2 * Copyright (c) 2010-2018 ARM Limited
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010,2015 Advanced Micro Devices, Inc.
16 * All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 * Authors: Erik Hallnor
55 #include "mem/cache/cache.hh"
57 #include "base/logging.hh"
58 #include "base/types.hh"
59 #include "debug/Cache.hh"
60 #include "debug/CachePort.hh"
61 #include "debug/CacheTags.hh"
62 #include "debug/CacheVerbose.hh"
63 #include "mem/cache/blk.hh"
64 #include "mem/cache/mshr.hh"
65 #include "mem/cache/prefetch/base.hh"
66 #include "sim/sim_exit.hh"
68 Cache::Cache(const CacheParams
*p
)
69 : BaseCache(p
, p
->system
->cacheLineSize()),
71 prefetcher(p
->prefetcher
),
73 prefetchOnAccess(p
->prefetch_on_access
),
74 clusivity(p
->clusivity
),
75 writebackClean(p
->writeback_clean
),
76 tempBlockWriteback(nullptr),
77 writebackTempBlockAtomicEvent([this]{ writebackTempBlockAtomic(); },
79 EventBase::Delayed_Writeback_Pri
)
81 tempBlock
= new CacheBlk();
82 tempBlock
->data
= new uint8_t[blkSize
];
84 cpuSidePort
= new CpuSidePort(p
->name
+ ".cpu_side", this,
86 memSidePort
= new MemSidePort(p
->name
+ ".mem_side", this,
91 prefetcher
->setCache(this);
96 delete [] tempBlock
->data
;
106 BaseCache::regStats();
110 Cache::cmpAndSwap(CacheBlk
*blk
, PacketPtr pkt
)
112 assert(pkt
->isRequest());
114 uint64_t overwrite_val
;
116 uint64_t condition_val64
;
117 uint32_t condition_val32
;
119 int offset
= tags
->extractBlkOffset(pkt
->getAddr());
120 uint8_t *blk_data
= blk
->data
+ offset
;
122 assert(sizeof(uint64_t) >= pkt
->getSize());
124 overwrite_mem
= true;
125 // keep a copy of our possible write value, and copy what is at the
126 // memory address into the packet
127 pkt
->writeData((uint8_t *)&overwrite_val
);
128 pkt
->setData(blk_data
);
130 if (pkt
->req
->isCondSwap()) {
131 if (pkt
->getSize() == sizeof(uint64_t)) {
132 condition_val64
= pkt
->req
->getExtraData();
133 overwrite_mem
= !std::memcmp(&condition_val64
, blk_data
,
135 } else if (pkt
->getSize() == sizeof(uint32_t)) {
136 condition_val32
= (uint32_t)pkt
->req
->getExtraData();
137 overwrite_mem
= !std::memcmp(&condition_val32
, blk_data
,
140 panic("Invalid size for conditional read/write\n");
144 std::memcpy(blk_data
, &overwrite_val
, pkt
->getSize());
145 blk
->status
|= BlkDirty
;
151 Cache::satisfyRequest(PacketPtr pkt
, CacheBlk
*blk
,
152 bool deferred_response
, bool pending_downgrade
)
154 assert(pkt
->isRequest());
156 assert(blk
&& blk
->isValid());
157 // Occasionally this is not true... if we are a lower-level cache
158 // satisfying a string of Read and ReadEx requests from
159 // upper-level caches, a Read will mark the block as shared but we
160 // can satisfy a following ReadEx anyway since we can rely on the
161 // Read requester(s) to have buffered the ReadEx snoop and to
162 // invalidate their blocks after receiving them.
163 // assert(!pkt->needsWritable() || blk->isWritable());
164 assert(pkt
->getOffset(blkSize
) + pkt
->getSize() <= blkSize
);
166 // Check RMW operations first since both isRead() and
167 // isWrite() will be true for them
168 if (pkt
->cmd
== MemCmd::SwapReq
) {
169 cmpAndSwap(blk
, pkt
);
170 } else if (pkt
->isWrite()) {
171 // we have the block in a writable state and can go ahead,
172 // note that the line may be also be considered writable in
173 // downstream caches along the path to memory, but always
174 // Exclusive, and never Modified
175 assert(blk
->isWritable());
176 // Write or WriteLine at the first cache with block in writable state
177 if (blk
->checkWrite(pkt
)) {
178 pkt
->writeDataToBlock(blk
->data
, blkSize
);
180 // Always mark the line as dirty (and thus transition to the
181 // Modified state) even if we are a failed StoreCond so we
182 // supply data to any snoops that have appended themselves to
183 // this cache before knowing the store will fail.
184 blk
->status
|= BlkDirty
;
185 DPRINTF(CacheVerbose
, "%s for %s (write)\n", __func__
, pkt
->print());
186 } else if (pkt
->isRead()) {
188 blk
->trackLoadLocked(pkt
);
191 // all read responses have a data payload
192 assert(pkt
->hasRespData());
193 pkt
->setDataFromBlock(blk
->data
, blkSize
);
195 // determine if this read is from a (coherent) cache or not
196 if (pkt
->fromCache()) {
197 assert(pkt
->getSize() == blkSize
);
198 // special handling for coherent block requests from
199 // upper-level caches
200 if (pkt
->needsWritable()) {
202 assert(pkt
->cmd
== MemCmd::ReadExReq
||
203 pkt
->cmd
== MemCmd::SCUpgradeFailReq
);
204 assert(!pkt
->hasSharers());
206 // if we have a dirty copy, make sure the recipient
207 // keeps it marked dirty (in the modified state)
208 if (blk
->isDirty()) {
209 pkt
->setCacheResponding();
210 blk
->status
&= ~BlkDirty
;
212 } else if (blk
->isWritable() && !pending_downgrade
&&
213 !pkt
->hasSharers() &&
214 pkt
->cmd
!= MemCmd::ReadCleanReq
) {
215 // we can give the requester a writable copy on a read
217 // - we have a writable copy at this level (& below)
218 // - we don't have a pending snoop from below
219 // signaling another read request
220 // - no other cache above has a copy (otherwise it
221 // would have set hasSharers flag when
222 // snooping the packet)
223 // - the read has explicitly asked for a clean
225 if (blk
->isDirty()) {
226 // special considerations if we're owner:
227 if (!deferred_response
) {
228 // respond with the line in Modified state
229 // (cacheResponding set, hasSharers not set)
230 pkt
->setCacheResponding();
232 // if this cache is mostly inclusive, we
233 // keep the block in the Exclusive state,
234 // and pass it upwards as Modified
235 // (writable and dirty), hence we have
236 // multiple caches, all on the same path
237 // towards memory, all considering the
238 // same block writable, but only one
239 // considering it Modified
241 // we get away with multiple caches (on
242 // the same path to memory) considering
243 // the block writeable as we always enter
244 // the cache hierarchy through a cache,
245 // and first snoop upwards in all other
247 blk
->status
&= ~BlkDirty
;
249 // if we're responding after our own miss,
250 // there's a window where the recipient didn't
251 // know it was getting ownership and may not
252 // have responded to snoops correctly, so we
253 // have to respond with a shared line
254 pkt
->setHasSharers();
258 // otherwise only respond with a shared copy
259 pkt
->setHasSharers();
262 } else if (pkt
->isUpgrade()) {
264 assert(!pkt
->hasSharers());
266 if (blk
->isDirty()) {
267 // we were in the Owned state, and a cache above us that
268 // has the line in Shared state needs to be made aware
269 // that the data it already has is in fact dirty
270 pkt
->setCacheResponding();
271 blk
->status
&= ~BlkDirty
;
274 assert(pkt
->isInvalidate());
275 invalidateBlock(blk
);
276 DPRINTF(CacheVerbose
, "%s for %s (invalidation)\n", __func__
,
281 /////////////////////////////////////////////////////
283 // Access path: requests coming in from the CPU side
285 /////////////////////////////////////////////////////
288 Cache::access(PacketPtr pkt
, CacheBlk
*&blk
, Cycles
&lat
,
289 PacketList
&writebacks
)
292 assert(pkt
->isRequest());
294 chatty_assert(!(isReadOnly
&& pkt
->isWrite()),
295 "Should never see a write in a read-only cache %s\n",
298 DPRINTF(CacheVerbose
, "%s for %s\n", __func__
, pkt
->print());
300 if (pkt
->req
->isUncacheable()) {
301 DPRINTF(Cache
, "uncacheable: %s\n", pkt
->print());
303 // flush and invalidate any existing block
304 CacheBlk
*old_blk(tags
->findBlock(pkt
->getAddr(), pkt
->isSecure()));
305 if (old_blk
&& old_blk
->isValid()) {
306 if (old_blk
->isDirty() || writebackClean
)
307 writebacks
.push_back(writebackBlk(old_blk
));
309 writebacks
.push_back(cleanEvictBlk(old_blk
));
310 invalidateBlock(old_blk
);
314 // lookupLatency is the latency in case the request is uncacheable.
319 // Here lat is the value passed as parameter to accessBlock() function
320 // that can modify its value.
321 blk
= tags
->accessBlock(pkt
->getAddr(), pkt
->isSecure(), lat
);
323 DPRINTF(Cache
, "%s %s\n", pkt
->print(),
324 blk
? "hit " + blk
->print() : "miss");
326 if (pkt
->req
->isCacheMaintenance()) {
327 // A cache maintenance operation is always forwarded to the
328 // memory below even if the block is found in dirty state.
330 // We defer any changes to the state of the block until we
331 // create and mark as in service the mshr for the downstream
336 if (pkt
->isEviction()) {
337 // We check for presence of block in above caches before issuing
338 // Writeback or CleanEvict to write buffer. Therefore the only
339 // possible cases can be of a CleanEvict packet coming from above
340 // encountering a Writeback generated in this cache peer cache and
341 // waiting in the write buffer. Cases of upper level peer caches
342 // generating CleanEvict and Writeback or simply CleanEvict and
343 // CleanEvict almost simultaneously will be caught by snoops sent out
345 WriteQueueEntry
*wb_entry
= writeBuffer
.findMatch(pkt
->getAddr(),
348 assert(wb_entry
->getNumTargets() == 1);
349 PacketPtr wbPkt
= wb_entry
->getTarget()->pkt
;
350 assert(wbPkt
->isWriteback());
352 if (pkt
->isCleanEviction()) {
353 // The CleanEvict and WritebackClean snoops into other
354 // peer caches of the same level while traversing the
355 // crossbar. If a copy of the block is found, the
356 // packet is deleted in the crossbar. Hence, none of
357 // the other upper level caches connected to this
358 // cache have the block, so we can clear the
359 // BLOCK_CACHED flag in the Writeback if set and
360 // discard the CleanEvict by returning true.
361 wbPkt
->clearBlockCached();
364 assert(pkt
->cmd
== MemCmd::WritebackDirty
);
365 // Dirty writeback from above trumps our clean
366 // writeback... discard here
367 // Note: markInService will remove entry from writeback buffer.
368 markInService(wb_entry
);
374 // Writeback handling is special case. We can write the block into
375 // the cache without having a writeable copy (or any copy at all).
376 if (pkt
->isWriteback()) {
377 assert(blkSize
== pkt
->getSize());
379 // we could get a clean writeback while we are having
380 // outstanding accesses to a block, do the simple thing for
381 // now and drop the clean writeback so that we do not upset
382 // any ordering/decisions about ownership already taken
383 if (pkt
->cmd
== MemCmd::WritebackClean
&&
384 mshrQueue
.findMatch(pkt
->getAddr(), pkt
->isSecure())) {
385 DPRINTF(Cache
, "Clean writeback %#llx to block with MSHR, "
386 "dropping\n", pkt
->getAddr());
390 if (blk
== nullptr) {
391 // need to do a replacement
392 blk
= allocateBlock(pkt
->getAddr(), pkt
->isSecure(), writebacks
);
393 if (blk
== nullptr) {
394 // no replaceable block available: give up, fwd to next level.
398 tags
->insertBlock(pkt
, blk
);
400 blk
->status
= (BlkValid
| BlkReadable
);
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 assert(!blk
->isDirty());
409 blk
->status
|= BlkDirty
;
411 // if the packet does not have sharers, it is passing
412 // writable, and we got the writeback in Modified or Exclusive
413 // state, if not we are in the Owned or Shared state
414 if (!pkt
->hasSharers()) {
415 blk
->status
|= BlkWritable
;
417 // nothing else to do; writeback doesn't expect response
418 assert(!pkt
->needsResponse());
419 std::memcpy(blk
->data
, pkt
->getConstPtr
<uint8_t>(), blkSize
);
420 DPRINTF(Cache
, "%s new state is %s\n", __func__
, blk
->print());
422 // populate the time when the block will be ready to access.
