(PacketPtr req_pkt
, const uint8_t *blk_data
,
1968 bool already_copied
, bool pending_inval
)
1971 assert(req_pkt
->isRequest());
1972 assert(req_pkt
->needsResponse());
1974 DPRINTF(Cache
, "%s: for %s\n", __func__
, req_pkt
->print());
1975 // timing-mode snoop responses require a new packet, unless we
1976 // already made a copy...
1977 PacketPtr pkt
= req_pkt
;
1978 if (!already_copied
)
1979 // do not clear flags, and allocate space for data if the
1980 // packet needs it (the only packets that carry data are read
1982 pkt
= new Packet(req_pkt
, false, req_pkt
->isRead());
1984 assert(req_pkt
->req
->isUncacheable() || req_pkt
->isInvalidate() ||
1986 pkt
->makeTimingResponse();
1987 if (pkt
->isRead()) {
1988 pkt
->setDataFromBlock(blk_data
, blkSize
);
1990 if (pkt
->cmd
== MemCmd::ReadResp
&& pending_inval
) {
1991 // Assume we defer a response to a read from a far-away cache
1992 // A, then later defer a ReadExcl from a cache B on the same
1993 // bus as us. We'll assert cacheResponding in both cases, but
1994 // in the latter case cacheResponding will keep the
1995 // invalidation from reaching cache A. This special response
1996 // tells cache A that it gets the block to satisfy its read,
1997 // but must immediately invalidate it.
1998 pkt
->cmd
= MemCmd::ReadRespWithInvalidate
;
2000 // Here we consider forward_time, paying for just forward latency and
2001 // also charging the delay provided by the xbar.
2002 // forward_time is used as send_time in next allocateWriteBuffer().
2003 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
2004 // Here we reset the timing of the packet.
2005 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
2006 DPRINTF(CacheVerbose
, "%s: created response: %s tick: %lu\n", __func__
,
2007 pkt
->print(), forward_time
);
2008 memSidePort
->schedTimingSnoopResp(pkt
, forward_time
, true);
2012 Cache::handleSnoop(PacketPtr pkt
, CacheBlk
*blk
, bool is_timing
,
2013 bool is_deferred
, bool pending_inval
)
2015 DPRINTF(CacheVerbose
, "%s: for %s\n", __func__
, pkt
->print());
2016 // deferred snoops can only happen in timing mode
2017 assert(!(is_deferred
&& !is_timing
));
2018 // pending_inval only makes sense on deferred snoops
2019 assert(!(pending_inval
&& !is_deferred
));
2020 assert(pkt
->isRequest());
2022 // the packet may get modified if we or a forwarded snooper
2023 // responds in atomic mode, so remember a few things about the
2024 // original packet up front
2025 bool invalidate
= pkt
->isInvalidate();
2026 bool M5_VAR_USED needs_writable
= pkt
->needsWritable();
2028 // at the moment we could get an uncacheable write which does not
2029 // have the invalidate flag, and we need a suitable way of dealing
2031 panic_if(invalidate
&& pkt
->req
->isUncacheable(),
2032 "%s got an invalidating uncacheable snoop request %s",
2033 name(), pkt
->print());
2035 uint32_t snoop_delay
= 0;
2037 if (forwardSnoops
) {
2038 // first propagate snoop upward to see if anyone above us wants to
2039 // handle it. save & restore packet src since it will get
2040 // rewritten to be relative to cpu-side bus (if any)
2041 bool alreadyResponded
= pkt
->cacheResponding();
2043 // copy the packet so that we can clear any flags before
2044 // forwarding it upwards, we also allocate data (passing
2045 // the pointer along in case of static data), in case
2046 // there is a snoop hit in upper levels
2047 Packet
snoopPkt(pkt
, true, true);
2048 snoopPkt
.setExpressSnoop();
2049 // the snoop packet does not need to wait any additional
2051 snoopPkt
.headerDelay
= snoopPkt
.payloadDelay
= 0;
2052 cpuSidePort
->sendTimingSnoopReq(&snoopPkt
);
2054 // add the header delay (including crossbar and snoop
2055 // delays) of the upward snoop to the snoop delay for this
2057 snoop_delay
+= snoopPkt
.headerDelay
;
2059 if (snoopPkt
.cacheResponding()) {
2060 // cache-to-cache response from some upper cache
2061 assert(!alreadyResponded
);
2062 pkt
->setCacheResponding();
2064 // upstream cache has the block, or has an outstanding
2065 // MSHR, pass the flag on
2066 if (snoopPkt
.hasSharers()) {
2067 pkt
->setHasSharers();
2069 // If this request is a prefetch or clean evict and an upper level
2070 // signals block present, make sure to propagate the block
2071 // presence to the requester.
