1/*
2 * Copyright (c) 2002-2005 The Regents of The University of Michigan
3 * Copyright (c) 2010 Advanced Micro Devices, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Erik Hallnor
30 * Dave Greene
31 */
32
33/**
34 * @file
35 * Miss Status and Handling Register (MSHR) definitions.
36 */
37
38#include <algorithm>
39#include <cassert>
40#include <string>
41#include <vector>
42
43#include "base/misc.hh"
44#include "base/types.hh"
| 1/*
2 * Copyright (c) 2002-2005 The Regents of The University of Michigan
3 * Copyright (c) 2010 Advanced Micro Devices, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Erik Hallnor
30 * Dave Greene
31 */
32
33/**
34 * @file
35 * Miss Status and Handling Register (MSHR) definitions.
36 */
37
38#include <algorithm>
39#include <cassert>
40#include <string>
41#include <vector>
42
43#include "base/misc.hh"
44#include "base/types.hh"
|
45#include "mem/cache/cache.hh"
46#include "mem/cache/mshr.hh"
47#include "sim/core.hh"
48
49using namespace std;
50
51MSHR::MSHR()
52{
53 inService = false;
54 ntargets = 0;
55 threadNum = InvalidThreadID;
56 targets = new TargetList();
57 deferredTargets = new TargetList();
58}
59
60
61MSHR::TargetList::TargetList()
62 : needsExclusive(false), hasUpgrade(false)
63{}
64
65
66inline void
67MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
68 Counter order, Target::Source source, bool markPending)
69{
70 if (source != Target::FromSnoop) {
71 if (pkt->needsExclusive()) {
72 needsExclusive = true;
73 }
74
75 // StoreCondReq is effectively an upgrade if it's in an MSHR
76 // since it would have been failed already if we didn't have a
77 // read-only copy
78 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
79 hasUpgrade = true;
80 }
81 }
82
83 if (markPending) {
84 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
85 if (mshr != NULL) {
86 assert(!mshr->downstreamPending);
87 mshr->downstreamPending = true;
88 }
89 }
90
91 push_back(Target(pkt, readyTime, order, source, markPending));
92}
93
94
95static void
96replaceUpgrade(PacketPtr pkt)
97{
98 if (pkt->cmd == MemCmd::UpgradeReq) {
99 pkt->cmd = MemCmd::ReadExReq;
100 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
101 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
102 pkt->cmd = MemCmd::SCUpgradeFailReq;
103 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
104 } else if (pkt->cmd == MemCmd::StoreCondReq) {
105 pkt->cmd = MemCmd::StoreCondFailReq;
106 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
107 }
108}
109
110
111void
112MSHR::TargetList::replaceUpgrades()
113{
114 if (!hasUpgrade)
115 return;
116
117 Iterator end_i = end();
118 for (Iterator i = begin(); i != end_i; ++i) {
119 replaceUpgrade(i->pkt);
120 }
121
122 hasUpgrade = false;
123}
124
125
126void
127MSHR::TargetList::clearDownstreamPending()
128{
129 Iterator end_i = end();
130 for (Iterator i = begin(); i != end_i; ++i) {
131 if (i->markedPending) {
132 MSHR *mshr = dynamic_cast<MSHR*>(i->pkt->senderState);
133 if (mshr != NULL) {
134 mshr->clearDownstreamPending();
135 }
136 }
137 }
138}
139
140
141bool
142MSHR::TargetList::checkFunctional(PacketPtr pkt)
143{
144 Iterator end_i = end();
145 for (Iterator i = begin(); i != end_i; ++i) {
146 if (pkt->checkFunctional(i->pkt)) {
147 return true;
148 }
149 }
150
151 return false;
152}
153
154
155void
156MSHR::TargetList::
157print(std::ostream &os, int verbosity, const std::string &prefix) const
158{
159 ConstIterator end_i = end();
160 for (ConstIterator i = begin(); i != end_i; ++i) {
161 const char *s;
162 switch (i->source) {
163 case Target::FromCPU: s = "FromCPU";
164 case Target::FromSnoop: s = "FromSnoop";
165 case Target::FromPrefetcher: s = "FromPrefetcher";
166 default: s = "";
167 }
168 ccprintf(os, "%s%s: ", prefix, s);
169 i->pkt->print(os, verbosity, "");
170 }
171}
172
173
174void
175MSHR::allocate(Addr _addr, int _size, PacketPtr target,
176 Tick whenReady, Counter _order)
177{
178 addr = _addr;
179 size = _size;
180 readyTime = whenReady;
181 order = _order;
182 assert(target);
183 isForward = false;
184 _isUncacheable = target->req->isUncacheable();
185 inService = false;
186 downstreamPending = false;
187 threadNum = 0;
188 ntargets = 1;