423 blk
->whenReady
= clockEdge(fillLatency
) + pkt
->headerDelay
+
426 } else if (pkt
->cmd
== MemCmd::CleanEvict
) {
427 if (blk
!= nullptr) {
428 // Found the block in the tags, need to stop CleanEvict from
429 // propagating further down the hierarchy. Returning true will
430 // treat the CleanEvict like a satisfied write request and delete
434 // We didn't find the block here, propagate the CleanEvict further
435 // down the memory hierarchy. Returning false will treat the CleanEvict
436 // like a Writeback which could not find a replaceable block so has to
439 } else if (pkt
->cmd
== MemCmd::WriteClean
) {
440 // WriteClean handling is a special case. We can allocate a
441 // block directly if it doesn't exist and we can update the
442 // block immediately. The WriteClean transfers the ownership
443 // of the block as well.
444 assert(blkSize
== pkt
->getSize());
447 if (pkt
->writeThrough()) {
448 // if this is a write through packet, we don't try to
449 // allocate if the block is not present
452 // a writeback that misses needs to allocate a new block
453 blk
= allocateBlock(pkt
->getAddr(), pkt
->isSecure(),
456 // no replaceable block available: give up, fwd to
461 tags
->insertBlock(pkt
, blk
);
463 blk
->status
= (BlkValid
| BlkReadable
);
464 if (pkt
->isSecure()) {
465 blk
->status
|= BlkSecure
;
470 // at this point either this is a writeback or a write-through
471 // write clean operation and the block is already in this
472 // cache, we need to update the data and the block flags
474 assert(!blk
->isDirty());
475 if (!pkt
->writeThrough()) {
476 blk
->status
|= BlkDirty
;
478 // nothing else to do; writeback doesn't expect response
479 assert(!pkt
->needsResponse());
480 std::memcpy(blk
->data
, pkt
->getConstPtr
<uint8_t>(), blkSize
);
481 DPRINTF(Cache
, "%s new state is %s\n", __func__
, blk
->print());
484 // populate the time when the block will be ready to access.
485 blk
->whenReady
= clockEdge(fillLatency
) + pkt
->headerDelay
+
487 // if this a write-through packet it will be sent to cache
489 return !pkt
->writeThrough();
490 } else if (blk
&& (pkt
->needsWritable() ? blk
->isWritable() :
491 blk
->isReadable())) {
492 // OK to satisfy access
494 satisfyRequest(pkt
, blk
);
495 maintainClusivity(pkt
->fromCache(), blk
);
500 // Can't satisfy access normally... either no block (blk == nullptr)
501 // or have block but need writable
505 if (blk
== nullptr && pkt
->isLLSC() && pkt
->isWrite()) {
506 // complete miss on store conditional... just give up now
507 pkt
->req
->setExtraData(0);
515 Cache::maintainClusivity(bool from_cache
, CacheBlk
*blk
)
517 if (from_cache
&& blk
&& blk
->isValid() && !blk
->isDirty() &&
518 clusivity
== Enums::mostly_excl
) {
519 // if we have responded to a cache, and our block is still
520 // valid, but not dirty, and this cache is mostly exclusive
521 // with respect to the cache above, drop the block
522 invalidateBlock(blk
);
527 Cache::doWritebacks(PacketList
& writebacks
, Tick forward_time
)
529 while (!writebacks
.empty()) {
530 PacketPtr wbPkt
= writebacks
.front();
531 // We use forwardLatency here because we are copying writebacks to
534 // Call isCachedAbove for Writebacks, CleanEvicts and
535 // WriteCleans to discover if the block is cached above.
536 if (isCachedAbove(wbPkt
)) {
537 if (wbPkt
->cmd
== MemCmd::CleanEvict
) {
538 // Delete CleanEvict because cached copies exist above. The
539 // packet destructor will delete the request object because
540 // this is a non-snoop request packet which does not require a
543 } else if (wbPkt
->cmd
== MemCmd::WritebackClean
) {
544 // clean writeback, do not send since the block is
545 // still cached above
546 assert(writebackClean
);
549 assert(wbPkt
->cmd
== MemCmd::WritebackDirty
||
550 wbPkt
->cmd
== MemCmd::WriteClean
);
551 // Set BLOCK_CACHED flag in Writeback and send below, so that
552 // the Writeback does not reset the bit corresponding to this
553 // address in the snoop filter below.
554 wbPkt
->setBlockCached();
555 allocateWriteBuffer(wbPkt
, forward_time
);
558 // If the block is not cached above, send packet below. Both
559 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
560 // reset the bit corresponding to this address in the snoop filter
562 allocateWriteBuffer(wbPkt
, forward_time
);
564 writebacks
.pop_front();
569 Cache::doWritebacksAtomic(PacketList
& writebacks
)
571 while (!writebacks
.empty()) {
572 PacketPtr wbPkt
= writebacks
.front();
573 // Call isCachedAbove for both Writebacks and CleanEvicts. If
574 // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
575 // and discard CleanEvicts.
576 if (isCachedAbove(wbPkt
, false)) {
577 if (wbPkt
->cmd
== MemCmd::WritebackDirty
||
578 wbPkt
->cmd
== MemCmd::WriteClean
) {
579 // Set BLOCK_CACHED flag in Writeback and send below,
580 // so that the Writeback does not reset the bit
581 // corresponding to this address in the snoop filter
582 // below. We can discard CleanEvicts because cached
583 // copies exist above. Atomic mode isCachedAbove
584 // modifies packet to set BLOCK_CACHED flag
585 memSidePort
->sendAtomic(wbPkt
);
588 // If the block is not cached above, send packet below. Both
589 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
590 // reset the bit corresponding to this address in the snoop filter
592 memSidePort
->sendAtomic(wbPkt
);
594 writebacks
.pop_front();
595 // In case of CleanEvicts, the packet destructor will delete the
596 // request object because this is a non-snoop request packet which
597 // does not require a response.
604 Cache::recvTimingSnoopResp(PacketPtr pkt
)
606 DPRINTF(Cache
, "%s for %s\n", __func__
, pkt
->print());
608 assert(pkt
->isResponse());
609 assert(!system
->bypassCaches());
611 // determine if the response is from a snoop request we created
612 // (in which case it should be in the outstandingSnoop), or if we
613 // merely forwarded someone else's snoop request
614 const bool forwardAsSnoop
= outstandingSnoop
.find(pkt
->req
) ==
615 outstandingSnoop
.end();
617 if (!forwardAsSnoop
) {
618 // the packet came from this cache, so sink it here and do not
620 assert(pkt
->cmd
== MemCmd::HardPFResp
);
622 outstandingSnoop
.erase(pkt
->req
);
624 DPRINTF(Cache
, "Got prefetch response from above for addr "
625 "%#llx (%s)\n", pkt
->getAddr(), pkt
->isSecure() ? "s" : "ns");
630 // forwardLatency is set here because there is a response from an
631 // upper level cache.
632 // To pay the delay that occurs if the packet comes from the bus,
633 // we charge also headerDelay.
634 Tick snoop_resp_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
635 // Reset the timing of the packet.
636 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
637 memSidePort
->schedTimingSnoopResp(pkt
, snoop_resp_time
);
641 Cache::promoteWholeLineWrites(PacketPtr pkt
)
643 // Cache line clearing instructions
644 if (doFastWrites
&& (pkt
->cmd
== MemCmd::WriteReq
) &&
645 (pkt
->getSize() == blkSize
) && (pkt
->getOffset(blkSize
) == 0)) {
646 pkt
->cmd
= MemCmd::WriteLineReq
;
647 DPRINTF(Cache
, "packet promoted from Write to WriteLineReq\n");
652 Cache::recvTimingReq(PacketPtr pkt
)
654 DPRINTF(CacheTags
, "%s tags:\n%s\n", __func__
, tags
->print());
656 assert(pkt
->isRequest());
658 // Just forward the packet if caches are disabled.
659 if (system
->bypassCaches()) {
660 // @todo This should really enqueue the packet rather
661 bool M5_VAR_USED success
= memSidePort
->sendTimingReq(pkt
);
666 promoteWholeLineWrites(pkt
);
668 // Cache maintenance operations have to visit all the caches down
669 // to the specified xbar (PoC, PoU, etc.). Even if a cache above
670 // is responding we forward the packet to the memory below rather
671 // than creating an express snoop.
672 if (pkt
->cacheResponding()) {
673 // a cache above us (but not where the packet came from) is
674 // responding to the request, in other words it has the line
675 // in Modified or Owned state
676 DPRINTF(Cache
, "Cache above responding to %s: not responding\n",
679 // if the packet needs the block to be writable, and the cache
680 // that has promised to respond (setting the cache responding
681 // flag) is not providing writable (it is in Owned rather than
682 // the Modified state), we know that there may be other Shared
683 // copies in the system; go out and invalidate them all
684 assert(pkt
->needsWritable() && !pkt
->responderHadWritable());
686 // an upstream cache that had the line in Owned state
687 // (dirty, but not writable), is responding and thus
688 // transferring the dirty line from one branch of the
689 // cache hierarchy to another
691 // send out an express snoop and invalidate all other
692 // copies (snooping a packet that needs writable is the
693 // same as an invalidation), thus turning the Owned line
694 // into a Modified line, note that we don't invalidate the
695 // block in the current cache or any other cache on the
698 // create a downstream express snoop with cleared packet
699 // flags, there is no need to allocate any data as the
700 // packet is merely used to co-ordinate state transitions
701 Packet
*snoop_pkt
= new Packet(pkt
, true, false);
703 // also reset the bus time that the original packet has
705 snoop_pkt
->headerDelay
= snoop_pkt
->payloadDelay
= 0;
707 // make this an instantaneous express snoop, and let the
708 // other caches in the system know that the another cache
709 // is responding, because we have found the authorative
710 // copy (Modified or Owned) that will supply the right
712 snoop_pkt
->setExpressSnoop();
713 snoop_pkt
->setCacheResponding();
715 // this express snoop travels towards the memory, and at
716 // every crossbar it is snooped upwards thus reaching
717 // every cache in the system
718 bool M5_VAR_USED success
= memSidePort
->sendTimingReq(snoop_pkt
);
719 // express snoops always succeed
722 // main memory will delete the snoop packet
724 // queue for deletion, as opposed to immediate deletion, as
725 // the sending cache is still relying on the packet
726 pendingDelete
.reset(pkt
);
728 // no need to take any further action in this particular cache
729 // as an upstram cache has already committed to responding,
730 // and we have already sent out any express snoops in the
731 // section above to ensure all other copies in the system are
736 // anything that is merely forwarded pays for the forward latency and
737 // the delay provided by the crossbar
738 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
740 // We use lookupLatency here because it is used to specify the latency
742 Cycles lat
= lookupLatency
;
743 CacheBlk
*blk
= nullptr;
744 bool satisfied
= false;
746 PacketList writebacks
;
747 // Note that lat is passed by reference here. The function
748 // access() calls accessBlock() which can modify lat value.
749 satisfied
= access(pkt
, blk
, lat
, writebacks
);
751 // copy writebacks to write buffer here to ensure they logically
752 // proceed anything happening below
753 doWritebacks(writebacks
, forward_time
);
756 // Here we charge the headerDelay that takes into account the latencies
757 // of the bus, if the packet comes from it.
758 // The latency charged it is just lat that is the value of lookupLatency
759 // modified by access() function, or if not just lookupLatency.
760 // In case of a hit we are neglecting response latency.
761 // In case of a miss we are neglecting forward latency.
762 Tick request_time
= clockEdge(lat
) + pkt
->headerDelay
;
763 // Here we reset the timing of the packet.
764 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
766 // track time of availability of next prefetch, if any
767 Tick next_pf_time
= MaxTick
;
769 bool needsResponse
= pkt
->needsResponse();
772 // should never be satisfying an uncacheable access as we
773 // flush and invalidate any existing block as part of the
775 assert(!pkt
->req
->isUncacheable());
777 // hit (for all other request types)
779 if (prefetcher
&& (prefetchOnAccess
||
780 (blk
&& blk
->wasPrefetched()))) {
782 blk
->status
&= ~BlkHWPrefetched
;
784 // Don't notify on SWPrefetch
785 if (!pkt
->cmd
.isSWPrefetch()) {
786 assert(!pkt
->req
->isCacheMaintenance());
787 next_pf_time
= prefetcher
->notify(pkt
);
792 pkt
->makeTimingResponse();
793 // @todo: Make someone pay for this
794 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
796 // In this case we are considering request_time that takes
797 // into account the delay of the xbar, if any, and just
798 // lat, neglecting responseLatency, modelling hit latency
799 // just as lookupLatency or or the value of lat overriden
800 // by access(), that calls accessBlock() function.