2072 if (snoopPkt
.isBlockCached()) {
2073 pkt
->setBlockCached();
2075 // If the request was satisfied by snooping the cache
2076 // above, mark the original packet as satisfied too.
2077 if (snoopPkt
.satisfied()) {
2078 pkt
->setSatisfied();
2081 cpuSidePort
->sendAtomicSnoop(pkt
);
2082 if (!alreadyResponded
&& pkt
->cacheResponding()) {
2083 // cache-to-cache response from some upper cache:
2084 // forward response to original requester
2085 assert(pkt
->isResponse());
2090 bool respond
= false;
2091 bool blk_valid
= blk
&& blk
->isValid();
2092 if (pkt
->isClean()) {
2093 if (blk_valid
&& blk
->isDirty()) {
2094 DPRINTF(CacheVerbose
, "%s: packet (snoop) %s found block: %s\n",
2095 __func__
, pkt
->print(), blk
->print());
2096 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest());
2097 PacketList writebacks
;
2098 writebacks
.push_back(wb_pkt
);
2101 // anything that is merely forwarded pays for the forward
2102 // latency and the delay provided by the crossbar
2103 Tick forward_time
= clockEdge(forwardLatency
) +
2105 doWritebacks(writebacks
, forward_time
);
2107 doWritebacksAtomic(writebacks
);
2109 pkt
->setSatisfied();
2111 } else if (!blk_valid
) {
2112 DPRINTF(CacheVerbose
, "%s: snoop miss for %s\n", __func__
,
2115 // we no longer have the block, and will not respond, but a
2116 // packet was allocated in MSHR::handleSnoop and we have
2118 assert(pkt
->needsResponse());
2120 // we have passed the block to a cache upstream, that
2121 // cache should be responding
2122 assert(pkt
->cacheResponding());
2128 DPRINTF(Cache
, "%s: snoop hit for %s, old state is %s\n", __func__
,
2129 pkt
->print(), blk
->print());
2131 // We may end up modifying both the block state and the packet (if
2132 // we respond in atomic mode), so just figure out what to do now
2133 // and then do it later. We respond to all snoops that need
2134 // responses provided we have the block in dirty state. The
2135 // invalidation itself is taken care of below. We don't respond to
2136 // cache maintenance operations as this is done by the destination
2138 respond
= blk
->isDirty() && pkt
->needsResponse();
2140 chatty_assert(!(isReadOnly
&& blk
->isDirty()), "Should never have "
2141 "a dirty block in a read-only cache %s\n", name());
2144 // Invalidate any prefetch's from below that would strip write permissions
2145 // MemCmd::HardPFReq is only observed by upstream caches. After missing
2146 // above and in it's own cache, a new MemCmd::ReadReq is created that
2147 // downstream caches observe.