189 assert(targets->isReset());
190 // Don't know of a case where we would allocate a new MSHR for a
191 // snoop (mem-side request), so set source according to request here
192 Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
193 Target::FromPrefetcher : Target::FromCPU;
194 targets->add(target, whenReady, _order, source, true);
195 assert(deferredTargets->isReset());
196 data = NULL;
197}
198
199
200void
201MSHR::clearDownstreamPending()
202{
203 assert(downstreamPending);
204 downstreamPending = false;
205 // recursively clear flag on any MSHRs we will be forwarding
206 // responses to
207 targets->clearDownstreamPending();
208}
209
210bool
211MSHR::markInService(PacketPtr pkt)
212{
213 assert(!inService);
214 if (isForwardNoResponse()) {
215 // we just forwarded the request packet & don't expect a
216 // response, so get rid of it
217 assert(getNumTargets() == 1);
218 popTarget();
219 return true;
220 }
221 inService = true;
222 pendingDirty = (targets->needsExclusive ||
223 (!pkt->sharedAsserted() && pkt->memInhibitAsserted()));
224 postInvalidate = postDowngrade = false;
225
226 if (!downstreamPending) {
227 // let upstream caches know that the request has made it to a
228 // level where it's going to get a response
229 targets->clearDownstreamPending();
230 }
231 return false;
232}
233
234
235void
236MSHR::deallocate()
237{
238 assert(targets->empty());
239 targets->resetFlags();
240 assert(deferredTargets->isReset());
241 assert(ntargets == 0);
242 inService = false;
243}
244
245/*
246 * Adds a target to an MSHR
247 */
248void
249MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
250{
251 // if there's a request already in service for this MSHR, we will
252 // have to defer the new target until after the response if any of
253 // the following are true:
254 // - there are other targets already deferred
255 // - there's a pending invalidate to be applied after the response
256 // comes back (but before this target is processed)
257 // - this target requires an exclusive block and either we're not
258 // getting an exclusive block back or we have already snooped
259 // another read request that will downgrade our exclusive block
260 // to shared
261
262 // assume we'd never issue a prefetch when we've got an
263 // outstanding miss
264 assert(pkt->cmd != MemCmd::HardPFReq);
265
266 if (inService &&
267 (!deferredTargets->empty() || hasPostInvalidate() ||
268 (pkt->needsExclusive() &&
269 (!isPendingDirty() || hasPostDowngrade() || isForward)))) {
270 // need to put on deferred list
271 if (hasPostInvalidate())
272 replaceUpgrade(pkt);
273 deferredTargets->add(pkt, whenReady, _order, Target::FromCPU, true);
274 } else {
275 // No request outstanding, or still OK to append to
276 // outstanding request: append to regular target list. Only
277 // mark pending if current request hasn't been issued yet
278 // (isn't in service).
279 targets->add(pkt, whenReady, _order, Target::FromCPU, !inService);
280 }
281
282 ++ntargets;
283}
284
285bool
286MSHR::handleSnoop(PacketPtr pkt, Counter _order)
287{
288 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
289 // Request has not been issued yet, or it's been issued
290 // locally but is buffered unissued at some downstream cache
291 // which is forwarding us this snoop. Either way, the packet
292 // we're snooping logically precedes this MSHR's request, so
293 // the snoop has no impact on the MSHR, but must be processed
294 // in the standard way by the cache. The only exception is
295 // that if we're an L2+ cache buffering an UpgradeReq from a
296 // higher-level cache, and the snoop is invalidating, then our
297 // buffered upgrades must be converted to read exclusives,
298 // since the upper-level cache no longer has a valid copy.
299 // That is, even though the upper-level cache got out on its
300 // local bus first, some other invalidating transaction
301 // reached the global bus before the upgrade did.
302 if (pkt->needsExclusive()) {
303 targets->replaceUpgrades();
304 deferredTargets->replaceUpgrades();
305 }
306
307 return false;
308 }
309
310 // From here on down, the request issued by this MSHR logically
311 // precedes the request we're snooping.