801 cpuSidePort
->schedTimingResp(pkt
, request_time
, true);
803 DPRINTF(Cache
, "%s satisfied %s, no response needed\n", __func__
,
806 // queue the packet for deletion, as the sending cache is
807 // still relying on it; if the block is found in access(),
808 // CleanEvict and Writeback messages will be deleted
810 pendingDelete
.reset(pkt
);
815 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
817 // ignore any existing MSHR if we are dealing with an
818 // uncacheable request
819 MSHR
*mshr
= pkt
->req
->isUncacheable() ? nullptr :
820 mshrQueue
.findMatch(blk_addr
, pkt
->isSecure());
822 // Software prefetch handling:
823 // To keep the core from waiting on data it won't look at
824 // anyway, send back a response with dummy data. Miss handling
825 // will continue asynchronously. Unfortunately, the core will
826 // insist upon freeing original Packet/Request, so we have to
827 // create a new pair with a different lifecycle. Note that this
828 // processing happens before any MSHR munging on the behalf of
829 // this request because this new Request will be the one stored
830 // into the MSHRs, not the original.
831 if (pkt
->cmd
.isSWPrefetch()) {
832 assert(needsResponse
);
833 assert(pkt
->req
->hasPaddr());
834 assert(!pkt
->req
->isUncacheable());
836 // There's no reason to add a prefetch as an additional target
837 // to an existing MSHR. If an outstanding request is already
838 // in progress, there is nothing for the prefetch to do.
839 // If this is the case, we don't even create a request at all.
840 PacketPtr pf
= nullptr;
843 // copy the request and create a new SoftPFReq packet
844 RequestPtr req
= new Request(pkt
->req
->getPaddr(),
846 pkt
->req
->getFlags(),
847 pkt
->req
->masterId());
848 pf
= new Packet(req
, pkt
->cmd
);
850 assert(pf
->getAddr() == pkt
->getAddr());
851 assert(pf
->getSize() == pkt
->getSize());
854 pkt
->makeTimingResponse();
856 // request_time is used here, taking into account lat and the delay
857 // charged if the packet comes from the xbar.
858 cpuSidePort
->schedTimingResp(pkt
, request_time
, true);
860 // If an outstanding request is in progress (we found an
861 // MSHR) this is set to null
867 /// @note writebacks will be checked in getNextMSHR()
868 /// for any conflicting requests to the same block
870 //@todo remove hw_pf here
872 // Coalesce unless it was a software prefetch (see above).
874 assert(!pkt
->isWriteback());
875 // CleanEvicts corresponding to blocks which have
876 // outstanding requests in MSHRs are simply sunk here
877 if (pkt
->cmd
== MemCmd::CleanEvict
) {
878 pendingDelete
.reset(pkt
);
879 } else if (pkt
->cmd
== MemCmd::WriteClean
) {
880 // A WriteClean should never coalesce with any
881 // outstanding cache maintenance requests.
883 // We use forward_time here because there is an
884 // uncached memory write, forwarded to WriteBuffer.
885 allocateWriteBuffer(pkt
, forward_time
);
887 DPRINTF(Cache
, "%s coalescing MSHR for %s\n", __func__
,
890 assert(pkt
->req
->masterId() < system
->maxMasters());
891 mshr_hits
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
892 // We use forward_time here because it is the same
893 // considering new targets. We have multiple
894 // requests for the same address here. It
895 // specifies the latency to allocate an internal
896 // buffer and to schedule an event to the queued
897 // port and also takes into account the additional
898 // delay of the xbar.
899 mshr
->allocateTarget(pkt
, forward_time
, order
++,
900 allocOnFill(pkt
->cmd
));
901 if (mshr
->getNumTargets() == numTarget
) {
903 setBlocked(Blocked_NoTargets
);
904 // need to be careful with this... if this mshr isn't
905 // ready yet (i.e. time > curTick()), we don't want to
906 // move it ahead of mshrs that are ready
907 // mshrQueue.moveToFront(mshr);
910 // We should call the prefetcher reguardless if the request is
911 // satisfied or not, reguardless if the request is in the MSHR
912 // or not. The request could be a ReadReq hit, but still not
913 // satisfied (potentially because of a prior write to the same
914 // cache line. So, even when not satisfied, tehre is an MSHR
915 // already allocated for this, we need to let the prefetcher
916 // know about the request
918 // Don't notify on SWPrefetch
919 if (!pkt
->cmd
.isSWPrefetch() &&
920 !pkt
->req
->isCacheMaintenance())
921 next_pf_time
= prefetcher
->notify(pkt
);
926 assert(pkt
->req
->masterId() < system
->maxMasters());
927 if (pkt
->req
->isUncacheable()) {
928 mshr_uncacheable
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
930 mshr_misses
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
933 if (pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
||
934 (pkt
->req
->isUncacheable() && pkt
->isWrite())) {
935 // We use forward_time here because there is an
936 // uncached memory write, forwarded to WriteBuffer.
937 allocateWriteBuffer(pkt
, forward_time
);
939 if (blk
&& blk
->isValid()) {
940 // should have flushed and have no valid block
941 assert(!pkt
->req
->isUncacheable());
943 // If we have a write miss to a valid block, we
944 // need to mark the block non-readable. Otherwise
945 // if we allow reads while there's an outstanding
946 // write miss, the read could return stale data
947 // out of the cache block... a more aggressive
948 // system could detect the overlap (if any) and
949 // forward data out of the MSHRs, but we don't do
950 // that yet. Note that we do need to leave the
951 // block valid so that it stays in the cache, in
952 // case we get an upgrade response (and hence no
953 // new data) when the write miss completes.
954 // As long as CPUs do proper store/load forwarding
955 // internally, and have a sufficiently weak memory
956 // model, this is probably unnecessary, but at some
957 // point it must have seemed like we needed it...
958 assert((pkt
->needsWritable() && !blk
->isWritable()) ||
959 pkt
->req
->isCacheMaintenance());
960 blk
->status
&= ~BlkReadable
;
962 // Here we are using forward_time, modelling the latency of
963 // a miss (outbound) just as forwardLatency, neglecting the
964 // lookupLatency component.
965 allocateMissBuffer(pkt
, forward_time
);
969 // Don't notify on SWPrefetch
970 if (!pkt
->cmd
.isSWPrefetch() &&
971 !pkt
->req
->isCacheMaintenance())
972 next_pf_time
= prefetcher
->notify(pkt
);
977 if (next_pf_time
!= MaxTick
)
978 schedMemSideSendEvent(next_pf_time
);
984 Cache::createMissPacket(PacketPtr cpu_pkt
, CacheBlk
*blk
,
985 bool needsWritable
) const
987 // should never see evictions here
988 assert(!cpu_pkt
->isEviction());
990 bool blkValid
= blk
&& blk
->isValid();
992 if (cpu_pkt
->req
->isUncacheable() ||
993 (!blkValid
&& cpu_pkt
->isUpgrade()) ||
994 cpu_pkt
->cmd
== MemCmd::InvalidateReq
|| cpu_pkt
->isClean()) {
995 // uncacheable requests and upgrades from upper-level caches
996 // that missed completely just go through as is
1000 assert(cpu_pkt
->needsResponse());
1003 // @TODO make useUpgrades a parameter.
1004 // Note that ownership protocols require upgrade, otherwise a
1005 // write miss on a shared owned block will generate a ReadExcl,
1006 // which will clobber the owned copy.
1007 const bool useUpgrades
= true;
1008 if (cpu_pkt
->cmd
== MemCmd::WriteLineReq
) {
1009 assert(!blkValid
|| !blk
->isWritable());
1010 // forward as invalidate to all other caches, this gives us
1011 // the line in Exclusive state, and invalidates all other
1013 cmd
= MemCmd::InvalidateReq
;
1014 } else if (blkValid
&& useUpgrades
) {
1015 // only reason to be here is that blk is read only and we need
1016 // it to be writable
1017 assert(needsWritable
);
1018 assert(!blk
->isWritable());
1019 cmd
= cpu_pkt
->isLLSC() ? MemCmd::SCUpgradeReq
: MemCmd::UpgradeReq
;
1020 } else if (cpu_pkt
->cmd
== MemCmd::SCUpgradeFailReq
||
1021 cpu_pkt
->cmd
== MemCmd::StoreCondFailReq
) {
1022 // Even though this SC will fail, we still need to send out the
1023 // request and get the data to supply it to other snoopers in the case
1024 // where the determination the StoreCond fails is delayed due to
1025 // all caches not being on the same local bus.
1026 cmd
= MemCmd::SCUpgradeFailReq
;
1030 // If the request does not need a writable there are two cases
1031 // where we need to ensure the response will not fetch the
1032 // block in dirty state:
1033 // * this cache is read only and it does not perform
1035 // * this cache is mostly exclusive and will not fill (since
1036 // it does not fill it will have to writeback the dirty data
1037 // immediately which generates uneccesary writebacks).
1038 bool force_clean_rsp
= isReadOnly
|| clusivity
== Enums::mostly_excl
;
1039 cmd
= needsWritable
? MemCmd::ReadExReq
:
1040 (force_clean_rsp
? MemCmd::ReadCleanReq
: MemCmd::ReadSharedReq
);
1042 PacketPtr pkt
= new Packet(cpu_pkt
->req
, cmd
, blkSize
);
1044 // if there are upstream caches that have already marked the
1045 // packet as having sharers (not passing writable), pass that info
1047 if (cpu_pkt
->hasSharers() && !needsWritable
) {
1048 // note that cpu_pkt may have spent a considerable time in the
1049 // MSHR queue and that the information could possibly be out
1050 // of date, however, there is no harm in conservatively
1051 // assuming the block has sharers
1052 pkt
->setHasSharers();
1053 DPRINTF(Cache
, "%s: passing hasSharers from %s to %s\n",
1054 __func__
, cpu_pkt
->print(), pkt
->print());
1057 // the packet should be block aligned
1058 assert(pkt
->getAddr() == pkt
->getBlockAddr(blkSize
));
1061 DPRINTF(Cache
, "%s: created %s from %s\n", __func__
, pkt
->print(),
1068 Cache::recvAtomic(PacketPtr pkt
)
1070 // We are in atomic mode so we pay just for lookupLatency here.
1071 Cycles lat
= lookupLatency
;
1073 // Forward the request if the system is in cache bypass mode.
1074 if (system
->bypassCaches())
1075 return ticksToCycles(memSidePort
->sendAtomic(pkt
));
1077 promoteWholeLineWrites(pkt
);
1079 // follow the same flow as in recvTimingReq, and check if a cache
1080 // above us is responding
1081 if (pkt
->cacheResponding() && !pkt
->isClean()) {
1082 assert(!pkt
->req
->isCacheInvalidate());
1083 DPRINTF(Cache
, "Cache above responding to %s: not responding\n",
1086 // if a cache is responding, and it had the line in Owned
1087 // rather than Modified state, we need to invalidate any
1088 // copies that are not on the same path to memory
1089 assert(pkt
->needsWritable() && !pkt
->responderHadWritable());
1090 lat
+= ticksToCycles(memSidePort
->sendAtomic(pkt
));
1092 return lat
* clockPeriod();
1095 // should assert here that there are no outstanding MSHRs or
1096 // writebacks... that would mean that someone used an atomic
1097 // access in timing mode
1099 CacheBlk
*blk
= nullptr;
1100 PacketList writebacks
;
1101 bool satisfied
= access(pkt
, blk
, lat
, writebacks
);
1103 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
1104 // A cache clean opearation is looking for a dirty
1105 // block. If a dirty block is encountered a WriteClean
1106 // will update any copies to the path to the memory
1107 // until the point of reference.