2148 if (pkt
->mustCheckAbove()) {
2149 DPRINTF(Cache
, "Found addr %#llx in upper level cache for snoop %s "
2150 "from lower cache\n", pkt
->getAddr(), pkt
->print());
2151 pkt
->setBlockCached();
2155 if (pkt
->isRead() && !invalidate
) {
2156 // reading without requiring the line in a writable state
2157 assert(!needs_writable
);
2158 pkt
->setHasSharers();
2160 // if the requesting packet is uncacheable, retain the line in
2161 // the current state, otherwhise unset the writable flag,
2162 // which means we go from Modified to Owned (and will respond
2163 // below), remain in Owned (and will respond below), from
2164 // Exclusive to Shared, or remain in Shared
2165 if (!pkt
->req
->isUncacheable())
2166 blk
->status
&= ~BlkWritable
;
2167 DPRINTF(Cache
, "new state is %s\n", blk
->print());
2171 // prevent anyone else from responding, cache as well as
2172 // memory, and also prevent any memory from even seeing the
2174 pkt
->setCacheResponding();
2175 if (!pkt
->isClean() && blk
->isWritable()) {
2176 // inform the cache hierarchy that this cache had the line
2177 // in the Modified state so that we avoid unnecessary
2178 // invalidations (see Packet::setResponderHadWritable)
2179 pkt
->setResponderHadWritable();
2181 // in the case of an uncacheable request there is no point
2182 // in setting the responderHadWritable flag, but since the
2183 // recipient does not care there is no harm in doing so
2185 // if the packet has needsWritable set we invalidate our
2186 // copy below and all other copies will be invalidates
2187 // through express snoops, and if needsWritable is not set
2188 // we already called setHasSharers above
2191 // if we are returning a writable and dirty (Modified) line,
2192 // we should be invalidating the line
2193 panic_if(!invalidate
&& !pkt
->hasSharers(),
2194 "%s is passing a Modified line through %s, "
2195 "but keeping the block", name(), pkt
->print());
2198 doTimingSupplyResponse(pkt
, blk
->data
, is_deferred
, pending_inval
);
2200 pkt
->makeAtomicResponse();
2201 // packets such as upgrades do not actually have any data
2204 pkt
->setDataFromBlock(blk
->data
, blkSize
);
2208 if (!respond
&& is_deferred
) {
2209 assert(pkt
->needsResponse());
2211 // if we copied the deferred packet with the intention to
2212 // respond, but are not responding, then a cache above us must
2213 // be, and we can use this as the indication of whether this
2214 // is a packet where we created a copy of the request or not
2215 if (!pkt
->cacheResponding()) {
2222 // Do this last in case it deallocates block data or something
2224 if (blk_valid
&& invalidate
) {
2225 invalidateBlock(blk
);
2226 DPRINTF(Cache
, "new state is %s\n", blk
->print());
2234 Cache::recvTimingSnoopReq(PacketPtr pkt
)
2236 DPRINTF(CacheVerbose
, "%s: for %s\n", __func__
, pkt
->print());
2238 // Snoops shouldn't happen when bypassing caches
2239 assert(!system
->bypassCaches());
2241 // no need to snoop requests that are not in range
2242 if (!inRange(pkt
->getAddr())) {
2246 bool is_secure
= pkt
->isSecure();
2247 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), is_secure
);
2249 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
2250 MSHR
*mshr
= mshrQueue
.findMatch(blk_addr
, is_secure
);
2252 // Update the latency cost of the snoop so that the crossbar can
2253 // account for it. Do not overwrite what other neighbouring caches
2254 // have already done, rather take the maximum. The update is
2255 // tentative, for cases where we return before an upward snoop
2257 pkt
->snoopDelay
= std::max
<uint32_t>(pkt
->snoopDelay
,
2258 lookupLatency
* clockPeriod());
2260 // Inform request(Prefetch, CleanEvict or Writeback) from below of
2261 // MSHR hit, set setBlockCached.