312 if (pkt->needsExclusive()) {
313 // snooped request still precedes the re-request we'll have to
314 // issue for deferred targets, if any...
315 deferredTargets->replaceUpgrades();
316 }
317
318 if (hasPostInvalidate()) {
319 // a prior snoop has already appended an invalidation, so
320 // logically we don't have the block anymore; no need for
321 // further snooping.
322 return true;
323 }
324
325 if (isPendingDirty() || pkt->isInvalidate()) {
326 // We need to save and replay the packet in two cases:
327 // 1. We're awaiting an exclusive copy, so ownership is pending,
328 // and we need to respond after we receive data.
329 // 2. It's an invalidation (e.g., UpgradeReq), and we need
330 // to forward the snoop up the hierarchy after the current
331 // transaction completes.
332
333 // Actual target device (typ. PhysicalMemory) will delete the
334 // packet on reception, so we need to save a copy here.
335 PacketPtr cp_pkt = new Packet(pkt, true);
336 targets->add(cp_pkt, curTick(), _order, Target::FromSnoop,
337 downstreamPending && targets->needsExclusive);
338 ++ntargets;
339
340 if (isPendingDirty()) {
341 pkt->assertMemInhibit();
342 pkt->setSupplyExclusive();
343 }
344
345 if (pkt->needsExclusive()) {
346 // This transaction will take away our pending copy
347 postInvalidate = true;
348 }
349 }
350
351 if (!pkt->needsExclusive()) {
352 // This transaction will get a read-shared copy, downgrading
353 // our copy if we had an exclusive one
354 postDowngrade = true;
355 pkt->assertShared();
356 }
357
358 return true;
359}
360
361
362bool
363MSHR::promoteDeferredTargets()
364{
365 assert(targets->empty());
366 if (deferredTargets->empty()) {
367 return false;
368 }
369
370 // swap targets & deferredTargets lists
371 TargetList *tmp = targets;
372 targets = deferredTargets;
373 deferredTargets = tmp;
374
375 assert(targets->size() == ntargets);
376
377 // clear deferredTargets flags
378 deferredTargets->resetFlags();
379
380 order = targets->front().order;
381 readyTime = std::max(curTick(), targets->front().readyTime);
382
383 return true;
384}
385
386
387void
388MSHR::handleFill(Packet *pkt, CacheBlk *blk)
389{
390 if (!pkt->sharedAsserted()
391 && !(hasPostInvalidate() || hasPostDowngrade())
392 && deferredTargets->needsExclusive) {
393 // We got an exclusive response, but we have deferred targets
394 // which are waiting to request an exclusive copy (not because
395 // of a pending invalidate). This can happen if the original
396 // request was for a read-only (non-exclusive) block, but we
397 // got an exclusive copy anyway because of the E part of the
398 // MOESI/MESI protocol. Since we got the exclusive copy
399 // there's no need to defer the targets, so move them up to
400 // the regular target list.
401 assert(!targets->needsExclusive);
402 targets->needsExclusive = true;
403 // if any of the deferred targets were upper-level cache
404 // requests marked downstreamPending, need to clear that
405 assert(!downstreamPending); // not pending here anymore
406 deferredTargets->clearDownstreamPending();
407 // this clears out deferredTargets too
408 targets->splice(targets->end(), *deferredTargets);
409 deferredTargets->resetFlags();
410 }
411}
412
413
414bool
415MSHR::checkFunctional(PacketPtr pkt)
416{
417 // For printing, we treat the MSHR as a whole as single entity.
418 // For other requests, we iterate over the individual targets
419 // since that's where the actual data lies.
