1/*
2 * Copyright (c) 2012-2013 ARM Limited
3 * All rights reserved.
4 *
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.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
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.
28 *
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.
40 *
41 * Authors: Erik Hallnor
42 * Dave Greene
43 */
44
45/**
46 * @file
47 * Miss Status and Handling Register (MSHR) definitions.
48 */
49
50#include <algorithm>
51#include <cassert>
52#include <string>
53#include <vector>
54
55#include "base/misc.hh"
56#include "base/types.hh"
57#include "debug/Cache.hh"
58#include "mem/cache/cache.hh"
59#include "mem/cache/mshr.hh"
60#include "sim/core.hh"
61
62using namespace std;
63
64MSHR::MSHR() : readyTime(0), _isUncacheable(false), downstreamPending(false),
65 pendingDirty(false),
66 postInvalidate(false), postDowngrade(false),
67 queue(NULL), order(0), addr(0),
68 size(0), isSecure(false), inService(false),
69 isForward(false), threadNum(InvalidThreadID), data(NULL)
70{
71}
72
73
74MSHR::TargetList::TargetList()
75 : needsExclusive(false), hasUpgrade(false)
76{}
77
78
79inline void
80MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
81 Counter order, Target::Source source, bool markPending)
82{
83 if (source != Target::FromSnoop) {
84 if (pkt->needsExclusive()) {
85 needsExclusive = true;
86 }
87
88 // StoreCondReq is effectively an upgrade if it's in an MSHR
89 // since it would have been failed already if we didn't have a
90 // read-only copy
91 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
92 hasUpgrade = true;
93 }
94 }
95
96 if (markPending) {
97 // Iterate over the SenderState stack and see if we find
98 // an MSHR entry. If we do, set the downstreamPending
99 // flag. Otherwise, do nothing.
100 MSHR *mshr = pkt->findNextSenderState<MSHR>();
101 if (mshr != NULL) {
102 assert(!mshr->downstreamPending);
103 mshr->downstreamPending = true;
104 }
105 }
106
107 push_back(Target(pkt, readyTime, order, source, markPending));
108}
109
110
111static void
112replaceUpgrade(PacketPtr pkt)
113{
114 if (pkt->cmd == MemCmd::UpgradeReq) {
115 pkt->cmd = MemCmd::ReadExReq;
116 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
117 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
118 pkt->cmd = MemCmd::SCUpgradeFailReq;
119 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
120 } else if (pkt->cmd == MemCmd::StoreCondReq) {
121 pkt->cmd = MemCmd::StoreCondFailReq;
122 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
123 }
124}
125
126
127void
128MSHR::TargetList::replaceUpgrades()
129{
130 if (!hasUpgrade)
131 return;
132
133 Iterator end_i = end();
134 for (Iterator i = begin(); i != end_i; ++i) {
135 replaceUpgrade(i->pkt);
136 }
137
138 hasUpgrade = false;
139}
140
141
142void
143MSHR::TargetList::clearDownstreamPending()
144{
145 Iterator end_i = end();
146 for (Iterator i = begin(); i != end_i; ++i) {
147 if (i->markedPending) {
148 // Iterate over the SenderState stack and see if we find
149 // an MSHR entry. If we find one, clear the
150 // downstreamPending flag by calling
151 // clearDownstreamPending(). This recursively clears the
152 // downstreamPending flag in all caches this packet has
153 // passed through.