2262 if (mshr
&& pkt
->mustCheckAbove()) {
2263 DPRINTF(Cache
, "Setting block cached for %s from lower cache on "
2264 "mshr hit\n", pkt
->print());
2265 pkt
->setBlockCached();
2269 // Bypass any existing cache maintenance requests if the request
2270 // has been satisfied already (i.e., the dirty block has been
2272 if (mshr
&& pkt
->req
->isCacheMaintenance() && pkt
->satisfied()) {
2276 // Let the MSHR itself track the snoop and decide whether we want
2277 // to go ahead and do the regular cache snoop
2278 if (mshr
&& mshr
->handleSnoop(pkt
, order
++)) {
2279 DPRINTF(Cache
, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
2280 "mshrs: %s\n", blk_addr
, is_secure
? "s" : "ns",
2283 if (mshr
->getNumTargets() > numTarget
)
2284 warn("allocating bonus target for snoop"); //handle later
2288 //We also need to check the writeback buffers and handle those
2289 WriteQueueEntry
*wb_entry
= writeBuffer
.findMatch(blk_addr
, is_secure
);
2291 DPRINTF(Cache
, "Snoop hit in writeback to addr %#llx (%s)\n",
2292 pkt
->getAddr(), is_secure
? "s" : "ns");
2293 // Expect to see only Writebacks and/or CleanEvicts here, both of
2294 // which should not be generated for uncacheable data.
2295 assert(!wb_entry
->isUncacheable());
2296 // There should only be a single request responsible for generating
2297 // Writebacks/CleanEvicts.
2298 assert(wb_entry
->getNumTargets() == 1);
2299 PacketPtr wb_pkt
= wb_entry
->getTarget()->pkt
;
2300 assert(wb_pkt
->isEviction() || wb_pkt
->cmd
== MemCmd::WriteClean
);
2302 if (pkt
->isEviction()) {
2303 // if the block is found in the write queue, set the BLOCK_CACHED
2304 // flag for Writeback/CleanEvict snoop. On return the snoop will
2305 // propagate the BLOCK_CACHED flag in Writeback packets and prevent
2306 // any CleanEvicts from travelling down the memory hierarchy.
2307 pkt
->setBlockCached();
2308 DPRINTF(Cache
, "%s: Squashing %s from lower cache on writequeue "
2309 "hit\n", __func__
, pkt
->print());
2313 // conceptually writebacks are no different to other blocks in
2314 // this cache, so the behaviour is modelled after handleSnoop,
2315 // the difference being that instead of querying the block
2316 // state to determine if it is dirty and writable, we use the
2317 // command and fields of the writeback packet
2318 bool respond
= wb_pkt
->cmd
== MemCmd::WritebackDirty
&&
2319 pkt
->needsResponse();
2320 bool have_writable
= !wb_pkt
->hasSharers();
2321 bool invalidate
= pkt
->isInvalidate();
2323 if (!pkt
->req
->isUncacheable() && pkt
->isRead() && !invalidate
) {
2324 assert(!pkt
->needsWritable());
2325 pkt
->setHasSharers();
2326 wb_pkt
->setHasSharers();
2330 pkt
->setCacheResponding();
2332 if (have_writable
) {
2333 pkt
->setResponderHadWritable();
2336 doTimingSupplyResponse(pkt
, wb_pkt
->getConstPtr
<uint8_t>(),
2340 if (invalidate
&& wb_pkt
->cmd
!= MemCmd::WriteClean
) {
2341 // Invalidation trumps our writeback... discard here
2342 // Note: markInService will remove entry from writeback buffer.
2343 markInService(wb_entry
);
2348 // If this was a shared writeback, there may still be
2349 // other shared copies above that require invalidation.
2350 // We could be more selective and return here if the
2351 // request is non-exclusive or if the writeback is
2353 uint32_t snoop_delay
= handleSnoop(pkt
, blk
, true, false, false);
2355 // Override what we did when we first saw the snoop, as we now
2356 // also have the cost of the upwards snoops to account for
2357 pkt
->snoopDelay
= std::max
<uint32_t>(pkt
->snoopDelay
, snoop_delay
+
2358 lookupLatency
* clockPeriod());
2362 Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt
)
2364 // Express snoop responses from master to slave, e.g., from L1 to L2
2365 cache
->recvTimingSnoopResp(pkt
);
2370 Cache::recvAtomicSnoop(PacketPtr pkt
)
2372 // Snoops shouldn't happen when bypassing caches
2373 assert(!system
->bypassCaches());
2375 // no need to snoop requests that are not in range.
