summaryrefslogtreecommitdiff
path: root/src/mem/cache/cache_impl.hh
blob: 58eb0bdbcf31494bf76442be8a76bdc1694d111a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
/*
 * Copyright (c) 2002-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Erik Hallnor
 *          Dave Greene
 *          Nathan Binkert
 */

/**
 * @file
 * Cache definitions.
 */

#include <assert.h>
#include <math.h>

#include <cassert>
#include <iostream>
#include <string>

#include "sim/host.hh"
#include "base/misc.hh"
#include "cpu/smt.hh"

#include "mem/cache/cache.hh"
#include "mem/cache/cache_blk.hh"
#include "mem/cache/miss/mshr.hh"
#include "mem/cache/prefetch/prefetcher.hh"

#include "sim/sim_exit.hh" // for SimExitEvent

template<class TagStore, class Buffering, class Coherence>
bool
Cache<TagStore,Buffering,Coherence>::
doTimingAccess(Packet *pkt, CachePort *cachePort, bool isCpuSide)
{
    if (isCpuSide)
    {
        if (pkt->isWrite() && (pkt->req->isLocked())) {
            pkt->req->setScResult(1);
        }
        access(pkt);

    }
    else
    {
        if (pkt->isResponse())
            handleResponse(pkt);
        else {
            //Check if we should do the snoop
            if (pkt->flags & SNOOP_COMMIT)
                snoop(pkt);
        }
    }
    return true;
}

template<class TagStore, class Buffering, class Coherence>
Tick
Cache<TagStore,Buffering,Coherence>::
doAtomicAccess(Packet *pkt, bool isCpuSide)
{
    if (isCpuSide)
    {
        //Temporary solution to LL/SC
        if (pkt->isWrite() && (pkt->req->isLocked())) {
            pkt->req->setScResult(1);
        }

        probe(pkt, true, NULL);
        //TEMP ALWAYS SUCCES FOR NOW
        pkt->result = Packet::Success;
    }
    else
    {
        if (pkt->isResponse())
            handleResponse(pkt);
        else
            snoopProbe(pkt);
    }
    //Fix this timing info
    return hitLatency;
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::
doFunctionalAccess(Packet *pkt, bool isCpuSide)
{
    if (isCpuSide)
    {
        //TEMP USE CPU?THREAD 0 0
        pkt->req->setThreadContext(0,0);

        //Temporary solution to LL/SC
        if (pkt->isWrite() && (pkt->req->isLocked())) {
            assert("Can't handle LL/SC on functional path\n");
        }

        probe(pkt, false, memSidePort);
        //TEMP ALWAYS SUCCESFUL FOR NOW
        pkt->result = Packet::Success;
    }
    else
    {
            probe(pkt, false, cpuSidePort);
    }
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::
recvStatusChange(Port::Status status, bool isCpuSide)
{

}


template<class TagStore, class Buffering, class Coherence>
Cache<TagStore,Buffering,Coherence>::
Cache(const std::string &_name,
      Cache<TagStore,Buffering,Coherence>::Params &params)
    : BaseCache(_name, params.baseParams),
      prefetchAccess(params.prefetchAccess),
      tags(params.tags), missQueue(params.missQueue),
      coherence(params.coherence), prefetcher(params.prefetcher),
      doCopy(params.doCopy), blockOnCopy(params.blockOnCopy)
{
//FIX BUS POINTERS
//    if (params.in == NULL) {
        topLevelCache = true;
//    }
//PLEASE FIX THIS, BUS SIZES NOT BEING USED
        tags->setCache(this, blkSize, 1/*params.out->width, params.out->clockRate*/);
    tags->setPrefetcher(prefetcher);
    missQueue->setCache(this);
    missQueue->setPrefetcher(prefetcher);
    coherence->setCache(this);
    prefetcher->setCache(this);
    prefetcher->setTags(tags);
    prefetcher->setBuffer(missQueue);
    invalidateReq = new Request((Addr) NULL, blkSize, 0);
    invalidatePkt = new Packet(invalidateReq, Packet::InvalidateReq, 0);
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::regStats()
{
    BaseCache::regStats();
    tags->regStats(name());
    missQueue->regStats(name());
    coherence->regStats(name());
    prefetcher->regStats(name());
}