154 MSHR *mshr = i->pkt->findNextSenderState<MSHR>();
155 if (mshr != NULL) {
156 mshr->clearDownstreamPending();
157 }
158 }
159 }
160}
161
162
163bool
164MSHR::TargetList::checkFunctional(PacketPtr pkt)
165{
166 Iterator end_i = end();
167 for (Iterator i = begin(); i != end_i; ++i) {
168 if (pkt->checkFunctional(i->pkt)) {
169 return true;
170 }
171 }
172
173 return false;
174}
175
176
177void
178MSHR::TargetList::
179print(std::ostream &os, int verbosity, const std::string &prefix) const
180{
181 ConstIterator end_i = end();
182 for (ConstIterator i = begin(); i != end_i; ++i) {
183 const char *s;
184 switch (i->source) {
185 case Target::FromCPU:
186 s = "FromCPU";
187 break;
188 case Target::FromSnoop:
189 s = "FromSnoop";
190 break;
191 case Target::FromPrefetcher:
192 s = "FromPrefetcher";
193 break;
194 default:
195 s = "";
196 break;
197 }
198 ccprintf(os, "%s%s: ", prefix, s);
199 i->pkt->print(os, verbosity, "");
200 }
201}
202
203
204void
205MSHR::allocate(Addr _addr, int _size, PacketPtr target, Tick whenReady,
206 Counter _order)
207{
208 addr = _addr;
209 size = _size;
210 isSecure = target->isSecure();
211 readyTime = whenReady;
212 order = _order;
213 assert(target);
214 isForward = false;
215 _isUncacheable = target->req->isUncacheable();
216 inService = false;
217 downstreamPending = false;
218 threadNum = 0;
219 assert(targets.isReset());
220 // Don't know of a case where we would allocate a new MSHR for a
221 // snoop (mem-side request), so set source according to request here
222 Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
223 Target::FromPrefetcher : Target::FromCPU;
224 targets.add(target, whenReady, _order, source, true);
225 assert(deferredTargets.isReset());
226 data = NULL;
227}
228
229
230void
231MSHR::clearDownstreamPending()
232{
233 assert(downstreamPending);
234 downstreamPending = false;
235 // recursively clear flag on any MSHRs we will be forwarding
236 // responses to
237 targets.clearDownstreamPending();
238}
239
240bool
| 1/*
2 * Copyright (c) 2012-2013 ARM Limited
3 * All rights reserved.
4 *
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.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
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.
28 *
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.
40 *
41 * Authors: Erik Hallnor
42 * Dave Greene
43 */
44
45/**
46 * @file
47 * Miss Status and Handling Register (MSHR) definitions.
48 */
49
50#include <algorithm>
51#include <cassert>
52#include <string>
53#include <vector>
54
55#include "base/misc.hh"
56#include "base/types.hh"
57#include "debug/Cache.hh"
58#include "mem/cache/cache.hh"
59#include "mem/cache/mshr.hh"
60#include "sim/core.hh"
61
62using namespace std;
63
64MSHR::MSHR() : readyTime(0), _isUncacheable(false), downstreamPending(false),
65 pendingDirty(false),
66 postInvalidate(false), postDowngrade(false),
67 queue(NULL), order(0), addr(0),
68 size(0), isSecure(false), inService(false),
69 isForward(false), threadNum(InvalidThreadID), data(NULL)
70{
71}
72
73
74MSHR::TargetList::TargetList()
75 : needsExclusive(false), hasUpgrade(false)
76{}
77
78
79inline void
80MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
81 Counter order, Target::Source source, bool markPending)
82{
83 if (source != Target::FromSnoop) {
84 if (pkt->needsExclusive()) {
85 needsExclusive = true;
86 }
87
88 // StoreCondReq is effectively an upgrade if it's in an MSHR
89 // since it would have been failed already if we didn't have a
90 // read-only copy
91 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
92 hasUpgrade = true;
93 }
94 }
95
96 if (markPending) {
97 // Iterate over the SenderState stack and see if we find
98 // an MSHR entry. If we do, set the downstreamPending
99 // flag. Otherwise, do nothing.
100 MSHR *mshr = pkt->findNextSenderState<MSHR>();
101 if (mshr != NULL) {
102 assert(!mshr->downstreamPending);
103 mshr->downstreamPending = true;
104 }
105 }
106
107 push_back(Target(pkt, readyTime, order, source, markPending));
108}
109
110
111static void
112replaceUpgrade(PacketPtr pkt)
113{
114 if (pkt->cmd == MemCmd::UpgradeReq) {
115 pkt->cmd = MemCmd::ReadExReq;
116 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
117 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
118 pkt->cmd = MemCmd::SCUpgradeFailReq;
119 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
120 } else if (pkt->cmd == MemCmd::StoreCondReq) {
121 pkt->cmd = MemCmd::StoreCondFailReq;
122 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
123 }
124}
125
126
127void
128MSHR::TargetList::replaceUpgrades()
129{
130 if (!hasUpgrade)
131 return;
132
133 Iterator end_i = end();
134 for (Iterator i = begin(); i != end_i; ++i) {
135 replaceUpgrade(i->pkt);
136 }
137
138 hasUpgrade = false;
139}
140
141
142void
143MSHR::TargetList::clearDownstreamPending()
144{
145 Iterator end_i = end();
146 for (Iterator i = begin(); i != end_i; ++i) {
147 if (i->markedPending) {
148 // Iterate over the SenderState stack and see if we find
149 // an MSHR entry. If we find one, clear the
150 // downstreamPending flag by calling
151 // clearDownstreamPending(). This recursively clears the
152 // downstreamPending flag in all caches this packet has
153 // passed through.