2376 if (!inRange(pkt
->getAddr())) {
2380 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), pkt
->isSecure());
2381 uint32_t snoop_delay
= handleSnoop(pkt
, blk
, false, false, false);
2382 return snoop_delay
+ lookupLatency
* clockPeriod();
2387 Cache::getNextQueueEntry()
2389 // Check both MSHR queue and write buffer for potential requests,
2390 // note that null does not mean there is no request, it could
2391 // simply be that it is not ready
2392 MSHR
*miss_mshr
= mshrQueue
.getNext();
2393 WriteQueueEntry
*wq_entry
= writeBuffer
.getNext();
2395 // If we got a write buffer request ready, first priority is a
2396 // full write buffer, otherwise we favour the miss requests
2397 if (wq_entry
&& (writeBuffer
.isFull() || !miss_mshr
)) {
2398 // need to search MSHR queue for conflicting earlier miss.
2399 MSHR
*conflict_mshr
=
2400 mshrQueue
.findPending(wq_entry
->blkAddr
,
2401 wq_entry
->isSecure
);
2403 if (conflict_mshr
&& conflict_mshr
->order
< wq_entry
->order
) {
2404 // Service misses in order until conflict is cleared.
2405 return conflict_mshr
;
2407 // @todo Note that we ignore the ready time of the conflict here
2410 // No conflicts; issue write
2412 } else if (miss_mshr
) {
2413 // need to check for conflicting earlier writeback
2414 WriteQueueEntry
*conflict_mshr
=
2415 writeBuffer
.findPending(miss_mshr
->blkAddr
,
2416 miss_mshr
->isSecure
);
2417 if (conflict_mshr
) {
2418 // not sure why we don't check order here... it was in the
2419 // original code but commented out.
2421 // The only way this happens is if we are
2422 // doing a write and we didn't have permissions
2423 // then subsequently saw a writeback (owned got evicted)
2424 // We need to make sure to perform the writeback first
2425 // To preserve the dirty data, then we can issue the write
2427 // should we return wq_entry here instead? I.e. do we
2428 // have to flush writes in order? I don't think so... not
2429 // for Alpha anyway. Maybe for x86?
2430 return conflict_mshr
;
2432 // @todo Note that we ignore the ready time of the conflict here
2435 // No conflicts; issue read
2439 // fall through... no pending requests. Try a prefetch.
2440 assert(!miss_mshr
&& !wq_entry
);
2441 if (prefetcher
&& mshrQueue
.canPrefetch()) {
2442 // If we have a miss queue slot, we can try a prefetch
2443 PacketPtr pkt
= prefetcher
->getPacket();
2445 Addr pf_addr
= pkt
->getBlockAddr(blkSize
);
2446 if (!tags
->findBlock(pf_addr
, pkt
->isSecure()) &&
2447 !mshrQueue
.findMatch(pf_addr
, pkt
->isSecure()) &&
2448 !writeBuffer
.findMatch(pf_addr
, pkt
->isSecure())) {
2449 // Update statistic on number of prefetches issued
2450 // (hwpf_mshr_misses)
2451 assert(pkt
->req
->masterId() < system
->maxMasters());
2452 mshr_misses
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
2454 // allocate an MSHR and return it, note
2455 // that we send the packet straight away, so do not
2456 // schedule the send
2457 return allocateMissBuffer(pkt
, curTick(), false);
2459 // free the request and packet
2470 Cache::isCachedAbove(PacketPtr pkt
, bool is_timing
) const
2474 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
2475 // Writeback snoops into upper level caches to check for copies of the
2476 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
2477 // packet, the cache can inform the crossbar below of presence or absence
2480 Packet
snoop_pkt(pkt
, true, false);
2481 snoop_pkt
.setExpressSnoop();
2482 // Assert that packet is either Writeback or CleanEvict and not a
2483 // prefetch request because prefetch requests need an MSHR and may
2484 // generate a snoop response.