template<class TagStore, class Buffering, class Coherence>
bool
Cache<TagStore,Buffering,Coherence>::access(PacketPtr &pkt)
{
//@todo Add back in MemDebug Calls
//    MemDebug::cacheAccess(pkt);
    BlkType *blk = NULL;
    PacketList writebacks;
    int size = blkSize;
    int lat = hitLatency;
    if (prefetchAccess) {
        //We are determining prefetches on access stream, call prefetcher
        prefetcher->handleMiss(pkt, curTick);
    }
    if (!pkt->req->isUncacheable()) {
        blk = tags->handleAccess(pkt, lat, writebacks);
    } else {
        size = pkt->getSize();
    }
    // If this is a block size write/hint (WH64) allocate the block here
    // if the coherence protocol allows it.
    /** @todo make the fast write alloc (wh64) work with coherence. */
    /** @todo Do we want to do fast writes for writebacks as well? */
    if (!blk && pkt->getSize() >= blkSize && coherence->allowFastWrites() &&
        (pkt->cmd == Packet::WriteReq || pkt->cmd == Packet::WriteInvalidateReq) ) {
        // not outstanding misses, can do this
        MSHR* outstanding_miss = missQueue->findMSHR(pkt->getAddr());
        if (pkt->cmd == Packet::WriteInvalidateReq || !outstanding_miss) {
            if (outstanding_miss) {
                warn("WriteInv doing a fastallocate"
                     "with an outstanding miss to the same address\n");
            }
            blk = tags->handleFill(NULL, pkt, BlkValid | BlkWritable,
                                   writebacks);
            ++fastWrites;
        }
    }
    while (!writebacks.empty()) {
        missQueue->doWriteback(writebacks.front());
        writebacks.pop_front();
    }
    DPRINTF(Cache, "%s %x %s blk_addr: %x\n", pkt->cmdString(),
            pkt->getAddr() & (((ULL(1))<<48)-1), (blk) ? "hit" : "miss",
            pkt->getAddr() & ~((Addr)blkSize - 1));
    if (blk) {
        // Hit
        hits[pkt->cmdToIndex()][0/*pkt->req->getThreadNum()*/]++;
        // clear dirty bit if write through
        if (pkt->needsResponse())
            respond(pkt, curTick+lat);
        if (pkt->cmd == Packet::Writeback) {
            //Signal that you can kill the pkt/req
            pkt->flags |= SATISFIED;
        }
        return true;
    }

    // Miss
    if (!pkt->req->isUncacheable()) {
        misses[pkt->cmdToIndex()][0/*pkt->req->getThreadNum()*/]++;
        /** @todo Move miss count code into BaseCache */
        if (missCount) {
            --missCount;
            if (missCount == 0)
                exitSimLoop("A cache reached the maximum miss count");
        }
    }
    missQueue->handleMiss(pkt, size, curTick + hitLatency);
//    return MA_CACHE_MISS;
    return true;
}


template<class TagStore, class Buffering, class Coherence>
Packet *
Cache<TagStore,Buffering,Coherence>::getPacket()
{
    assert(missQueue->havePending());
    Packet * pkt = missQueue->getPacket();
    if (pkt) {
        if (!pkt->req->isUncacheable()) {
            if (pkt->cmd == Packet::HardPFReq) misses[Packet::HardPFReq][0/*pkt->req->getThreadNum()*/]++;
            BlkType *blk = tags->findBlock(pkt);
            Packet::Command cmd = coherence->getBusCmd(pkt->cmd,
                                              (blk)? blk->status : 0);
            missQueue->setBusCmd(pkt, cmd);
        }
    }