154 MSHR *mshr = i->pkt->findNextSenderState<MSHR>();
155 if (mshr != NULL) {
156 mshr->clearDownstreamPending();
157 }
158 }
159 }
160}
161
162
163bool
164MSHR::TargetList::checkFunctional(PacketPtr pkt)
165{
166 Iterator end_i = end();
167 for (Iterator i = begin(); i != end_i; ++i) {
168 if (pkt->checkFunctional(i->pkt)) {
169 return true;
170 }
171 }
172
173 return false;
174}
175
176
177void
178MSHR::TargetList::
179print(std::ostream &os, int verbosity, const std::string &prefix) const
180{
181 ConstIterator end_i = end();
182 for (ConstIterator i = begin(); i != end_i; ++i) {
183 const char *s;
184 switch (i->source) {
185 case Target::FromCPU:
186 s = "FromCPU";
187 break;
188 case Target::FromSnoop:
189 s = "FromSnoop";
190 break;
191 case Target::FromPrefetcher:
192 s = "FromPrefetcher";
193 break;
194 default:
195 s = "";
196 break;
197 }
198 ccprintf(os, "%s%s: ", prefix, s);
199 i->pkt->print(os, verbosity, "");
200 }
201}
202
203
204void
205MSHR::allocate(Addr _addr, int _size, PacketPtr target, Tick whenReady,
206 Counter _order)
207{
208 addr = _addr;
209 size = _size;
210 isSecure = target->isSecure();
211 readyTime = whenReady;
212 order = _order;
213 assert(target);
214 isForward = false;
215 _isUncacheable = target->req->isUncacheable();
216 inService = false;
217 downstreamPending = false;
218 threadNum = 0;
219 assert(targets.isReset());
220 // Don't know of a case where we would allocate a new MSHR for a
221 // snoop (mem-side request), so set source according to request here
222 Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
223 Target::FromPrefetcher : Target::FromCPU;
224 targets.add(target, whenReady, _order, source, true);
225 assert(deferredTargets.isReset());
226 data = NULL;
227}
228
229
230void
231MSHR::clearDownstreamPending()
232{
233 assert(downstreamPending);
234 downstreamPending = false;
235 // recursively clear flag on any MSHRs we will be forwarding
236 // responses to
237 targets.clearDownstreamPending();
238}
239
240bool
|
256 postInvalidate = postDowngrade = false;
257
258 if (!downstreamPending) {
259 // let upstream caches know that the request has made it to a
260 // level where it's going to get a response
261 targets.clearDownstreamPending();
262 }
263 return false;
264}
265
266
267void
268MSHR::deallocate()
269{
270 assert(targets.empty());
271 targets.resetFlags();
272 assert(deferredTargets.isReset());
273 inService = false;
274}
275
276/*
277 * Adds a target to an MSHR
278 */
279void
280MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
281{
282 // if there's a request already in service for this MSHR, we will
283 // have to defer the new target until after the response if any of
284 // the following are true:
285 // - there are other targets already deferred
286 // - there's a pending invalidate to be applied after the response
287 // comes back (but before this target is processed)
288 // - this target requires an exclusive block and either we're not
289 // getting an exclusive block back or we have already snooped
290 // another read request that will downgrade our exclusive block
291 // to shared
292
293 // assume we'd never issue a prefetch when we've got an
294 // outstanding miss
295 assert(pkt->cmd != MemCmd::HardPFReq);
296
297 if (inService &&
298 (!deferredTargets.empty() || hasPostInvalidate() ||
299 (pkt->needsExclusive() &&
300 (!isPendingDirty() || hasPostDowngrade() || isForward)))) {
301 // need to put on deferred list
302 if (hasPostInvalidate())
303 replaceUpgrade(pkt);
304 deferredTargets.add(pkt, whenReady, _order, Target::FromCPU, true);
305 } else {
306 // No request outstanding, or still OK to append to
307 // outstanding request: append to regular target list. Only
308 // mark pending if current request hasn't been issued yet
309 // (isn't in service).
310 targets.add(pkt, whenReady, _order, Target::FromCPU, !inService);
311 }
312}
313
314bool
315MSHR::handleSnoop(PacketPtr pkt, Counter _order)
316{
317 DPRINTF(Cache, "%s for %s address %x size %d\n", __func__,
318 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
319 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
320 // Request has not been issued yet, or it's been issued
321 // locally but is buffered unissued at some downstream cache
322 // which is forwarding us this snoop. Either way, the packet
323 // we're snooping logically precedes this MSHR's request, so
324 // the snoop has no impact on the MSHR, but must be processed
325 // in the standard way by the cache. The only exception is
326 // that if we're an L2+ cache buffering an UpgradeReq from a
327 // higher-level cache, and the snoop is invalidating, then our
328 // buffered upgrades must be converted to read exclusives,
329 // since the upper-level cache no longer has a valid copy.