1108 DPRINTF(CacheVerbose
, "%s: packet %s found block: %s\n",
1109 __func__
, pkt
->print(), blk
->print());
1110 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest(), pkt
->id
);
1111 writebacks
.push_back(wb_pkt
);
1112 pkt
->setSatisfied();
1115 // handle writebacks resulting from the access here to ensure they
1116 // logically proceed anything happening below
1117 doWritebacksAtomic(writebacks
);
1122 // deal with the packets that go through the write path of
1123 // the cache, i.e. any evictions and writes
1124 if (pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
||
1125 (pkt
->req
->isUncacheable() && pkt
->isWrite())) {
1126 lat
+= ticksToCycles(memSidePort
->sendAtomic(pkt
));
1127 return lat
* clockPeriod();
1131 PacketPtr bus_pkt
= createMissPacket(pkt
, blk
, pkt
->needsWritable());
1133 bool is_forward
= (bus_pkt
== nullptr);
1136 // just forwarding the same request to the next level
1137 // no local cache operation involved
1141 DPRINTF(Cache
, "%s: Sending an atomic %s\n", __func__
,
1145 CacheBlk::State old_state
= blk
? blk
->status
: 0;
1148 lat
+= ticksToCycles(memSidePort
->sendAtomic(bus_pkt
));
1150 bool is_invalidate
= bus_pkt
->isInvalidate();
1152 // We are now dealing with the response handling
1153 DPRINTF(Cache
, "%s: Receive response: %s in state %i\n", __func__
,
1154 bus_pkt
->print(), old_state
);
1156 // If packet was a forward, the response (if any) is already
1157 // in place in the bus_pkt == pkt structure, so we don't need
1158 // to do anything. Otherwise, use the separate bus_pkt to
1159 // generate response to pkt and then delete it.
1161 if (pkt
->needsResponse()) {
1162 assert(bus_pkt
->isResponse());
1163 if (bus_pkt
->isError()) {
1164 pkt
->makeAtomicResponse();
1165 pkt
->copyError(bus_pkt
);
1166 } else if (pkt
->cmd
== MemCmd::WriteLineReq
) {
1167 // note the use of pkt, not bus_pkt here.
1169 // write-line request to the cache that promoted
1170 // the write to a whole line
1171 blk
= handleFill(pkt
, blk
, writebacks
,
1172 allocOnFill(pkt
->cmd
));
1173 assert(blk
!= NULL
);
1174 is_invalidate
= false;
1175 satisfyRequest(pkt
, blk
);
1176 } else if (bus_pkt
->isRead() ||
1177 bus_pkt
->cmd
== MemCmd::UpgradeResp
) {
1178 // we're updating cache state to allow us to
1179 // satisfy the upstream request from the cache
1180 blk
= handleFill(bus_pkt
, blk
, writebacks
,
1181 allocOnFill(pkt
->cmd
));
1182 satisfyRequest(pkt
, blk
);
1183 maintainClusivity(pkt
->fromCache(), blk
);
1185 // we're satisfying the upstream request without
1186 // modifying cache state, e.g., a write-through
1187 pkt
->makeAtomicResponse();
1193 if (is_invalidate
&& blk
&& blk
->isValid()) {
1194 invalidateBlock(blk
);
1198 // Note that we don't invoke the prefetcher at all in atomic mode.
1199 // It's not clear how to do it properly, particularly for
1200 // prefetchers that aggressively generate prefetch candidates and
1201 // rely on bandwidth contention to throttle them; these will tend
1202 // to pollute the cache in atomic mode since there is no bandwidth
1203 // contention. If we ever do want to enable prefetching in atomic
1204 // mode, though, this is the place to do it... see timingAccess()
1205 // for an example (though we'd want to issue the prefetch(es)
1206 // immediately rather than calling requestMemSideBus() as we do
1209 // do any writebacks resulting from the response handling
1210 doWritebacksAtomic(writebacks
);
1212 // if we used temp block, check to see if its valid and if so
1213 // clear it out, but only do so after the call to recvAtomic is
1214 // finished so that any downstream observers (such as a snoop
1215 // filter), first see the fill, and only then see the eviction
1216 if (blk
== tempBlock
&& tempBlock
->isValid()) {
1217 // the atomic CPU calls recvAtomic for fetch and load/store
1218 // sequentuially, and we may already have a tempBlock
1219 // writeback from the fetch that we have not yet sent
1220 if (tempBlockWriteback
) {
1221 // if that is the case, write the prevoius one back, and
1222 // do not schedule any new event
1223 writebackTempBlockAtomic();
1225 // the writeback/clean eviction happens after the call to
1226 // recvAtomic has finished (but before any successive
1227 // calls), so that the response handling from the fill is
1228 // allowed to happen first
1229 schedule(writebackTempBlockAtomicEvent
, curTick());
1232 tempBlockWriteback
= (blk
->isDirty() || writebackClean
) ?
1233 writebackBlk(blk
) : cleanEvictBlk(blk
);
1234 invalidateBlock(blk
);
1237 if (pkt
->needsResponse()) {
1238 pkt
->makeAtomicResponse();
1241 return lat
* clockPeriod();
1246 Cache::functionalAccess(PacketPtr pkt
, bool fromCpuSide
)
1248 if (system
->bypassCaches()) {
1249 // Packets from the memory side are snoop request and
1250 // shouldn't happen in bypass mode.
1251 assert(fromCpuSide
);
1253 // The cache should be flushed if we are in cache bypass mode,
1254 // so we don't need to check if we need to update anything.
1255 memSidePort
->sendFunctional(pkt
);
1259 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
1260 bool is_secure
= pkt
->isSecure();
1261 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), is_secure
);
1262 MSHR
*mshr
= mshrQueue
.findMatch(blk_addr
, is_secure
);
1264 pkt
->pushLabel(name());
1266 CacheBlkPrintWrapper
cbpw(blk
);
1268 // Note that just because an L2/L3 has valid data doesn't mean an
1269 // L1 doesn't have a more up-to-date modified copy that still
1270 // needs to be found. As a result we always update the request if
1271 // we have it, but only declare it satisfied if we are the owner.
1273 // see if we have data at all (owned or otherwise)
1274 bool have_data
= blk
&& blk
->isValid()
1275 && pkt
->checkFunctional(&cbpw
, blk_addr
, is_secure
, blkSize
,
1278 // data we have is dirty if marked as such or if we have an
1279 // in-service MSHR that is pending a modified line
1281 have_data
&& (blk
->isDirty() ||
1282 (mshr
&& mshr
->inService
&& mshr
->isPendingModified()));
1284 bool done
= have_dirty
1285 || cpuSidePort
->checkFunctional(pkt
)
1286 || mshrQueue
.checkFunctional(pkt
, blk_addr
)
1287 || writeBuffer
.checkFunctional(pkt
, blk_addr
)
1288 || memSidePort
->checkFunctional(pkt
);
1290 DPRINTF(CacheVerbose
, "%s: %s %s%s%s\n", __func__
, pkt
->print(),
1291 (blk
&& blk
->isValid()) ? "valid " : "",
1292 have_data
? "data " : "", done
? "done " : "");
1294 // We're leaving the cache, so pop cache->name() label
1298 pkt
->makeResponse();
1300 // if it came as a request from the CPU side then make sure it
1301 // continues towards the memory side
1303 memSidePort
->sendFunctional(pkt
);
1304 } else if (cpuSidePort
->isSnooping()) {
1305 // if it came from the memory side, it must be a snoop request
1306 // and we should only forward it if we are forwarding snoops
1307 cpuSidePort
->sendFunctionalSnoop(pkt
);
1313 /////////////////////////////////////////////////////
1315 // Response handling: responses from the memory side
1317 /////////////////////////////////////////////////////
1321 Cache::handleUncacheableWriteResp(PacketPtr pkt
)
1323 Tick completion_time
= clockEdge(responseLatency
) +
1324 pkt
->headerDelay
+ pkt
->payloadDelay
;
1326 // Reset the bus additional time as it is now accounted for
1327 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
1329 cpuSidePort
->schedTimingResp(pkt
, completion_time
, true);
1333 Cache::recvTimingResp(PacketPtr pkt
)
1335 assert(pkt
->isResponse());
1337 // all header delay should be paid for by the crossbar, unless
1338 // this is a prefetch response from above
1339 panic_if(pkt
->headerDelay
!= 0 && pkt
->cmd
!= MemCmd::HardPFResp
,
1340 "%s saw a non-zero packet delay\n", name());
1342 bool is_error
= pkt
->isError();
1345 DPRINTF(Cache
, "%s: Cache received %s with error\n", __func__
,
1349 DPRINTF(Cache
, "%s: Handling response %s\n", __func__
,
1352 // if this is a write, we should be looking at an uncacheable
1354 if (pkt
->isWrite()) {
1355 assert(pkt
->req
->isUncacheable());
1356 handleUncacheableWriteResp(pkt
);
1360 // we have dealt with any (uncacheable) writes above, from here on
1361 // we know we are dealing with an MSHR due to a miss or a prefetch
1362 MSHR
*mshr
= dynamic_cast<MSHR
*>(pkt
->popSenderState());
1365 if (mshr
== noTargetMSHR
) {
1366 // we always clear at least one target
1367 clearBlocked(Blocked_NoTargets
);
1368 noTargetMSHR
= nullptr;
1371 // Initial target is used just for stats
1372 MSHR::Target
*initial_tgt
= mshr
->getTarget();
1373 int stats_cmd_idx
= initial_tgt
->pkt
->cmdToIndex();
1374 Tick miss_latency
= curTick() - initial_tgt
->recvTime
;
1376 if (pkt
->req
->isUncacheable()) {
1377 assert(pkt
->req
->masterId() < system
->maxMasters());
1378 mshr_uncacheable_lat
[stats_cmd_idx
][pkt
->req
->masterId()] +=
1381 assert(pkt
->req
->masterId() < system
->maxMasters());
1382 mshr_miss_latency
[stats_cmd_idx
][pkt
->req
->masterId()] +=
1386 bool wasFull
= mshrQueue
.isFull();
1388 PacketList writebacks
;
1390 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
1392 bool is_fill
= !mshr
->isForward
&&
1393 (pkt
->isRead() || pkt
->cmd
== MemCmd::UpgradeResp
);
1395 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), pkt
->isSecure());
1396 const bool valid_blk
= blk
&& blk
->isValid();
1397 // If the response indicates that there are no sharers and we
1398 // either had the block already or the response is filling we can
1399 // promote our copy to writable
1400 if (!pkt
->hasSharers() &&
1401 (is_fill
|| (valid_blk
&& !pkt
->req
->isCacheInvalidate()))) {
1402 mshr
->promoteWritable();
1405 if (is_fill
&& !is_error
) {
1406 DPRINTF(Cache
, "Block for addr %#llx being updated in Cache\n",
1409 blk
= handleFill(pkt
, blk
, writebacks
, mshr
->allocOnFill());
1410 assert(blk
!= nullptr);
1413 // allow invalidation responses originating from write-line
1414 // requests to be discarded
1415 bool is_invalidate
= pkt
->isInvalidate();
1417 // The block was marked as not readable while there was a pending
1418 // cache maintenance operation, restore its flag.
1419 if (pkt
->isClean() && !is_invalidate
&& valid_blk
) {
1420 blk
->status
|= BlkReadable
;
1423 // First offset for critical word first calculations
1424 int initial_offset
= initial_tgt
->pkt
->getOffset(blkSize
);
1426 bool from_cache
= false;
1427 MSHR::TargetList targets
= mshr
->extractServiceableTargets(pkt
);
1428 for (auto &target
: targets
) {
1429 Packet
*tgt_pkt
= target
.pkt
;
1430 switch (target
.source
) {
1431 case MSHR::Target::FromCPU
:
1432 Tick completion_time
;
1433 // Here we charge on completion_time the delay of the xbar if the
1434 // packet comes from it, charged on headerDelay.
1435 completion_time
= pkt
->headerDelay
;
1437 // Software prefetch handling for cache closest to core
1438 if (tgt_pkt
->cmd
.isSWPrefetch()) {
1439 // a software prefetch would have already been ack'd
1440 // immediately with dummy data so the core would be able to
1441 // retire it. This request completes right here, so we
1443 delete tgt_pkt
->req
;
1445 break; // skip response
1448 // keep track of whether we have responded to another
1450 from_cache
= from_cache
|| tgt_pkt
->fromCache();
1452 // unlike the other packet flows, where data is found in other
1453 // caches or memory and brought back, write-line requests always
1454 // have the data right away, so the above check for "is fill?"
1455 // cannot actually be determined until examining the stored MSHR
1456 // state. We "catch up" with that logic here, which is duplicated
1458 if (tgt_pkt
->cmd
== MemCmd::WriteLineReq
) {
1460 // we got the block in a writable state, so promote
1461 // any deferred targets if possible
1462 mshr
->promoteWritable();
1463 // NB: we use the original packet here and not the response!