    assert(!doMasterRequest() || missQueue->havePending());
    assert(!pkt || pkt->time <= curTick);
    return pkt;
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::sendResult(PacketPtr &pkt, MSHR* mshr, bool success)
{
    if (success && !(pkt->flags & NACKED_LINE)) {
        missQueue->markInService(pkt, mshr);
        //Temp Hack for UPGRADES
        if (pkt->cmd == Packet::UpgradeReq) {
            pkt->flags &= ~CACHE_LINE_FILL;
            BlkType *blk = tags->findBlock(pkt);
            CacheBlk::State old_state = (blk) ? blk->status : 0;
            CacheBlk::State new_state = coherence->getNewState(pkt,old_state);
            DPRINTF(Cache, "Block for blk addr %x moving from state %i to %i\n",
                    pkt->getAddr() & (((ULL(1))<<48)-1), old_state, new_state);
            //Set the state on the upgrade
            memcpy(pkt->getPtr<uint8_t>(), blk->data, blkSize);
            PacketList writebacks;
            tags->handleFill(blk, mshr, new_state, writebacks, pkt);
            assert(writebacks.empty());
            missQueue->handleResponse(pkt, curTick + hitLatency);
        }
    } else if (pkt && !pkt->req->isUncacheable()) {
        pkt->flags &= ~NACKED_LINE;
        pkt->flags &= ~SATISFIED;
        pkt->flags &= ~SNOOP_COMMIT;
        missQueue->restoreOrigCmd(pkt);
    }
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::handleResponse(Packet * &pkt)
{
    BlkType *blk = NULL;
    if (pkt->senderState) {
        if (pkt->result == Packet::Nacked) {
            //pkt->reinitFromRequest();
            warn("NACKs from devices not connected to the same bus not implemented\n");
            return;
        }
        if (pkt->result == Packet::BadAddress) {
            //Make the response a Bad address and send it
        }
//	MemDebug::cacheResponse(pkt);
        DPRINTF(Cache, "Handling reponse to %x, blk addr: %x\n",pkt->getAddr(),
                pkt->getAddr() & (((ULL(1))<<48)-1));

        if (pkt->isCacheFill() && !pkt->isNoAllocate()) {
            blk = tags->findBlock(pkt);
            CacheBlk::State old_state = (blk) ? blk->status : 0;
            PacketList writebacks;
            CacheBlk::State new_state = coherence->getNewState(pkt,old_state);
            DPRINTF(Cache, "Block for blk addr %x moving from state %i to %i\n",
                    pkt->getAddr() & (((ULL(1))<<48)-1), old_state, new_state);
            blk = tags->handleFill(blk, (MSHR*)pkt->senderState,
                                   new_state, writebacks, pkt);
            while (!writebacks.empty()) {
                    missQueue->doWriteback(writebacks.front());
                    writebacks.pop_front();
            }
        }
        missQueue->handleResponse(pkt, curTick + hitLatency);
    }
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::pseudoFill(Addr addr)
{
    // Need to temporarily move this blk into MSHRs
    MSHR *mshr = missQueue->allocateTargetList(addr);
    int lat;
    PacketList dummy;
    // Read the data into the mshr
    BlkType *blk = tags->handleAccess(mshr->pkt, lat, dummy, false);
    assert(dummy.empty());
    assert(mshr->pkt->flags & SATISFIED);
    // can overload order since it isn't used on non pending blocks
    mshr->order = blk->status;
    // temporarily remove the block from the cache.
    tags->invalidateBlk(addr);
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::pseudoFill(MSHR *mshr)
{
    // Need to temporarily move this blk into MSHRs
    assert(mshr->pkt->cmd == Packet::ReadReq);
    int lat;
    PacketList dummy;
    // Read the data into the mshr
    BlkType *blk = tags->handleAccess(mshr->pkt, lat, dummy, false);
    assert(dummy.empty());
    assert(mshr->pkt->flags & SATISFIED);
    // can overload order since it isn't used on non pending blocks
    mshr->order = blk->status;
    // temporarily remove the block from the cache.
    tags->invalidateBlk(mshr->pkt->getAddr());
}


template<class TagStore, class Buffering, class Coherence>
Packet *
Cache<TagStore,Buffering,Coherence>::getCoherencePacket()
{
    return coherence->getPacket();
}