2485 assert(pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
);
2486 snoop_pkt
.senderState
= nullptr;
2487 cpuSidePort
->sendTimingSnoopReq(&snoop_pkt
);
2488 // Writeback/CleanEvict snoops do not generate a snoop response.
2489 assert(!(snoop_pkt
.cacheResponding()));
2490 return snoop_pkt
.isBlockCached();
2492 cpuSidePort
->sendAtomicSnoop(pkt
);
2493 return pkt
->isBlockCached();
2498 Cache::nextQueueReadyTime() const
2500 Tick nextReady
= std::min(mshrQueue
.nextReadyTime(),
2501 writeBuffer
.nextReadyTime());
2503 // Don't signal prefetch ready time if no MSHRs available
2504 // Will signal once enoguh MSHRs are deallocated
2505 if (prefetcher
&& mshrQueue
.canPrefetch()) {
2506 nextReady
= std::min(nextReady
,
2507 prefetcher
->nextPrefetchReadyTime());
2514 Cache::sendMSHRQueuePacket(MSHR
* mshr
)
2518 // use request from 1st target
2519 PacketPtr tgt_pkt
= mshr
->getTarget()->pkt
;
2521 DPRINTF(Cache
, "%s: MSHR %s\n", __func__
, tgt_pkt
->print());
2523 CacheBlk
*blk
= tags
->findBlock(mshr
->blkAddr
, mshr
->isSecure
);
2525 if (tgt_pkt
->cmd
== MemCmd::HardPFReq
&& forwardSnoops
) {
2526 // we should never have hardware prefetches to allocated
2528 assert(blk
== nullptr);
2530 // We need to check the caches above us to verify that
2531 // they don't have a copy of this block in the dirty state
2532 // at the moment. Without this check we could get a stale
2533 // copy from memory that might get used in place of the
2535 Packet
snoop_pkt(tgt_pkt
, true, false);
2536 snoop_pkt
.setExpressSnoop();
2537 // We are sending this packet upwards, but if it hits we will
2538 // get a snoop response that we end up treating just like a
2539 // normal response, hence it needs the MSHR as its sender
2541 snoop_pkt
.senderState
= mshr
;
2542 cpuSidePort
->sendTimingSnoopReq(&snoop_pkt
);
2544 // Check to see if the prefetch was squashed by an upper cache (to
2545 // prevent us from grabbing the line) or if a Check to see if a
2546 // writeback arrived between the time the prefetch was placed in
2547 // the MSHRs and when it was selected to be sent or if the
2548 // prefetch was squashed by an upper cache.
2550 // It is important to check cacheResponding before
2551 // prefetchSquashed. If another cache has committed to
2552 // responding, it will be sending a dirty response which will
2553 // arrive at the MSHR allocated for this request. Checking the
2554 // prefetchSquash first may result in the MSHR being
2555 // prematurely deallocated.
2556 if (snoop_pkt
.cacheResponding()) {
2557 auto M5_VAR_USED r
= outstandingSnoop
.insert(snoop_pkt
.req
);
2560 // if we are getting a snoop response with no sharers it
2561 // will be allocated as Modified
2562 bool pending_modified_resp
= !snoop_pkt
.hasSharers();
2563 markInService(mshr
, pending_modified_resp
);
2565 DPRINTF(Cache
, "Upward snoop of prefetch for addr"
2567 tgt_pkt
->getAddr(), tgt_pkt
->isSecure()? "s": "ns");
2571 if (snoop_pkt
.isBlockCached()) {
2572 DPRINTF(Cache
, "Block present, prefetch squashed by cache. "
2573 "Deallocating mshr target %#x.\n",
2576 // Deallocate the mshr target
2577 if (mshrQueue
.forceDeallocateTarget(mshr
)) {
2578 // Clear block if this deallocation resulted freed an
2579 // mshr when all had previously been utilized
2580 clearBlocked(Blocked_NoMSHRs
);
2583 // given that no response is expected, delete Request and Packet
2584 delete tgt_pkt
->req
;
2591 // either a prefetch that is not present upstream, or a normal
2592 // MSHR request, proceed to get the packet to send downstream
2593 PacketPtr pkt
= createMissPacket(tgt_pkt
, blk
, mshr
->needsWritable());
2595 mshr
->isForward
= (pkt
== nullptr);
2597 if (mshr
->isForward
) {
2598 // not a cache block request, but a response is expected
2599 // make copy of current packet to forward, keep current
2600 // copy for response handling
2601 pkt
= new Packet(tgt_pkt
, false, true);
2602 assert(!pkt
->isWrite());
2605 // play it safe and append (rather than set) the sender state,
2606 // as forwarded packets may already have existing state
2607 pkt
->pushSenderState(mshr
);
2609 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
2610 // A cache clean opearation is looking for a dirty block. Mark
2611 // the packet so that the destination xbar can determine that
2612 // there will be a follow-up write packet as well.