330 // That is, even though the upper-level cache got out on its
331 // local bus first, some other invalidating transaction
332 // reached the global bus before the upgrade did.
333 if (pkt->needsExclusive()) {
334 targets.replaceUpgrades();
335 deferredTargets.replaceUpgrades();
336 }
337
338 return false;
339 }
340
341 // From here on down, the request issued by this MSHR logically
342 // precedes the request we're snooping.
343 if (pkt->needsExclusive()) {
344 // snooped request still precedes the re-request we'll have to
345 // issue for deferred targets, if any...
346 deferredTargets.replaceUpgrades();
347 }
348
349 if (hasPostInvalidate()) {
350 // a prior snoop has already appended an invalidation, so
351 // logically we don't have the block anymore; no need for
352 // further snooping.
353 return true;
354 }
355
356 if (isPendingDirty() || pkt->isInvalidate()) {
357 // We need to save and replay the packet in two cases:
358 // 1. We're awaiting an exclusive copy, so ownership is pending,
359 // and we need to respond after we receive data.
360 // 2. It's an invalidation (e.g., UpgradeReq), and we need
361 // to forward the snoop up the hierarchy after the current
362 // transaction completes.
363
364 // Actual target device (typ. a memory) will delete the
365 // packet on reception, so we need to save a copy here.
366
367 // Clear flags and also allocate new data as the original
368 // packet data storage may have been deleted by the time we
369 // get to send this packet.
370 PacketPtr cp_pkt = new Packet(pkt, true, true);
371 targets.add(cp_pkt, curTick(), _order, Target::FromSnoop,
372 downstreamPending && targets.needsExclusive);
373
374 if (isPendingDirty()) {
375 pkt->assertMemInhibit();
376 pkt->setSupplyExclusive();
377 }
378
379 if (pkt->needsExclusive()) {
380 // This transaction will take away our pending copy
381 postInvalidate = true;
382 }
383 }
384
385 if (!pkt->needsExclusive()) {
386 // This transaction will get a read-shared copy, downgrading
387 // our copy if we had an exclusive one
388 postDowngrade = true;
389 pkt->assertShared();
390 }
391
392 return true;
393}
394
395
396bool
397MSHR::promoteDeferredTargets()
398{
399 assert(targets.empty());
400 if (deferredTargets.empty()) {
401 return false;
402 }
403
404 // swap targets & deferredTargets lists
405 std::swap(targets, deferredTargets);
406
407 // clear deferredTargets flags
408 deferredTargets.resetFlags();
409
410 order = targets.front().order;
411 readyTime = std::max(curTick(), targets.front().readyTime);
412
413 return true;
414}
415
416
417void
418MSHR::handleFill(Packet *pkt, CacheBlk *blk)
419{
420 if (!pkt->sharedAsserted()
421 && !(hasPostInvalidate() || hasPostDowngrade())
422 && deferredTargets.needsExclusive) {
423 // We got an exclusive response, but we have deferred targets
424 // which are waiting to request an exclusive copy (not because
425 // of a pending invalidate). This can happen if the original
426 // request was for a read-only (non-exclusive) block, but we
427 // got an exclusive copy anyway because of the E part of the
428 // MOESI/MESI protocol. Since we got the exclusive copy
429 // there's no need to defer the targets, so move them up to
430 // the regular target list.
431 assert(!targets.needsExclusive);
432 targets.needsExclusive = true;
433 // if any of the deferred targets were upper-level cache
434 // requests marked downstreamPending, need to clear that
435 assert(!downstreamPending); // not pending here anymore
436 deferredTargets.clearDownstreamPending();
437 // this clears out deferredTargets too
438 targets.splice(targets.end(), deferredTargets);
439 deferredTargets.resetFlags();
440 }
441}
442
443
444bool
445MSHR::checkFunctional(PacketPtr pkt)
446{
447 // For printing, we treat the MSHR as a whole as single entity.
448 // For other requests, we iterate over the individual targets
449 // since that's where the actual data lies.