1464 blk
= handleFill(tgt_pkt
, blk
, writebacks
,
1465 targets
.allocOnFill
);
1466 assert(blk
!= nullptr);
1468 // treat as a fill, and discard the invalidation
1471 is_invalidate
= false;
1475 satisfyRequest(tgt_pkt
, blk
, true, mshr
->hasPostDowngrade());
1477 // How many bytes past the first request is this one
1478 int transfer_offset
=
1479 tgt_pkt
->getOffset(blkSize
) - initial_offset
;
1480 if (transfer_offset
< 0) {
1481 transfer_offset
+= blkSize
;
1484 // If not critical word (offset) return payloadDelay.
1485 // responseLatency is the latency of the return path
1486 // from lower level caches/memory to an upper level cache or
1488 completion_time
+= clockEdge(responseLatency
) +
1489 (transfer_offset
? pkt
->payloadDelay
: 0);
1491 assert(!tgt_pkt
->req
->isUncacheable());
1493 assert(tgt_pkt
->req
->masterId() < system
->maxMasters());
1494 missLatency
[tgt_pkt
->cmdToIndex()][tgt_pkt
->req
->masterId()] +=
1495 completion_time
- target
.recvTime
;
1496 } else if (pkt
->cmd
== MemCmd::UpgradeFailResp
) {
1497 // failed StoreCond upgrade
1498 assert(tgt_pkt
->cmd
== MemCmd::StoreCondReq
||
1499 tgt_pkt
->cmd
== MemCmd::StoreCondFailReq
||
1500 tgt_pkt
->cmd
== MemCmd::SCUpgradeFailReq
);
1501 // responseLatency is the latency of the return path
1502 // from lower level caches/memory to an upper level cache or
1504 completion_time
+= clockEdge(responseLatency
) +
1506 tgt_pkt
->req
->setExtraData(0);
1508 // We are about to send a response to a cache above
1509 // that asked for an invalidation; we need to
1510 // invalidate our copy immediately as the most
1511 // up-to-date copy of the block will now be in the
1512 // cache above. It will also prevent this cache from
1513 // responding (if the block was previously dirty) to
1514 // snoops as they should snoop the caches above where
1515 // they will get the response from.
1516 if (is_invalidate
&& blk
&& blk
->isValid()) {
1517 invalidateBlock(blk
);
1519 // not a cache fill, just forwarding response
1520 // responseLatency is the latency of the return path
1521 // from lower level cahces/memory to the core.
1522 completion_time
+= clockEdge(responseLatency
) +
1524 if (pkt
->isRead() && !is_error
) {
1526 assert(pkt
->getAddr() == tgt_pkt
->getAddr());
1527 assert(pkt
->getSize() >= tgt_pkt
->getSize());
1529 tgt_pkt
->setData(pkt
->getConstPtr
<uint8_t>());
1532 tgt_pkt
->makeTimingResponse();
1533 // if this packet is an error copy that to the new packet
1535 tgt_pkt
->copyError(pkt
);
1536 if (tgt_pkt
->cmd
== MemCmd::ReadResp
&&
1537 (is_invalidate
|| mshr
->hasPostInvalidate())) {
1538 // If intermediate cache got ReadRespWithInvalidate,
1539 // propagate that. Response should not have
1540 // isInvalidate() set otherwise.
1541 tgt_pkt
->cmd
= MemCmd::ReadRespWithInvalidate
;
1542 DPRINTF(Cache
, "%s: updated cmd to %s\n", __func__
,
1545 // Reset the bus additional time as it is now accounted for
1546 tgt_pkt
->headerDelay
= tgt_pkt
->payloadDelay
= 0;
1547 cpuSidePort
->schedTimingResp(tgt_pkt
, completion_time
, true);
1550 case MSHR::Target::FromPrefetcher
:
1551 assert(tgt_pkt
->cmd
== MemCmd::HardPFReq
);
1553 blk
->status
|= BlkHWPrefetched
;
1554 delete tgt_pkt
->req
;
1558 case MSHR::Target::FromSnoop
:
1559 // I don't believe that a snoop can be in an error state
1561 // response to snoop request
1562 DPRINTF(Cache
, "processing deferred snoop...\n");
1563 // If the response is invalidating, a snooping target can
1564 // be satisfied if it is also invalidating. If the reponse is, not
1565 // only invalidating, but more specifically an InvalidateResp and
1566 // the MSHR was created due to an InvalidateReq then a cache above
1567 // is waiting to satisfy a WriteLineReq. In this case even an
1568 // non-invalidating snoop is added as a target here since this is
1569 // the ordering point. When the InvalidateResp reaches this cache,
1570 // the snooping target will snoop further the cache above with the
1572 assert(!is_invalidate
|| pkt
->cmd
== MemCmd::InvalidateResp
||
1573 pkt
->req
->isCacheMaintenance() ||
1574 mshr
->hasPostInvalidate());
1575 handleSnoop(tgt_pkt
, blk
, true, true, mshr
->hasPostInvalidate());
1579 panic("Illegal target->source enum %d\n", target
.source
);
1583 maintainClusivity(from_cache
, blk
);
1585 if (blk
&& blk
->isValid()) {
1586 // an invalidate response stemming from a write line request
1587 // should not invalidate the block, so check if the
1588 // invalidation should be discarded
1589 if (is_invalidate
|| mshr
->hasPostInvalidate()) {
1590 invalidateBlock(blk
);
1591 } else if (mshr
->hasPostDowngrade()) {
1592 blk
->status
&= ~BlkWritable
;
1596 if (mshr
->promoteDeferredTargets()) {
1597 // avoid later read getting stale data while write miss is
1598 // outstanding.. see comment in timingAccess()
1600 blk
->status
&= ~BlkReadable
;
1602 mshrQueue
.markPending(mshr
);
1603 schedMemSideSendEvent(clockEdge() + pkt
->payloadDelay
);
1605 mshrQueue
.deallocate(mshr
);
1606 if (wasFull
&& !mshrQueue
.isFull()) {
1607 clearBlocked(Blocked_NoMSHRs
);
1610 // Request the bus for a prefetch if this deallocation freed enough
1611 // MSHRs for a prefetch to take place
1612 if (prefetcher
&& mshrQueue
.canPrefetch()) {
1613 Tick next_pf_time
= std::max(prefetcher
->nextPrefetchReadyTime(),
1615 if (next_pf_time
!= MaxTick
)
1616 schedMemSideSendEvent(next_pf_time
);
1619 // reset the xbar additional timinig as it is now accounted for
1620 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
1622 // copy writebacks to write buffer
1623 doWritebacks(writebacks
, forward_time
);
1625 // if we used temp block, check to see if its valid and then clear it out
1626 if (blk
== tempBlock
&& tempBlock
->isValid()) {
1627 // We use forwardLatency here because we are copying
1628 // Writebacks/CleanEvicts to write buffer. It specifies the latency to
1629 // allocate an internal buffer and to schedule an event to the
1631 if (blk
->isDirty() || writebackClean
) {
1632 PacketPtr wbPkt
= writebackBlk(blk
);
1633 allocateWriteBuffer(wbPkt
, forward_time
);
1634 // Set BLOCK_CACHED flag if cached above.
1635 if (isCachedAbove(wbPkt
))
1636 wbPkt
->setBlockCached();
1638 PacketPtr wcPkt
= cleanEvictBlk(blk
);
1639 // Check to see if block is cached above. If not allocate
1641 if (isCachedAbove(wcPkt
))
1644 allocateWriteBuffer(wcPkt
, forward_time
);
1646 invalidateBlock(blk
);
1649 DPRINTF(CacheVerbose
, "%s: Leaving with %s\n", __func__
, pkt
->print());
1654 Cache::writebackBlk(CacheBlk
*blk
)
1656 chatty_assert(!isReadOnly
|| writebackClean
,
1657 "Writeback from read-only cache");
1658 assert(blk
&& blk
->isValid() && (blk
->isDirty() || writebackClean
));
1660 writebacks
[Request::wbMasterId
]++;
1662 Request
*req
= new Request(tags
->regenerateBlkAddr(blk
), blkSize
, 0,
1663 Request::wbMasterId
);
1664 if (blk
->isSecure())
1665 req
->setFlags(Request::SECURE
);
1667 req
->taskId(blk
->task_id
);
1670 new Packet(req
, blk
->isDirty() ?
1671 MemCmd::WritebackDirty
: MemCmd::WritebackClean
);
1673 DPRINTF(Cache
, "Create Writeback %s writable: %d, dirty: %d\n",
1674 pkt
->print(), blk
->isWritable(), blk
->isDirty());
1676 if (blk
->isWritable()) {
1677 // not asserting shared means we pass the block in modified
1678 // state, mark our own block non-writeable
1679 blk
->status
&= ~BlkWritable
;
1681 // we are in the Owned state, tell the receiver
1682 pkt
->setHasSharers();
1685 // make sure the block is not marked dirty
1686 blk
->status
&= ~BlkDirty
;
1689 std::memcpy(pkt
->getPtr
<uint8_t>(), blk
->data
, blkSize
);
1695 Cache::writecleanBlk(CacheBlk
*blk
, Request::Flags dest
, PacketId id
)
1697 Request
*req
= new Request(tags
->regenerateBlkAddr(blk
), blkSize
, 0,
1698 Request::wbMasterId
);
1699 if (blk
->isSecure()) {
1700 req
->setFlags(Request::SECURE
);
1702 req
->taskId(blk
->task_id
);
1704 PacketPtr pkt
= new Packet(req
, MemCmd::WriteClean
, blkSize
, id
);
1707 req
->setFlags(dest
);
1708 pkt
->setWriteThrough();
1711 DPRINTF(Cache
, "Create %s writable: %d, dirty: %d\n", pkt
->print(),
1712 blk
->isWritable(), blk
->isDirty());
1714 if (blk
->isWritable()) {
1715 // not asserting shared means we pass the block in modified
1716 // state, mark our own block non-writeable
1717 blk
->status
&= ~BlkWritable
;
1719 // we are in the Owned state, tell the receiver
1720 pkt
->setHasSharers();
1723 // make sure the block is not marked dirty
1724 blk
->status
&= ~BlkDirty
;
1727 std::memcpy(pkt
->getPtr
<uint8_t>(), blk
->data
, blkSize
);
1734 Cache::cleanEvictBlk(CacheBlk
*blk
)
1736 assert(!writebackClean
);
1737 assert(blk
&& blk
->isValid() && !blk
->isDirty());
1738 // Creating a zero sized write, a message to the snoop filter
1740 new Request(tags
->regenerateBlkAddr(blk
), blkSize
, 0,
1741 Request::wbMasterId
);
1742 if (blk
->isSecure())
1743 req
->setFlags(Request::SECURE
);
1745 req
->taskId(blk
->task_id
);
1747 PacketPtr pkt
= new Packet(req
, MemCmd::CleanEvict
);
1749 DPRINTF(Cache
, "Create CleanEvict %s\n", pkt
->print());
1755 Cache::memWriteback()
1757 CacheBlkVisitorWrapper
visitor(*this, &Cache::writebackVisitor
);
1758 tags
->forEachBlk(visitor
);
1762 Cache::memInvalidate()
1764 CacheBlkVisitorWrapper
visitor(*this, &Cache::invalidateVisitor
);
1765 tags
->forEachBlk(visitor
);
1769 Cache::isDirty() const
1771 CacheBlkIsDirtyVisitor visitor
;
1772 tags
->forEachBlk(visitor
);
1774 return visitor
.isDirty();
1778 Cache::writebackVisitor(CacheBlk
&blk
)
1780 if (blk
.isDirty()) {
1781 assert(blk
.isValid());
1783 Request
request(tags
->regenerateBlkAddr(&blk
), blkSize
, 0,
1784 Request::funcMasterId
);
1785 request
.taskId(blk
.task_id
);
1786 if (blk
.isSecure()) {
1787 request
.setFlags(Request::SECURE
);
1790 Packet
packet(&request
, MemCmd::WriteReq
);
1791 packet
.dataStatic(blk
.data
);
1793 memSidePort
->sendFunctional(&packet
);
1795 blk
.status
&= ~BlkDirty
;
1802 Cache::invalidateVisitor(CacheBlk
&blk
)
1806 warn_once("Invalidating dirty cache lines. Expect things to break.\n");
1808 if (blk
.isValid()) {
1809 assert(!blk
.isDirty());
1810 invalidateBlock(&blk
);
1817 Cache::allocateBlock(Addr addr
, bool is_secure
, PacketList
&writebacks
)
1819 // Find replacement victim
1820 CacheBlk
*blk
= tags
->findVictim(addr
);
1822 // It is valid to return nullptr if there is no victim
1826 if (blk
->isValid()) {
1827 Addr repl_addr
= tags
->regenerateBlkAddr(blk
);
1828 MSHR
*repl_mshr
= mshrQueue
.findMatch(repl_addr
, blk
->isSecure());
1830 // must be an outstanding upgrade or clean request
1831 // on a block we're about to replace...