template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::snoop(Packet * &pkt)
{
    Addr blk_addr = pkt->getAddr() & ~(Addr(blkSize-1));
    BlkType *blk = tags->findBlock(pkt);
    MSHR *mshr = missQueue->findMSHR(blk_addr);
    if (isTopLevel() && coherence->hasProtocol()) { //@todo Move this into handle bus req
        //If we find an mshr, and it is in service, we need to NACK or invalidate
        if (mshr) {
            if (mshr->inService) {
                if ((mshr->pkt->isInvalidate() || !mshr->pkt->isCacheFill())
                    && (pkt->cmd != Packet::InvalidateReq && pkt->cmd != Packet::WriteInvalidateReq)) {
                    //If the outstanding request was an invalidate (upgrade,readex,..)
                    //Then we need to ACK the request until we get the data
                    //Also NACK if the outstanding request is not a cachefill (writeback)
                    assert(!(pkt->flags & SATISFIED));
                    pkt->flags |= SATISFIED;
                    pkt->flags |= NACKED_LINE;
                    ///@todo NACK's from other levels
                    //warn("NACKs from devices not connected to the same bus not implemented\n");
                    //respondToSnoop(pkt, curTick + hitLatency);
                    return;
                }
                else {
                    //The supplier will be someone else, because we are waiting for
                    //the data.  This should cause this cache to be forced to go to
                    //the shared state, not the exclusive even though the shared line
                    //won't be asserted.  But for now we will just invlidate ourselves
                    //and allow the other cache to go into the exclusive state.
                    //@todo Make it so a read to a pending read doesn't invalidate.
                    //@todo Make it so that a read to a pending read can't be exclusive now.

                    //Set the address so find match works
                    //panic("Don't have invalidates yet\n");
                    invalidatePkt->addrOverride(pkt->getAddr());

                    //Append the invalidate on
                    missQueue->addTarget(mshr,invalidatePkt);
                    DPRINTF(Cache, "Appending Invalidate to blk_addr: %x\n", pkt->getAddr() & (((ULL(1))<<48)-1));
                    return;
                }
            }
        }
        //We also need to check the writeback buffers and handle those
        std::vector<MSHR *> writebacks;
        if (missQueue->findWrites(blk_addr, writebacks)) {
            DPRINTF(Cache, "Snoop hit in writeback to blk_addr: %x\n", pkt->getAddr() & (((ULL(1))<<48)-1));

            //Look through writebacks for any non-uncachable writes, use that
            for (int i=0; i<writebacks.size(); i++) {
                mshr = writebacks[i];

                if (!mshr->pkt->req->isUncacheable()) {
                    if (pkt->isRead()) {
                        //Only Upgrades don't get here
                        //Supply the data
                        assert(!(pkt->flags & SATISFIED));
                        pkt->flags |= SATISFIED;

                        //If we are in an exclusive protocol, make it ask again
                        //to get write permissions (upgrade), signal shared
                        pkt->flags |= SHARED_LINE;

                        assert(pkt->isRead());
                        Addr offset = pkt->getAddr() & (blkSize - 1);
                        assert(offset < blkSize);
                        assert(pkt->getSize() <= blkSize);
                        assert(offset + pkt->getSize() <=blkSize);
                        memcpy(pkt->getPtr<uint8_t>(), mshr->pkt->getPtr<uint8_t>() + offset, pkt->getSize());

                        respondToSnoop(pkt, curTick + hitLatency);
                    }

                    if (pkt->isInvalidate()) {
                        //This must be an upgrade or other cache will take ownership
                        missQueue->markInService(mshr->pkt, mshr);
                    }
                    return;
                }
            }
        }
    }
    CacheBlk::State new_state;
    bool satisfy = coherence->handleBusRequest(pkt,blk,mshr, new_state);
    if (satisfy) {
        DPRINTF(Cache, "Cache snooped a %s request for addr %x and now supplying data,"
                "new state is %i\n",
                pkt->cmdString(), blk_addr, new_state);

        tags->handleSnoop(blk, new_state, pkt);
        respondToSnoop(pkt, curTick + hitLatency);
        return;
    }
    if (blk) DPRINTF(Cache, "Cache snooped a %s request for addr %x, new state is %i\n",
                     pkt->cmdString(), blk_addr, new_state);
    tags->handleSnoop(blk, new_state);
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::snoopResponse(Packet * &pkt)
{
    //Need to handle the response, if NACKED
    if (pkt->flags & NACKED_LINE) {
        //Need to mark it as not in service, and retry for bus
        assert(0); //Yeah, we saw a NACK come through