420 if (pkt->isPrint()) {
421 pkt->checkFunctional(this, addr, size, NULL);
422 return false;
423 } else {
424 return (targets->checkFunctional(pkt) ||
425 deferredTargets->checkFunctional(pkt));
426 }
427}
428
429
430void
431MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
432{
433 ccprintf(os, "%s[%x:%x] %s %s %s state: %s %s %s %s\n",
434 prefix, addr, addr+size-1,
435 isForward ? "Forward" : "",
436 isForwardNoResponse() ? "ForwNoResp" : "",
437 needsExclusive() ? "Excl" : "",
438 _isUncacheable ? "Unc" : "",
439 inService ? "InSvc" : "",
440 downstreamPending ? "DwnPend" : "",
441 hasPostInvalidate() ? "PostInv" : "",
442 hasPostDowngrade() ? "PostDowngr" : "");
443
444 ccprintf(os, "%s Targets:\n", prefix);
445 targets->print(os, verbosity, prefix + " ");
446 if (!deferredTargets->empty()) {
447 ccprintf(os, "%s Deferred Targets:\n", prefix);
448 deferredTargets->print(os, verbosity, prefix + " ");
449 }
450}
451
452MSHR::~MSHR()
453{
454}
| 46#include "mem/cache/cache.hh"
47#include "mem/cache/mshr.hh"
48#include "sim/core.hh"
49
50using namespace std;
51
52MSHR::MSHR()
53{
54 inService = false;
55 ntargets = 0;
56 threadNum = InvalidThreadID;
57 targets = new TargetList();
58 deferredTargets = new TargetList();
59}
60
61
62MSHR::TargetList::TargetList()
63 : needsExclusive(false), hasUpgrade(false)
64{}
65
66
67inline void
68MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
69 Counter order, Target::Source source, bool markPending)
70{
71 if (source != Target::FromSnoop) {
72 if (pkt->needsExclusive()) {
73 needsExclusive = true;
74 }
75
76 // StoreCondReq is effectively an upgrade if it's in an MSHR
77 // since it would have been failed already if we didn't have a
78 // read-only copy
79 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
80 hasUpgrade = true;
81 }
82 }
83
84 if (markPending) {
85 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
86 if (mshr != NULL) {
87 assert(!mshr->downstreamPending);
88 mshr->downstreamPending = true;
89 }
90 }
91
92 push_back(Target(pkt, readyTime, order, source, markPending));
93}
94
95
96static void
97replaceUpgrade(PacketPtr pkt)
98{
99 if (pkt->cmd == MemCmd::UpgradeReq) {
100 pkt->cmd = MemCmd::ReadExReq;
101 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
102 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
103 pkt->cmd = MemCmd::SCUpgradeFailReq;
104 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
105 } else if (pkt->cmd == MemCmd::StoreCondReq) {
106 pkt->cmd = MemCmd::StoreCondFailReq;
107 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
108 }
109}
110
111
112void
113MSHR::TargetList::replaceUpgrades()
114{
115 if (!hasUpgrade)
116 return;
117
118 Iterator end_i = end();
119 for (Iterator i = begin(); i != end_i; ++i) {
120 replaceUpgrade(i->pkt);
121 }
122
123 hasUpgrade = false;
124}
125
126
127void
128MSHR::TargetList::clearDownstreamPending()
129{
130 Iterator end_i = end();
131 for (Iterator i = begin(); i != end_i; ++i) {
132 if (i->markedPending) {
133 MSHR *mshr = dynamic_cast<MSHR*>(i->pkt->senderState);
134 if (mshr != NULL) {
135 mshr->clearDownstreamPending();
136 }
137 }
138 }
139}
140
141
142bool
143MSHR::TargetList::checkFunctional(PacketPtr pkt)
144{
145 Iterator end_i = end();
146 for (Iterator i = begin(); i != end_i; ++i) {
147 if (pkt->checkFunctional(i->pkt)) {
148 return true;
149 }
150 }
151
152 return false;
153}
154
155
156void
157MSHR::TargetList::
158print(std::ostream &os, int verbosity, const std::string &prefix) const
159{
160 ConstIterator end_i = end();
161 for (ConstIterator i = begin(); i != end_i; ++i) {
162 const char *s;
163 switch (i->source) {
164 case Target::FromCPU: s = "FromCPU";
165 case Target::FromSnoop: s = "FromSnoop";
166 case Target::FromPrefetcher: s = "FromPrefetcher";
167 default: s = "";
168 }
169 ccprintf(os, "%s%s: ", prefix, s);
170 i->pkt->print(os, verbosity, "");
171 }
172}
173
174
175void
176MSHR::allocate(Addr _addr, int _size, PacketPtr target,
177 Tick whenReady, Counter _order)
178{
179 addr = _addr;
180 size = _size;
181 readyTime = whenReady;
182 order = _order;
183 assert(target);
184 isForward = false;
185 _isUncacheable = target->req->isUncacheable();
186 inService = false;
187 downstreamPending = false;
188 threadNum = 0;
189 ntargets = 1;
190 assert(targets->isReset());
191 // Don't know of a case where we would allocate a new MSHR for a
192 // snoop (mem-side request), so set source according to request here