2613 pkt
->setSatisfied();
2616 if (!memSidePort
->sendTimingReq(pkt
)) {
2617 // we are awaiting a retry, but we
2618 // delete the packet and will be creating a new packet
2619 // when we get the opportunity
2622 // note that we have now masked any requestBus and
2623 // schedSendEvent (we will wait for a retry before
2624 // doing anything), and this is so even if we do not
2625 // care about this packet and might override it before
2629 // As part of the call to sendTimingReq the packet is
2630 // forwarded to all neighbouring caches (and any caches
2631 // above them) as a snoop. Thus at this point we know if
2632 // any of the neighbouring caches are responding, and if
2633 // so, we know it is dirty, and we can determine if it is
2634 // being passed as Modified, making our MSHR the ordering
2636 bool pending_modified_resp
= !pkt
->hasSharers() &&
2637 pkt
->cacheResponding();
2638 markInService(mshr
, pending_modified_resp
);
2639 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
2640 // A cache clean opearation is looking for a dirty
2641 // block. If a dirty block is encountered a WriteClean
2642 // will update any copies to the path to the memory
2643 // until the point of reference.
2644 DPRINTF(CacheVerbose
, "%s: packet %s found block: %s\n",
2645 __func__
, pkt
->print(), blk
->print());
2646 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest());
2647 PacketList writebacks
;
2648 writebacks
.push_back(wb_pkt
);
2649 doWritebacks(writebacks
, 0);
2657 Cache::sendWriteQueuePacket(WriteQueueEntry
* wq_entry
)
2661 // always a single target for write queue entries
2662 PacketPtr tgt_pkt
= wq_entry
->getTarget()->pkt
;
2664 DPRINTF(Cache
, "%s: write %s\n", __func__
, tgt_pkt
->print());
2666 // forward as is, both for evictions and uncacheable writes
2667 if (!memSidePort
->sendTimingReq(tgt_pkt
)) {
2668 // note that we have now masked any requestBus and
2669 // schedSendEvent (we will wait for a retry before
2670 // doing anything), and this is so even if we do not
2671 // care about this packet and might override it before
2675 markInService(wq_entry
);
2681 Cache::serialize(CheckpointOut
&cp
) const
2683 bool dirty(isDirty());
2686 warn("*** The cache still contains dirty data. ***\n");
2687 warn(" Make sure to drain the system using the correct flags.\n");
2688 warn(" This checkpoint will not restore correctly and dirty data "
2689 " in the cache will be lost!\n");
2692 // Since we don't checkpoint the data in the cache, any dirty data
2693 // will be lost when restoring from a checkpoint of a system that
2694 // wasn't drained properly. Flag the checkpoint as invalid if the
2695 // cache contains dirty data.