        //For now this should never get called, we return false when we see a NACK
        //instead, by doing this we allow the bus_blocked mechanism to handle the retry
        //For now it retrys in just 2 cycles, need to figure out how to change that
        //Eventually we will want to also have success come in as a parameter
        //Need to make sure that we handle the functionality that happens on successufl
        //return of the sendAddr function
    }
}

template<class TagStore, class Buffering, class Coherence>
void
Cache<TagStore,Buffering,Coherence>::invalidateBlk(Addr addr)
{
    tags->invalidateBlk(addr);
}


/**
 * @todo Fix to not assume write allocate
 */
template<class TagStore, class Buffering, class Coherence>
Tick
Cache<TagStore,Buffering,Coherence>::probe(Packet * &pkt, bool update, CachePort* otherSidePort)
{
//    MemDebug::cacheProbe(pkt);
    if (!pkt->req->isUncacheable()) {
        if (pkt->isInvalidate() && !pkt->isRead()
            && !pkt->isWrite()) {
            //Upgrade or Invalidate, satisfy it, don't forward
            DPRINTF(Cache, "%s %x ? blk_addr: %x\n", pkt->cmdString(),
                    pkt->getAddr() & (((ULL(1))<<48)-1),
                    pkt->getAddr() & ~((Addr)blkSize - 1));
            pkt->flags |= SATISFIED;
            return 0;
        }
    }

    PacketList writebacks;
    int lat;
    BlkType *blk = tags->handleAccess(pkt, lat, writebacks, update);

    if (!blk) {
        // Need to check for outstanding misses and writes
        Addr blk_addr = pkt->getAddr() & ~(blkSize - 1);

        // There can only be one matching outstanding miss.
        MSHR* mshr = missQueue->findMSHR(blk_addr);

        // There can be many matching outstanding writes.
        std::vector<MSHR*> writes;
        missQueue->findWrites(blk_addr, writes);

        if (!update) {
                otherSidePort->sendFunctional(pkt);

            // Check for data in MSHR and writebuffer.
            if (mshr) {
                warn("Found outstanding miss on an non-update probe");
                MSHR::TargetList *targets = mshr->getTargetList();
                MSHR::TargetList::iterator i = targets->begin();
                MSHR::TargetList::iterator end = targets->end();
                for (; i != end; ++i) {
                    Packet * target = *i;
                    // If the target contains data, and it overlaps the
                    // probed request, need to update data
                    if (target->isWrite() && target->intersect(pkt)) {
                        uint8_t* pkt_data;
                        uint8_t* write_data;
                        int data_size;
                        if (target->getAddr() < pkt->getAddr()) {
                            int offset = pkt->getAddr() - target->getAddr();
                            pkt_data = pkt->getPtr<uint8_t>();
                            write_data = target->getPtr<uint8_t>() + offset;
                            data_size = target->getSize() - offset;
                            assert(data_size > 0);
                            if (data_size > pkt->getSize())
                                data_size = pkt->getSize();
                        } else {
                            int offset = target->getAddr() - pkt->getAddr();
                            pkt_data = pkt->getPtr<uint8_t>() + offset;
                            write_data = target->getPtr<uint8_t>();
                            data_size = pkt->getSize() - offset;
                            assert(data_size > pkt->getSize());
                            if (data_size > target->getSize())
                                data_size = target->getSize();
                        }