193 Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
194 Target::FromPrefetcher : Target::FromCPU;
195 targets->add(target, whenReady, _order, source, true);
196 assert(deferredTargets->isReset());
197 data = NULL;
198}
199
200
201void
202MSHR::clearDownstreamPending()
203{
204 assert(downstreamPending);
205 downstreamPending = false;
206 // recursively clear flag on any MSHRs we will be forwarding
207 // responses to
208 targets->clearDownstreamPending();
209}
210
211bool
212MSHR::markInService(PacketPtr pkt)
213{
214 assert(!inService);
215 if (isForwardNoResponse()) {
216 // we just forwarded the request packet & don't expect a
217 // response, so get rid of it
218 assert(getNumTargets() == 1);
219 popTarget();
220 return true;
221 }
222 inService = true;
223 pendingDirty = (targets->needsExclusive ||
224 (!pkt->sharedAsserted() && pkt->memInhibitAsserted()));
225 postInvalidate = postDowngrade = false;
226
227 if (!downstreamPending) {
228 // let upstream caches know that the request has made it to a
229 // level where it's going to get a response
230 targets->clearDownstreamPending();
231 }
232 return false;
233}
234
235
236void
237MSHR::deallocate()
238{
239 assert(targets->empty());
240 targets->resetFlags();
241 assert(deferredTargets->isReset());
242 assert(ntargets == 0);
243 inService = false;
244}
245
246/*
247 * Adds a target to an MSHR
248 */
249void
250MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
251{
252 // if there's a request already in service for this MSHR, we will
253 // have to defer the new target until after the response if any of
254 // the following are true:
255 // - there are other targets already deferred
256 // - there's a pending invalidate to be applied after the response
257 // comes back (but before this target is processed)
258 // - this target requires an exclusive block and either we're not
259 // getting an exclusive block back or we have already snooped
260 // another read request that will downgrade our exclusive block
261 // to shared
262
263 // assume we'd never issue a prefetch when we've got an
264 // outstanding miss
265 assert(pkt->cmd != MemCmd::HardPFReq);
266
267 if (inService &&
268 (!deferredTargets->empty() || hasPostInvalidate() ||
269 (pkt->needsExclusive() &&
270 (!isPendingDirty() || hasPostDowngrade() || isForward)))) {
271 // need to put on deferred list
272 if (hasPostInvalidate())
273 replaceUpgrade(pkt);
274 deferredTargets->add(pkt, whenReady, _order, Target::FromCPU, true);
275 } else {
276 // No request outstanding, or still OK to append to
277 // outstanding request: append to regular target list. Only
278 // mark pending if current request hasn't been issued yet
279 // (isn't in service).
280 targets->add(pkt, whenReady, _order, Target::FromCPU, !inService);
281 }
282
283 ++ntargets;
284}
285
286bool
287MSHR::handleSnoop(PacketPtr pkt, Counter _order)
288{
289 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
290 // Request has not been issued yet, or it's been issued
291 // locally but is buffered unissued at some downstream cache
292 // which is forwarding us this snoop. Either way, the packet
293 // we're snooping logically precedes this MSHR's request, so
294 // the snoop has no impact on the MSHR, but must be processed
295 // in the standard way by the cache. The only exception is
296 // that if we're an L2+ cache buffering an UpgradeReq from a
297 // higher-level cache, and the snoop is invalidating, then our
298 // buffered upgrades must be converted to read exclusives,
299 // since the upper-level cache no longer has a valid copy.
300 // That is, even though the upper-level cache got out on its
301 // local bus first, some other invalidating transaction
302 // reached the global bus before the upgrade did.
303 if (pkt->needsExclusive()) {
304 targets->replaceUpgrades();
305 deferredTargets->replaceUpgrades();
306 }
307
308 return false;
309 }
310
311 // From here on down, the request issued by this MSHR logically
312 // precedes the request we're snooping.
313 if (pkt->needsExclusive()) {
314 // snooped request still precedes the re-request we'll have to
315 // issue for deferred targets, if any...
316 deferredTargets->replaceUpgrades();
317 }
318
319 if (hasPostInvalidate()) {
320 // a prior snoop has already appended an invalidation, so
321 // logically we don't have the block anymore; no need for
322 // further snooping.