1832 assert((!blk
->isWritable() && repl_mshr
->needsWritable()) ||
1833 repl_mshr
->isCleaning());
1834 // too hard to replace block with transient state
1835 // allocation failed, block not inserted
1838 DPRINTF(Cache
, "replacement: replacing %#llx (%s) with %#llx "
1839 "(%s): %s\n", repl_addr
, blk
->isSecure() ? "s" : "ns",
1840 addr
, is_secure
? "s" : "ns",
1841 blk
->isDirty() ? "writeback" : "clean");
1843 if (blk
->wasPrefetched()) {
1846 // Will send up Writeback/CleanEvict snoops via isCachedAbove
1847 // when pushing this writeback list into the write buffer.
1848 if (blk
->isDirty() || writebackClean
) {
1849 // Save writeback packet for handling by caller
1850 writebacks
.push_back(writebackBlk(blk
));
1852 writebacks
.push_back(cleanEvictBlk(blk
));
1861 Cache::invalidateBlock(CacheBlk
*blk
)
1863 if (blk
!= tempBlock
)
1864 tags
->invalidate(blk
);
1868 // Note that the reason we return a list of writebacks rather than
1869 // inserting them directly in the write buffer is that this function
1870 // is called by both atomic and timing-mode accesses, and in atomic
1871 // mode we don't mess with the write buffer (we just perform the
1872 // writebacks atomically once the original request is complete).
1874 Cache::handleFill(PacketPtr pkt
, CacheBlk
*blk
, PacketList
&writebacks
,
1877 assert(pkt
->isResponse() || pkt
->cmd
== MemCmd::WriteLineReq
);
1878 Addr addr
= pkt
->getAddr();
1879 bool is_secure
= pkt
->isSecure();
1881 CacheBlk::State old_state
= blk
? blk
->status
: 0;
1884 // When handling a fill, we should have no writes to this line.
1885 assert(addr
== pkt
->getBlockAddr(blkSize
));
1886 assert(!writeBuffer
.findMatch(addr
, is_secure
));
1888 if (blk
== nullptr) {
1889 // better have read new data...
1890 assert(pkt
->hasData());
1892 // only read responses and write-line requests have data;
1893 // note that we don't write the data here for write-line - that
1894 // happens in the subsequent call to satisfyRequest
1895 assert(pkt
->isRead() || pkt
->cmd
== MemCmd::WriteLineReq
);
1897 // need to do a replacement if allocating, otherwise we stick
1898 // with the temporary storage
1899 blk
= allocate
? allocateBlock(addr
, is_secure
, writebacks
) : nullptr;
1901 if (blk
== nullptr) {
1902 // No replaceable block or a mostly exclusive
1903 // cache... just use temporary storage to complete the
1904 // current request and then get rid of it
1905 assert(!tempBlock
->isValid());
1907 tempBlock
->set
= tags
->extractSet(addr
);
1908 tempBlock
->tag
= tags
->extractTag(addr
);
1910 tempBlock
->status
|= BlkSecure
;
1912 DPRINTF(Cache
, "using temp block for %#llx (%s)\n", addr
,
1913 is_secure
? "s" : "ns");
1915 tags
->insertBlock(pkt
, blk
);
1918 // we should never be overwriting a valid block
1919 assert(!blk
->isValid());
1921 // existing block... probably an upgrade
1922 assert(blk
->tag
== tags
->extractTag(addr
));
1923 // either we're getting new data or the block should already be valid
1924 assert(pkt
->hasData() || blk
->isValid());
1925 // don't clear block status... if block is already dirty we
1926 // don't want to lose that
1930 blk
->status
|= BlkSecure
;
1931 blk
->status
|= BlkValid
| BlkReadable
;
1933 // sanity check for whole-line writes, which should always be
1934 // marked as writable as part of the fill, and then later marked
1935 // dirty as part of satisfyRequest
1936 if (pkt
->cmd
== MemCmd::WriteLineReq
) {
1937 assert(!pkt
->hasSharers());
1940 // here we deal with setting the appropriate state of the line,
1941 // and we start by looking at the hasSharers flag, and ignore the
1942 // cacheResponding flag (normally signalling dirty data) if the
1943 // packet has sharers, thus the line is never allocated as Owned
1944 // (dirty but not writable), and always ends up being either
1945 // Shared, Exclusive or Modified, see Packet::setCacheResponding
1947 if (!pkt
->hasSharers()) {
1948 // we could get a writable line from memory (rather than a
1949 // cache) even in a read-only cache, note that we set this bit
1950 // even for a read-only cache, possibly revisit this decision
1951 blk
->status
|= BlkWritable
;
1953 // check if we got this via cache-to-cache transfer (i.e., from a
1954 // cache that had the block in Modified or Owned state)
1955 if (pkt
->cacheResponding()) {
1956 // we got the block in Modified state, and invalidated the
1958 blk
->status
|= BlkDirty
;
1960 chatty_assert(!isReadOnly
, "Should never see dirty snoop response "
1961 "in read-only cache %s\n", name());
1965 DPRINTF(Cache
, "Block addr %#llx (%s) moving from state %x to %s\n",
1966 addr
, is_secure
? "s" : "ns", old_state
, blk
->print());
1968 // if we got new data, copy it in (checking for a read response
1969 // and a response that has data is the same in the end)
1970 if (pkt
->isRead()) {
1972 assert(pkt
->hasData());
1973 assert(pkt
->getSize() == blkSize
);
1975 std::memcpy(blk
->data
, pkt
->getConstPtr
<uint8_t>(), blkSize
);
1977 // We pay for fillLatency here.
1978 blk
->whenReady
= clockEdge() + fillLatency
* clockPeriod() +
1985 /////////////////////////////////////////////////////
1987 // Snoop path: requests coming in from the memory side
1989 /////////////////////////////////////////////////////
1992 Cache::doTimingSupplyResponse(PacketPtr req_pkt
, const uint8_t *blk_data
,
1993 bool already_copied
, bool pending_inval
)
1996 assert(req_pkt
->isRequest());
1997 assert(req_pkt
->needsResponse());
1999 DPRINTF(Cache
, "%s: for %s\n", __func__
, req_pkt
->print());
2000 // timing-mode snoop responses require a new packet, unless we
2001 // already made a copy...
2002 PacketPtr pkt
= req_pkt
;
2003 if (!already_copied
)
2004 // do not clear flags, and allocate space for data if the
2005 // packet needs it (the only packets that carry data are read
2007 pkt
= new Packet(req_pkt
, false, req_pkt
->isRead());
2009 assert(req_pkt
->req
->isUncacheable() || req_pkt
->isInvalidate() ||
2011 pkt
->makeTimingResponse();
2012 if (pkt
->isRead()) {
2013 pkt
->setDataFromBlock(blk_data
, blkSize
);
2015 if (pkt
->cmd
== MemCmd::ReadResp
&& pending_inval
) {
2016 // Assume we defer a response to a read from a far-away cache
2017 // A, then later defer a ReadExcl from a cache B on the same
2018 // bus as us. We'll assert cacheResponding in both cases, but
2019 // in the latter case cacheResponding will keep the
2020 // invalidation from reaching cache A. This special response
2021 // tells cache A that it gets the block to satisfy its read,
2022 // but must immediately invalidate it.
2023 pkt
->cmd
= MemCmd::ReadRespWithInvalidate
;
2025 // Here we consider forward_time, paying for just forward latency and
2026 // also charging the delay provided by the xbar.
2027 // forward_time is used as send_time in next allocateWriteBuffer().
2028 Tick forward_time
= clockEdge(forwardLatency
) + pkt
->headerDelay
;
2029 // Here we reset the timing of the packet.
2030 pkt
->headerDelay
= pkt
->payloadDelay
= 0;
2031 DPRINTF(CacheVerbose
, "%s: created response: %s tick: %lu\n", __func__
,
2032 pkt
->print(), forward_time
);
2033 memSidePort
->schedTimingSnoopResp(pkt
, forward_time
, true);
2037 Cache::handleSnoop(PacketPtr pkt
, CacheBlk
*blk
, bool is_timing
,
2038 bool is_deferred
, bool pending_inval
)
2040 DPRINTF(CacheVerbose
, "%s: for %s\n", __func__
, pkt
->print());
2041 // deferred snoops can only happen in timing mode
2042 assert(!(is_deferred
&& !is_timing
));
2043 // pending_inval only makes sense on deferred snoops
2044 assert(!(pending_inval
&& !is_deferred
));
2045 assert(pkt
->isRequest());
2047 // the packet may get modified if we or a forwarded snooper
2048 // responds in atomic mode, so remember a few things about the
2049 // original packet up front
2050 bool invalidate
= pkt
->isInvalidate();
2051 bool M5_VAR_USED needs_writable
= pkt
->needsWritable();
2053 // at the moment we could get an uncacheable write which does not
2054 // have the invalidate flag, and we need a suitable way of dealing
2056 panic_if(invalidate
&& pkt
->req
->isUncacheable(),
2057 "%s got an invalidating uncacheable snoop request %s",
2058 name(), pkt
->print());
2060 uint32_t snoop_delay
= 0;
2062 if (forwardSnoops
) {
2063 // first propagate snoop upward to see if anyone above us wants to
2064 // handle it. save & restore packet src since it will get
2065 // rewritten to be relative to cpu-side bus (if any)
2066 bool alreadyResponded
= pkt
->cacheResponding();
2068 // copy the packet so that we can clear any flags before
2069 // forwarding it upwards, we also allocate data (passing
2070 // the pointer along in case of static data), in case
2071 // there is a snoop hit in upper levels
2072 Packet
snoopPkt(pkt
, true, true);
2073 snoopPkt
.setExpressSnoop();
2074 // the snoop packet does not need to wait any additional
2076 snoopPkt
.headerDelay
= snoopPkt
.payloadDelay
= 0;
2077 cpuSidePort
->sendTimingSnoopReq(&snoopPkt
);
2079 // add the header delay (including crossbar and snoop
2080 // delays) of the upward snoop to the snoop delay for this
2082 snoop_delay
+= snoopPkt
.headerDelay
;
2084 if (snoopPkt
.cacheResponding()) {
2085 // cache-to-cache response from some upper cache
2086 assert(!alreadyResponded
);
2087 pkt
->setCacheResponding();
2089 // upstream cache has the block, or has an outstanding
2090 // MSHR, pass the flag on
2091 if (snoopPkt
.hasSharers()) {
2092 pkt
->setHasSharers();
2094 // If this request is a prefetch or clean evict and an upper level
2095 // signals block present, make sure to propagate the block
2096 // presence to the requester.
2097 if (snoopPkt
.isBlockCached()) {
2098 pkt
->setBlockCached();
2100 // If the request was satisfied by snooping the cache
2101 // above, mark the original packet as satisfied too.
2102 if (snoopPkt
.satisfied()) {
2103 pkt
->setSatisfied();
2106 cpuSidePort
->sendAtomicSnoop(pkt
);
2107 if (!alreadyResponded
&& pkt
->cacheResponding()) {
2108 // cache-to-cache response from some upper cache:
2109 // forward response to original requester
2110 assert(pkt
->isResponse());
2115 bool respond
= false;
2116 bool blk_valid
= blk
&& blk
->isValid();
2117 if (pkt
->isClean()) {
2118 if (blk_valid
&& blk
->isDirty()) {
2119 DPRINTF(CacheVerbose
, "%s: packet (snoop) %s found block: %s\n",
2120 __func__
, pkt
->print(), blk
->print());
2121 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest(), pkt
->id
);
2122 PacketList writebacks
;
2123 writebacks
.push_back(wb_pkt
);
2126 // anything that is merely forwarded pays for the forward
2127 // latency and the delay provided by the crossbar
2128 Tick forward_time
= clockEdge(forwardLatency
) +
2130 doWritebacks(writebacks
, forward_time
);
2132 doWritebacksAtomic(writebacks
);
2134 pkt
->setSatisfied();
2136 } else if (!blk_valid
) {
2137 DPRINTF(CacheVerbose
, "%s: snoop miss for %s\n", __func__
,
2140 // we no longer have the block, and will not respond, but a
2141 // packet was allocated in MSHR::handleSnoop and we have
2143 assert(pkt
->needsResponse());
2145 // we have passed the block to a cache upstream, that
2146 // cache should be responding
2147 assert(pkt
->cacheResponding());
2153 DPRINTF(Cache
, "%s: snoop hit for %s, old state is %s\n", __func__
,
2154 pkt
->print(), blk
->print());
2156 // We may end up modifying both the block state and the packet (if
2157 // we respond in atomic mode), so just figure out what to do now
2158 // and then do it later. We respond to all snoops that need
2159 // responses provided we have the block in dirty state. The
2160 // invalidation itself is taken care of below. We don't respond to
2161 // cache maintenance operations as this is done by the destination
2163 respond
= blk
->isDirty() && pkt
->needsResponse();
2165 chatty_assert(!(isReadOnly
&& blk
->isDirty()), "Should never have "
2166 "a dirty block in a read-only cache %s\n", name());
2169 // Invalidate any prefetch's from below that would strip write permissions
2170 // MemCmd::HardPFReq is only observed by upstream caches. After missing
2171 // above and in it's own cache, a new MemCmd::ReadReq is created that
2172 // downstream caches observe.