                        if (pkt->isWrite()) {
                            memcpy(pkt_data, write_data, data_size);
                        } else {
                            memcpy(write_data, pkt_data, data_size);
                        }
                    }
                }
            }
            for (int i = 0; i < writes.size(); ++i) {
                Packet * write = writes[i]->pkt;
                if (write->intersect(pkt)) {
                    warn("Found outstanding write on an non-update probe");
                    uint8_t* pkt_data;
                    uint8_t* write_data;
                    int data_size;
                    if (write->getAddr() < pkt->getAddr()) {
                        int offset = pkt->getAddr() - write->getAddr();
                        pkt_data = pkt->getPtr<uint8_t>();
                        write_data = write->getPtr<uint8_t>() + offset;
                        data_size = write->getSize() - offset;
                        assert(data_size > 0);
                        if (data_size > pkt->getSize())
                            data_size = pkt->getSize();
                    } else {
                        int offset = write->getAddr() - pkt->getAddr();
                        pkt_data = pkt->getPtr<uint8_t>() + offset;
                        write_data = write->getPtr<uint8_t>();
                        data_size = pkt->getSize() - offset;
                        assert(data_size > pkt->getSize());
                        if (data_size > write->getSize())
                            data_size = write->getSize();
                    }

                    if (pkt->isWrite()) {
                        memcpy(pkt_data, write_data, data_size);
                    } else {
                        memcpy(write_data, pkt_data, data_size);
                    }

                }
            }
            return 0;
        } else {
            // update the cache state and statistics
            if (mshr || !writes.empty()){
                // Can't handle it, return pktuest unsatisfied.
                panic("Atomic access ran into outstanding MSHR's or WB's!");
            }
            if (!pkt->req->isUncacheable()) {
                // Fetch the cache block to fill
                BlkType *blk = tags->findBlock(pkt);
                Packet::Command temp_cmd = coherence->getBusCmd(pkt->cmd,
                                                   (blk)? blk->status : 0);

                Packet * busPkt = new Packet(pkt->req,temp_cmd, -1, blkSize);

                busPkt->allocate();

                busPkt->time = curTick;

                lat = memSidePort->sendAtomic(busPkt);

                //Be sure to flip the response to a request for coherence
                if (busPkt->needsResponse()) {
                    busPkt->makeAtomicResponse();
                }

/*		if (!(busPkt->flags & SATISFIED)) {
                    // blocked at a higher level, just return
                    return 0;
                }

*/		misses[pkt->cmdToIndex()][0/*pkt->req->getThreadNum()*/]++;

                CacheBlk::State old_state = (blk) ? blk->status : 0;
                tags->handleFill(blk, busPkt,
                                 coherence->getNewState(busPkt, old_state),
                                 writebacks, pkt);
                // Handle writebacks if needed
                while (!writebacks.empty()){
                    memSidePort->sendAtomic(writebacks.front());
                    writebacks.pop_front();
                }
                return lat + hitLatency;
            } else {
                return memSidePort->sendAtomic(pkt);
            }
        }
    } else {
        // There was a cache hit.
        // Handle writebacks if needed
        while (!writebacks.empty()){
            memSidePort->sendAtomic(writebacks.front());
            writebacks.pop_front();
        }

        if (update) {
            hits[pkt->cmdToIndex()][0/*pkt->req->getThreadNum()*/]++;
        } else if (pkt->isWrite()) {
            // Still need to change data in all locations.
            otherSidePort->sendFunctional(pkt);
        }
        return curTick + lat;
    }
    fatal("Probe not handled.\n");
    return 0;
}

template<class TagStore, class Buffering, class Coherence>
Tick
Cache<TagStore,Buffering,Coherence>::snoopProbe(PacketPtr &pkt)
{
        Addr blk_addr = pkt->getAddr() & ~(Addr(blkSize-1));
        BlkType *blk = tags->findBlock(pkt);
        MSHR *mshr = missQueue->findMSHR(blk_addr);
        CacheBlk::State new_state = 0;
        bool satisfy = coherence->handleBusRequest(pkt,blk,mshr, new_state);
        if (satisfy) {
            DPRINTF(Cache, "Cache snooped a %s request for addr %x and now supplying data,"
                    "new state is %i\n",
                    pkt->cmdString(), blk_addr, new_state);

            tags->handleSnoop(blk, new_state, pkt);
            return hitLatency;
        }
        if (blk) DPRINTF(Cache, "Cache snooped a %s request for addr %x, new state is %i\n",
                     pkt->cmdString(), blk_addr, new_state);
        tags->handleSnoop(blk, new_state);
        return 0;
}