323 return true;
324 }
325
326 if (isPendingDirty() || pkt->isInvalidate()) {
327 // We need to save and replay the packet in two cases:
328 // 1. We're awaiting an exclusive copy, so ownership is pending,
329 // and we need to respond after we receive data.
330 // 2. It's an invalidation (e.g., UpgradeReq), and we need
331 // to forward the snoop up the hierarchy after the current
332 // transaction completes.
333
334 // Actual target device (typ. PhysicalMemory) will delete the
335 // packet on reception, so we need to save a copy here.
336 PacketPtr cp_pkt = new Packet(pkt, true);
337 targets->add(cp_pkt, curTick(), _order, Target::FromSnoop,
338 downstreamPending && targets->needsExclusive);
339 ++ntargets;
340
341 if (isPendingDirty()) {
342 pkt->assertMemInhibit();
343 pkt->setSupplyExclusive();
344 }
345
346 if (pkt->needsExclusive()) {
347 // This transaction will take away our pending copy
348 postInvalidate = true;
349 }
350 }
351
352 if (!pkt->needsExclusive()) {
353 // This transaction will get a read-shared copy, downgrading
354 // our copy if we had an exclusive one
355 postDowngrade = true;
356 pkt->assertShared();
357 }
358
359 return true;
360}
361
362
363bool
364MSHR::promoteDeferredTargets()
365{
366 assert(targets->empty());
367 if (deferredTargets->empty()) {
368 return false;
369 }
370
371 // swap targets & deferredTargets lists
372 TargetList *tmp = targets;
373 targets = deferredTargets;
374 deferredTargets = tmp;
375
376 assert(targets->size() == ntargets);
377
378 // clear deferredTargets flags
379 deferredTargets->resetFlags();
380
381 order = targets->front().order;
382 readyTime = std::max(curTick(), targets->front().readyTime);
383
384 return true;
385}
386
387
388void
389MSHR::handleFill(Packet *pkt, CacheBlk *blk)
390{
391 if (!pkt->sharedAsserted()
392 && !(hasPostInvalidate() || hasPostDowngrade())
393 && deferredTargets->needsExclusive) {
394 // We got an exclusive response, but we have deferred targets
395 // which are waiting to request an exclusive copy (not because
396 // of a pending invalidate). This can happen if the original
397 // request was for a read-only (non-exclusive) block, but we
398 // got an exclusive copy anyway because of the E part of the
399 // MOESI/MESI protocol. Since we got the exclusive copy
400 // there's no need to defer the targets, so move them up to
401 // the regular target list.
402 assert(!targets->needsExclusive);
403 targets->needsExclusive = true;
404 // if any of the deferred targets were upper-level cache
405 // requests marked downstreamPending, need to clear that
406 assert(!downstreamPending); // not pending here anymore
407 deferredTargets->clearDownstreamPending();
408 // this clears out deferredTargets too
409 targets->splice(targets->end(), *deferredTargets);
410 deferredTargets->resetFlags();
411 }
412}
413
414
415bool
416MSHR::checkFunctional(PacketPtr pkt)
417{
418 // For printing, we treat the MSHR as a whole as single entity.
419 // For other requests, we iterate over the individual targets
420 // since that's where the actual data lies.
421 if (pkt->isPrint()) {
422 pkt->checkFunctional(this, addr, size, NULL);
423 return false;
424 } else {
425 return (targets->checkFunctional(pkt) ||
426 deferredTargets->checkFunctional(pkt));
427 }
428}
429
430
431void
432MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
433{
434 ccprintf(os, "%s[%x:%x] %s %s %s state: %s %s %s %s\n",
435 prefix, addr, addr+size-1,
436 isForward ? "Forward" : "",
437 isForwardNoResponse() ? "ForwNoResp" : "",
438 needsExclusive() ? "Excl" : "",
439 _isUncacheable ? "Unc" : "",
440 inService ? "InSvc" : "",
441 downstreamPending ? "DwnPend" : "",
442 hasPostInvalidate() ? "PostInv" : "",
443 hasPostDowngrade() ? "PostDowngr" : "");
444
445 ccprintf(os, "%s Targets:\n", prefix);
446 targets->print(os, verbosity, prefix + " ");
447 if (!deferredTargets->empty()) {
448 ccprintf(os, "%s Deferred Targets:\n", prefix);
449 deferredTargets->print(os, verbosity, prefix + " ");
450 }
451}
452
453MSHR::~MSHR()
454{
455}
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