2173 if (pkt
->mustCheckAbove()) {
2174 DPRINTF(Cache
, "Found addr %#llx in upper level cache for snoop %s "
2175 "from lower cache\n", pkt
->getAddr(), pkt
->print());
2176 pkt
->setBlockCached();
2180 if (pkt
->isRead() && !invalidate
) {
2181 // reading without requiring the line in a writable state
2182 assert(!needs_writable
);
2183 pkt
->setHasSharers();
2185 // if the requesting packet is uncacheable, retain the line in
2186 // the current state, otherwhise unset the writable flag,
2187 // which means we go from Modified to Owned (and will respond
2188 // below), remain in Owned (and will respond below), from
2189 // Exclusive to Shared, or remain in Shared
2190 if (!pkt
->req
->isUncacheable())
2191 blk
->status
&= ~BlkWritable
;
2192 DPRINTF(Cache
, "new state is %s\n", blk
->print());
2196 // prevent anyone else from responding, cache as well as
2197 // memory, and also prevent any memory from even seeing the
2199 pkt
->setCacheResponding();
2200 if (!pkt
->isClean() && blk
->isWritable()) {
2201 // inform the cache hierarchy that this cache had the line
2202 // in the Modified state so that we avoid unnecessary
2203 // invalidations (see Packet::setResponderHadWritable)
2204 pkt
->setResponderHadWritable();
2206 // in the case of an uncacheable request there is no point
2207 // in setting the responderHadWritable flag, but since the
2208 // recipient does not care there is no harm in doing so
2210 // if the packet has needsWritable set we invalidate our
2211 // copy below and all other copies will be invalidates
2212 // through express snoops, and if needsWritable is not set
2213 // we already called setHasSharers above
2216 // if we are returning a writable and dirty (Modified) line,
2217 // we should be invalidating the line
2218 panic_if(!invalidate
&& !pkt
->hasSharers(),
2219 "%s is passing a Modified line through %s, "
2220 "but keeping the block", name(), pkt
->print());
2223 doTimingSupplyResponse(pkt
, blk
->data
, is_deferred
, pending_inval
);
2225 pkt
->makeAtomicResponse();
2226 // packets such as upgrades do not actually have any data
2229 pkt
->setDataFromBlock(blk
->data
, blkSize
);
2233 if (!respond
&& is_deferred
) {
2234 assert(pkt
->needsResponse());
2236 // if we copied the deferred packet with the intention to
2237 // respond, but are not responding, then a cache above us must
2238 // be, and we can use this as the indication of whether this
2239 // is a packet where we created a copy of the request or not
2240 if (!pkt
->cacheResponding()) {
2247 // Do this last in case it deallocates block data or something
2249 if (blk_valid
&& invalidate
) {
2250 invalidateBlock(blk
);
2251 DPRINTF(Cache
, "new state is %s\n", blk
->print());
2259 Cache::recvTimingSnoopReq(PacketPtr pkt
)
2261 DPRINTF(CacheVerbose
, "%s: for %s\n", __func__
, pkt
->print());
2263 // Snoops shouldn't happen when bypassing caches
2264 assert(!system
->bypassCaches());
2266 // no need to snoop requests that are not in range
2267 if (!inRange(pkt
->getAddr())) {
2271 bool is_secure
= pkt
->isSecure();
2272 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), is_secure
);
2274 Addr blk_addr
= pkt
->getBlockAddr(blkSize
);
2275 MSHR
*mshr
= mshrQueue
.findMatch(blk_addr
, is_secure
);
2277 // Update the latency cost of the snoop so that the crossbar can
2278 // account for it. Do not overwrite what other neighbouring caches
2279 // have already done, rather take the maximum. The update is
2280 // tentative, for cases where we return before an upward snoop
2282 pkt
->snoopDelay
= std::max
<uint32_t>(pkt
->snoopDelay
,
2283 lookupLatency
* clockPeriod());
2285 // Inform request(Prefetch, CleanEvict or Writeback) from below of
2286 // MSHR hit, set setBlockCached.
2287 if (mshr
&& pkt
->mustCheckAbove()) {
2288 DPRINTF(Cache
, "Setting block cached for %s from lower cache on "
2289 "mshr hit\n", pkt
->print());
2290 pkt
->setBlockCached();
2294 // Bypass any existing cache maintenance requests if the request
2295 // has been satisfied already (i.e., the dirty block has been
2297 if (mshr
&& pkt
->req
->isCacheMaintenance() && pkt
->satisfied()) {
2301 // Let the MSHR itself track the snoop and decide whether we want
2302 // to go ahead and do the regular cache snoop
2303 if (mshr
&& mshr
->handleSnoop(pkt
, order
++)) {
2304 DPRINTF(Cache
, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
2305 "mshrs: %s\n", blk_addr
, is_secure
? "s" : "ns",
2308 if (mshr
->getNumTargets() > numTarget
)
2309 warn("allocating bonus target for snoop"); //handle later
2313 //We also need to check the writeback buffers and handle those
2314 WriteQueueEntry
*wb_entry
= writeBuffer
.findMatch(blk_addr
, is_secure
);
2316 DPRINTF(Cache
, "Snoop hit in writeback to addr %#llx (%s)\n",
2317 pkt
->getAddr(), is_secure
? "s" : "ns");
2318 // Expect to see only Writebacks and/or CleanEvicts here, both of
2319 // which should not be generated for uncacheable data.
2320 assert(!wb_entry
->isUncacheable());
2321 // There should only be a single request responsible for generating
2322 // Writebacks/CleanEvicts.
2323 assert(wb_entry
->getNumTargets() == 1);
2324 PacketPtr wb_pkt
= wb_entry
->getTarget()->pkt
;
2325 assert(wb_pkt
->isEviction() || wb_pkt
->cmd
== MemCmd::WriteClean
);
2327 if (pkt
->isEviction()) {
2328 // if the block is found in the write queue, set the BLOCK_CACHED
2329 // flag for Writeback/CleanEvict snoop. On return the snoop will
2330 // propagate the BLOCK_CACHED flag in Writeback packets and prevent
2331 // any CleanEvicts from travelling down the memory hierarchy.
2332 pkt
->setBlockCached();
2333 DPRINTF(Cache
, "%s: Squashing %s from lower cache on writequeue "
2334 "hit\n", __func__
, pkt
->print());
2338 // conceptually writebacks are no different to other blocks in
2339 // this cache, so the behaviour is modelled after handleSnoop,
2340 // the difference being that instead of querying the block
2341 // state to determine if it is dirty and writable, we use the
2342 // command and fields of the writeback packet
2343 bool respond
= wb_pkt
->cmd
== MemCmd::WritebackDirty
&&
2344 pkt
->needsResponse();
2345 bool have_writable
= !wb_pkt
->hasSharers();
2346 bool invalidate
= pkt
->isInvalidate();
2348 if (!pkt
->req
->isUncacheable() && pkt
->isRead() && !invalidate
) {
2349 assert(!pkt
->needsWritable());
2350 pkt
->setHasSharers();
2351 wb_pkt
->setHasSharers();
2355 pkt
->setCacheResponding();
2357 if (have_writable
) {
2358 pkt
->setResponderHadWritable();
2361 doTimingSupplyResponse(pkt
, wb_pkt
->getConstPtr
<uint8_t>(),
2365 if (invalidate
&& wb_pkt
->cmd
!= MemCmd::WriteClean
) {
2366 // Invalidation trumps our writeback... discard here
2367 // Note: markInService will remove entry from writeback buffer.
2368 markInService(wb_entry
);
2373 // If this was a shared writeback, there may still be
2374 // other shared copies above that require invalidation.
2375 // We could be more selective and return here if the
2376 // request is non-exclusive or if the writeback is
2378 uint32_t snoop_delay
= handleSnoop(pkt
, blk
, true, false, false);
2380 // Override what we did when we first saw the snoop, as we now
2381 // also have the cost of the upwards snoops to account for
2382 pkt
->snoopDelay
= std::max
<uint32_t>(pkt
->snoopDelay
, snoop_delay
+
2383 lookupLatency
* clockPeriod());
2387 Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt
)
2389 // Express snoop responses from master to slave, e.g., from L1 to L2
2390 cache
->recvTimingSnoopResp(pkt
);
2395 Cache::recvAtomicSnoop(PacketPtr pkt
)
2397 // Snoops shouldn't happen when bypassing caches
2398 assert(!system
->bypassCaches());
2400 // no need to snoop requests that are not in range.
2401 if (!inRange(pkt
->getAddr())) {
2405 CacheBlk
*blk
= tags
->findBlock(pkt
->getAddr(), pkt
->isSecure());
2406 uint32_t snoop_delay
= handleSnoop(pkt
, blk
, false, false, false);
2407 return snoop_delay
+ lookupLatency
* clockPeriod();
2412 Cache::getNextQueueEntry()
2414 // Check both MSHR queue and write buffer for potential requests,
2415 // note that null does not mean there is no request, it could
2416 // simply be that it is not ready
2417 MSHR
*miss_mshr
= mshrQueue
.getNext();
2418 WriteQueueEntry
*wq_entry
= writeBuffer
.getNext();
2420 // If we got a write buffer request ready, first priority is a
2421 // full write buffer, otherwise we favour the miss requests
2422 if (wq_entry
&& (writeBuffer
.isFull() || !miss_mshr
)) {
2423 // need to search MSHR queue for conflicting earlier miss.
2424 MSHR
*conflict_mshr
=
2425 mshrQueue
.findPending(wq_entry
->blkAddr
,
2426 wq_entry
->isSecure
);
2428 if (conflict_mshr
&& conflict_mshr
->order
< wq_entry
->order
) {
2429 // Service misses in order until conflict is cleared.
2430 return conflict_mshr
;
2432 // @todo Note that we ignore the ready time of the conflict here
2435 // No conflicts; issue write
2437 } else if (miss_mshr
) {
2438 // need to check for conflicting earlier writeback
2439 WriteQueueEntry
*conflict_mshr
=
2440 writeBuffer
.findPending(miss_mshr
->blkAddr
,
2441 miss_mshr
->isSecure
);
2442 if (conflict_mshr
) {
2443 // not sure why we don't check order here... it was in the
2444 // original code but commented out.
2446 // The only way this happens is if we are
2447 // doing a write and we didn't have permissions
2448 // then subsequently saw a writeback (owned got evicted)
2449 // We need to make sure to perform the writeback first
2450 // To preserve the dirty data, then we can issue the write
2452 // should we return wq_entry here instead? I.e. do we
2453 // have to flush writes in order? I don't think so... not
2454 // for Alpha anyway. Maybe for x86?
2455 return conflict_mshr
;
2457 // @todo Note that we ignore the ready time of the conflict here
2460 // No conflicts; issue read
2464 // fall through... no pending requests. Try a prefetch.
2465 assert(!miss_mshr
&& !wq_entry
);
2466 if (prefetcher
&& mshrQueue
.canPrefetch()) {
2467 // If we have a miss queue slot, we can try a prefetch
2468 PacketPtr pkt
= prefetcher
->getPacket();
2470 Addr pf_addr
= pkt
->getBlockAddr(blkSize
);
2471 if (!tags
->findBlock(pf_addr
, pkt
->isSecure()) &&
2472 !mshrQueue
.findMatch(pf_addr
, pkt
->isSecure()) &&
2473 !writeBuffer
.findMatch(pf_addr
, pkt
->isSecure())) {
2474 // Update statistic on number of prefetches issued
2475 // (hwpf_mshr_misses)
2476 assert(pkt
->req
->masterId() < system
->maxMasters());
2477 mshr_misses
[pkt
->cmdToIndex()][pkt
->req
->masterId()]++;
2479 // allocate an MSHR and return it, note
2480 // that we send the packet straight away, so do not
2481 // schedule the send
2482 return allocateMissBuffer(pkt
, curTick(), false);
2484 // free the request and packet
2495 Cache::isCachedAbove(PacketPtr pkt
, bool is_timing
) const
2499 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
2500 // Writeback snoops into upper level caches to check for copies of the
2501 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
2502 // packet, the cache can inform the crossbar below of presence or absence
2505 Packet
snoop_pkt(pkt
, true, false);
2506 snoop_pkt
.setExpressSnoop();
2507 // Assert that packet is either Writeback or CleanEvict and not a
2508 // prefetch request because prefetch requests need an MSHR and may
2509 // generate a snoop response.