2696 bool bad_checkpoint(dirty
);
2697 SERIALIZE_SCALAR(bad_checkpoint
);
2701 Cache::unserialize(CheckpointIn
&cp
)
2703 bool bad_checkpoint
;
2704 UNSERIALIZE_SCALAR(bad_checkpoint
);
2705 if (bad_checkpoint
) {
2706 fatal("Restoring from checkpoints with dirty caches is not supported "
2707 "in the classic memory system. Please remove any caches or "
2708 " drain them properly before taking checkpoints.\n");
2719 Cache::CpuSidePort::getAddrRanges() const
2721 return cache
->getAddrRanges();
2725 Cache::CpuSidePort::tryTiming(PacketPtr pkt
)
2727 assert(!cache
->system
->bypassCaches());
2729 // always let express snoop packets through if even if blocked
2730 if (pkt
->isExpressSnoop()) {
2732 } else if (isBlocked() || mustSendRetry
) {
2733 // either already committed to send a retry, or blocked
2734 mustSendRetry
= true;
2737 mustSendRetry
= false;
2742 Cache::CpuSidePort::recvTimingReq(PacketPtr pkt
)
2744 assert(!cache
->system
->bypassCaches());
2746 // always let express snoop packets through if even if blocked
2747 if (pkt
->isExpressSnoop()) {
2748 bool M5_VAR_USED bypass_success
= cache
->recvTimingReq(pkt
);
2749 assert(bypass_success
);
2753 return tryTiming(pkt
) && cache
->recvTimingReq(pkt
);
2757 Cache::CpuSidePort::recvAtomic(PacketPtr pkt
)
2759 return cache
->recvAtomic(pkt
);
2763 Cache::CpuSidePort::recvFunctional(PacketPtr pkt
)
2765 // functional request
2766 cache
->functionalAccess(pkt
, true);
2770 CpuSidePort::CpuSidePort(const std::string
&_name
, Cache
*_cache
,
2771 const std::string
&_label
)
2772 : BaseCache::CacheSlavePort(_name
, _cache
, _label
), cache(_cache
)
2777 CacheParams::create()
2781 return new Cache(this);
2790 Cache::MemSidePort::recvTimingResp(PacketPtr pkt
)
2792 cache
->recvTimingResp(pkt
);
2796 // Express snooping requests to memside port
2798 Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt
)
2800 // handle snooping requests
2801 cache
->recvTimingSnoopReq(pkt
);
2805 Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt
)
2807 return cache
->recvAtomicSnoop(pkt
);
2811 Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt
)
2813 // functional snoop (note that in contrast to atomic we don't have
2814 // a specific functionalSnoop method, as they have the same
2815 // behaviour regardless)
2816 cache
->functionalAccess(pkt
, false);
2820 Cache::CacheReqPacketQueue::sendDeferredPacket()
2823 assert(!waitingOnRetry
);
2825 // there should never be any deferred request packets in the
2826 // queue, instead we resly on the cache to provide the packets
2827 // from the MSHR queue or write queue
2828 assert(deferredPacketReadyTime() == MaxTick
);
2830 // check for request packets (requests & writebacks)
2831 QueueEntry
* entry
= cache
.getNextQueueEntry();
2834 // can happen if e.g. we attempt a writeback and fail, but
2835 // before the retry, the writeback is eliminated because
2836 // we snoop another cache's ReadEx.
2838 // let our snoop responses go first if there are responses to
2839 // the same addresses
2840 if (checkConflictingSnoop(entry
->blkAddr
)) {
2843 waitingOnRetry
= entry
->sendPacket(cache
);
2846 // if we succeeded and are not waiting for a retry, schedule the
2847 // next send considering when the next queue is ready, note that
2848 // snoop responses have their own packet queue and thus schedule
2850 if (!waitingOnRetry
) {
2851 schedSendEvent(cache
.nextQueueReadyTime());
2856 MemSidePort::MemSidePort(const std::string
&_name
, Cache
*_cache
,
2857 const std::string
&_label
)
2858 : BaseCache::CacheMasterPort(_name
, _cache
, _reqQueue
, _snoopRespQueue
),
2859 _reqQueue(*_cache
, *this, _snoopRespQueue
, _label
),
2860 _snoopRespQueue(*_cache
, *this, _label
), cache(_cache
)