2510 assert(pkt
->isEviction() || pkt
->cmd
== MemCmd::WriteClean
);
2511 snoop_pkt
.senderState
= nullptr;
2512 cpuSidePort
->sendTimingSnoopReq(&snoop_pkt
);
2513 // Writeback/CleanEvict snoops do not generate a snoop response.
2514 assert(!(snoop_pkt
.cacheResponding()));
2515 return snoop_pkt
.isBlockCached();
2517 cpuSidePort
->sendAtomicSnoop(pkt
);
2518 return pkt
->isBlockCached();
2523 Cache::nextQueueReadyTime() const
2525 Tick nextReady
= std::min(mshrQueue
.nextReadyTime(),
2526 writeBuffer
.nextReadyTime());
2528 // Don't signal prefetch ready time if no MSHRs available
2529 // Will signal once enoguh MSHRs are deallocated
2530 if (prefetcher
&& mshrQueue
.canPrefetch()) {
2531 nextReady
= std::min(nextReady
,
2532 prefetcher
->nextPrefetchReadyTime());
2539 Cache::sendMSHRQueuePacket(MSHR
* mshr
)
2543 // use request from 1st target
2544 PacketPtr tgt_pkt
= mshr
->getTarget()->pkt
;
2546 DPRINTF(Cache
, "%s: MSHR %s\n", __func__
, tgt_pkt
->print());
2548 CacheBlk
*blk
= tags
->findBlock(mshr
->blkAddr
, mshr
->isSecure
);
2550 if (tgt_pkt
->cmd
== MemCmd::HardPFReq
&& forwardSnoops
) {
2551 // we should never have hardware prefetches to allocated
2553 assert(blk
== nullptr);
2555 // We need to check the caches above us to verify that
2556 // they don't have a copy of this block in the dirty state
2557 // at the moment. Without this check we could get a stale
2558 // copy from memory that might get used in place of the
2560 Packet
snoop_pkt(tgt_pkt
, true, false);
2561 snoop_pkt
.setExpressSnoop();
2562 // We are sending this packet upwards, but if it hits we will
2563 // get a snoop response that we end up treating just like a
2564 // normal response, hence it needs the MSHR as its sender
2566 snoop_pkt
.senderState
= mshr
;
2567 cpuSidePort
->sendTimingSnoopReq(&snoop_pkt
);
2569 // Check to see if the prefetch was squashed by an upper cache (to
2570 // prevent us from grabbing the line) or if a Check to see if a
2571 // writeback arrived between the time the prefetch was placed in
2572 // the MSHRs and when it was selected to be sent or if the
2573 // prefetch was squashed by an upper cache.
2575 // It is important to check cacheResponding before
2576 // prefetchSquashed. If another cache has committed to
2577 // responding, it will be sending a dirty response which will
2578 // arrive at the MSHR allocated for this request. Checking the
2579 // prefetchSquash first may result in the MSHR being
2580 // prematurely deallocated.
2581 if (snoop_pkt
.cacheResponding()) {
2582 auto M5_VAR_USED r
= outstandingSnoop
.insert(snoop_pkt
.req
);
2585 // if we are getting a snoop response with no sharers it
2586 // will be allocated as Modified
2587 bool pending_modified_resp
= !snoop_pkt
.hasSharers();
2588 markInService(mshr
, pending_modified_resp
);
2590 DPRINTF(Cache
, "Upward snoop of prefetch for addr"
2592 tgt_pkt
->getAddr(), tgt_pkt
->isSecure()? "s": "ns");
2596 if (snoop_pkt
.isBlockCached()) {
2597 DPRINTF(Cache
, "Block present, prefetch squashed by cache. "
2598 "Deallocating mshr target %#x.\n",
2601 // Deallocate the mshr target
2602 if (mshrQueue
.forceDeallocateTarget(mshr
)) {
2603 // Clear block if this deallocation resulted freed an
2604 // mshr when all had previously been utilized
2605 clearBlocked(Blocked_NoMSHRs
);
2608 // given that no response is expected, delete Request and Packet
2609 delete tgt_pkt
->req
;
2616 // either a prefetch that is not present upstream, or a normal
2617 // MSHR request, proceed to get the packet to send downstream
2618 PacketPtr pkt
= createMissPacket(tgt_pkt
, blk
, mshr
->needsWritable());
2620 mshr
->isForward
= (pkt
== nullptr);
2622 if (mshr
->isForward
) {
2623 // not a cache block request, but a response is expected
2624 // make copy of current packet to forward, keep current
2625 // copy for response handling
2626 pkt
= new Packet(tgt_pkt
, false, true);
2627 assert(!pkt
->isWrite());
2630 // play it safe and append (rather than set) the sender state,
2631 // as forwarded packets may already have existing state
2632 pkt
->pushSenderState(mshr
);
2634 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
2635 // A cache clean opearation is looking for a dirty block. Mark
2636 // the packet so that the destination xbar can determine that
2637 // there will be a follow-up write packet as well.
2638 pkt
->setSatisfied();
2641 if (!memSidePort
->sendTimingReq(pkt
)) {
2642 // we are awaiting a retry, but we
2643 // delete the packet and will be creating a new packet
2644 // when we get the opportunity
2647 // note that we have now masked any requestBus and
2648 // schedSendEvent (we will wait for a retry before
2649 // doing anything), and this is so even if we do not
2650 // care about this packet and might override it before
2654 // As part of the call to sendTimingReq the packet is
2655 // forwarded to all neighbouring caches (and any caches
2656 // above them) as a snoop. Thus at this point we know if
2657 // any of the neighbouring caches are responding, and if
2658 // so, we know it is dirty, and we can determine if it is
2659 // being passed as Modified, making our MSHR the ordering
2661 bool pending_modified_resp
= !pkt
->hasSharers() &&
2662 pkt
->cacheResponding();
2663 markInService(mshr
, pending_modified_resp
);
2664 if (pkt
->isClean() && blk
&& blk
->isDirty()) {
2665 // A cache clean opearation is looking for a dirty
2666 // block. If a dirty block is encountered a WriteClean
2667 // will update any copies to the path to the memory
2668 // until the point of reference.
2669 DPRINTF(CacheVerbose
, "%s: packet %s found block: %s\n",
2670 __func__
, pkt
->print(), blk
->print());
2671 PacketPtr wb_pkt
= writecleanBlk(blk
, pkt
->req
->getDest(),
2673 PacketList writebacks
;
2674 writebacks
.push_back(wb_pkt
);
2675 doWritebacks(writebacks
, 0);
2683 Cache::sendWriteQueuePacket(WriteQueueEntry
* wq_entry
)
2687 // always a single target for write queue entries
2688 PacketPtr tgt_pkt
= wq_entry
->getTarget()->pkt
;
2690 DPRINTF(Cache
, "%s: write %s\n", __func__
, tgt_pkt
->print());
2692 // forward as is, both for evictions and uncacheable writes
2693 if (!memSidePort
->sendTimingReq(tgt_pkt
)) {
2694 // note that we have now masked any requestBus and
2695 // schedSendEvent (we will wait for a retry before
2696 // doing anything), and this is so even if we do not
2697 // care about this packet and might override it before
2701 markInService(wq_entry
);
2707 Cache::serialize(CheckpointOut
&cp
) const
2709 bool dirty(isDirty());
2712 warn("*** The cache still contains dirty data. ***\n");
2713 warn(" Make sure to drain the system using the correct flags.\n");
2714 warn(" This checkpoint will not restore correctly and dirty data "
2715 " in the cache will be lost!\n");
2718 // Since we don't checkpoint the data in the cache, any dirty data
2719 // will be lost when restoring from a checkpoint of a system that
2720 // wasn't drained properly. Flag the checkpoint as invalid if the
2721 // cache contains dirty data.
2722 bool bad_checkpoint(dirty
);
2723 SERIALIZE_SCALAR(bad_checkpoint
);
2727 Cache::unserialize(CheckpointIn
&cp
)
2729 bool bad_checkpoint
;
2730 UNSERIALIZE_SCALAR(bad_checkpoint
);
2731 if (bad_checkpoint
) {
2732 fatal("Restoring from checkpoints with dirty caches is not supported "
2733 "in the classic memory system. Please remove any caches or "
2734 " drain them properly before taking checkpoints.\n");
2745 Cache::CpuSidePort::getAddrRanges() const
2747 return cache
->getAddrRanges();
2751 Cache::CpuSidePort::tryTiming(PacketPtr pkt
)
2753 assert(!cache
->system
->bypassCaches());
2755 // always let express snoop packets through if even if blocked
2756 if (pkt
->isExpressSnoop()) {
2758 } else if (isBlocked() || mustSendRetry
) {
2759 // either already committed to send a retry, or blocked
2760 mustSendRetry
= true;
2763 mustSendRetry
= false;
2768 Cache::CpuSidePort::recvTimingReq(PacketPtr pkt
)
2770 assert(!cache
->system
->bypassCaches());
2772 // always let express snoop packets through if even if blocked
2773 if (pkt
->isExpressSnoop()) {
2774 bool M5_VAR_USED bypass_success
= cache
->recvTimingReq(pkt
);
2775 assert(bypass_success
);
2779 return tryTiming(pkt
) && cache
->recvTimingReq(pkt
);
2783 Cache::CpuSidePort::recvAtomic(PacketPtr pkt
)
2785 return cache
->recvAtomic(pkt
);
2789 Cache::CpuSidePort::recvFunctional(PacketPtr pkt
)
2791 // functional request
2792 cache
->functionalAccess(pkt
, true);
2796 CpuSidePort::CpuSidePort(const std::string
&_name
, Cache
*_cache
,
2797 const std::string
&_label
)
2798 : BaseCache::CacheSlavePort(_name
, _cache
, _label
), cache(_cache
)
2803 CacheParams::create()
2806 assert(replacement_policy
);
2808 return new Cache(this);
2817 Cache::MemSidePort::recvTimingResp(PacketPtr pkt
)
2819 cache
->recvTimingResp(pkt
);
2823 // Express snooping requests to memside port
2825 Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt
)
2827 // handle snooping requests
2828 cache
->recvTimingSnoopReq(pkt
);
2832 Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt
)
2834 return cache
->recvAtomicSnoop(pkt
);
2838 Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt
)
2840 // functional snoop (note that in contrast to atomic we don't have
2841 // a specific functionalSnoop method, as they have the same
2842 // behaviour regardless)
2843 cache
->functionalAccess(pkt
, false);
2847 Cache::CacheReqPacketQueue::sendDeferredPacket()
2850 assert(!waitingOnRetry
);
2852 // there should never be any deferred request packets in the
2853 // queue, instead we resly on the cache to provide the packets
2854 // from the MSHR queue or write queue
2855 assert(deferredPacketReadyTime() == MaxTick
);
2857 // check for request packets (requests & writebacks)
2858 QueueEntry
* entry
= cache
.getNextQueueEntry();
2861 // can happen if e.g. we attempt a writeback and fail, but
2862 // before the retry, the writeback is eliminated because
2863 // we snoop another cache's ReadEx.
2865 // let our snoop responses go first if there are responses to
2866 // the same addresses
2867 if (checkConflictingSnoop(entry
->blkAddr
)) {
2870 waitingOnRetry
= entry
->sendPacket(cache
);
2873 // if we succeeded and are not waiting for a retry, schedule the
2874 // next send considering when the next queue is ready, note that
2875 // snoop responses have their own packet queue and thus schedule
2877 if (!waitingOnRetry
) {
2878 schedSendEvent(cache
.nextQueueReadyTime());
2883 MemSidePort::MemSidePort(const std::string
&_name
, Cache
*_cache
,
2884 const std::string
&_label
)
2885 : BaseCache::CacheMasterPort(_name
, _cache
, _reqQueue
, _snoopRespQueue
),
2886 _reqQueue(*_cache
, *this, _snoopRespQueue
, _label
),
2887 _snoopRespQueue(*_cache
, *this, _label
), cache(_cache
)