450 if (pkt->isPrint()) {
451 pkt->checkFunctional(this, addr, isSecure, size, NULL);
452 return false;
453 } else {
454 return (targets.checkFunctional(pkt) ||
455 deferredTargets.checkFunctional(pkt));
456 }
457}
458
459
460void
461MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
462{
463 ccprintf(os, "%s[%x:%x](%s) %s %s %s state: %s %s %s %s %s\n",
464 prefix, addr, addr+size-1,
465 isSecure ? "s" : "ns",
466 isForward ? "Forward" : "",
467 isForwardNoResponse() ? "ForwNoResp" : "",
468 needsExclusive() ? "Excl" : "",
469 _isUncacheable ? "Unc" : "",
470 inService ? "InSvc" : "",
471 downstreamPending ? "DwnPend" : "",
472 hasPostInvalidate() ? "PostInv" : "",
473 hasPostDowngrade() ? "PostDowngr" : "");
474
475 ccprintf(os, "%s Targets:\n", prefix);
476 targets.print(os, verbosity, prefix + " ");
477 if (!deferredTargets.empty()) {
478 ccprintf(os, "%s Deferred Targets:\n", prefix);
479 deferredTargets.print(os, verbosity, prefix + " ");
480 }
481}
482
483std::string
484MSHR::print() const
485{
486 ostringstream str;
487 print(str);
488 return str.str();
489}
| 254 postInvalidate = postDowngrade = false;
255
256 if (!downstreamPending) {
257 // let upstream caches know that the request has made it to a
258 // level where it's going to get a response
259 targets.clearDownstreamPending();
260 }
261 return false;
262}
263
264
265void
266MSHR::deallocate()
267{
268 assert(targets.empty());
269 targets.resetFlags();
270 assert(deferredTargets.isReset());
271 inService = false;
272}
273
274/*
275 * Adds a target to an MSHR
276 */
277void
278MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
279{
280 // if there's a request already in service for this MSHR, we will
281 // have to defer the new target until after the response if any of
282 // the following are true:
283 // - there are other targets already deferred
284 // - there's a pending invalidate to be applied after the response
285 // comes back (but before this target is processed)
286 // - this target requires an exclusive block and either we're not
287 // getting an exclusive block back or we have already snooped
288 // another read request that will downgrade our exclusive block
289 // to shared
290
291 // assume we'd never issue a prefetch when we've got an
292 // outstanding miss
293 assert(pkt->cmd != MemCmd::HardPFReq);
294
295 if (inService &&
296 (!deferredTargets.empty() || hasPostInvalidate() ||
297 (pkt->needsExclusive() &&
298 (!isPendingDirty() || hasPostDowngrade() || isForward)))) {
299 // need to put on deferred list
300 if (hasPostInvalidate())
301 replaceUpgrade(pkt);
302 deferredTargets.add(pkt, whenReady, _order, Target::FromCPU, true);
303 } else {
304 // No request outstanding, or still OK to append to
305 // outstanding request: append to regular target list. Only
306 // mark pending if current request hasn't been issued yet
307 // (isn't in service).
308 targets.add(pkt, whenReady, _order, Target::FromCPU, !inService);
309 }
310}
311
312bool
313MSHR::handleSnoop(PacketPtr pkt, Counter _order)
314{
315 DPRINTF(Cache, "%s for %s address %x size %d\n", __func__,
316 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
317 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
318 // Request has not been issued yet, or it's been issued
319 // locally but is buffered unissued at some downstream cache
320 // which is forwarding us this snoop. Either way, the packet
321 // we're snooping logically precedes this MSHR's request, so
322 // the snoop has no impact on the MSHR, but must be processed
323 // in the standard way by the cache. The only exception is
324 // that if we're an L2+ cache buffering an UpgradeReq from a
325 // higher-level cache, and the snoop is invalidating, then our
326 // buffered upgrades must be converted to read exclusives,
327 // since the upper-level cache no longer has a valid copy.
328 // That is, even though the upper-level cache got out on its
329 // local bus first, some other invalidating transaction
330 // reached the global bus before the upgrade did.
331 if (pkt->needsExclusive()) {
332 targets.replaceUpgrades();
333 deferredTargets.replaceUpgrades();
334 }
335
336 return false;
337 }
338
339 // From here on down, the request issued by this MSHR logically
340 // precedes the request we're snooping.
341 if (pkt->needsExclusive()) {
342 // snooped request still precedes the re-request we'll have to
343 // issue for deferred targets, if any...
344 deferredTargets.replaceUpgrades();
345 }
346
347 if (hasPostInvalidate()) {
348 // a prior snoop has already appended an invalidation, so
349 // logically we don't have the block anymore; no need for
350 // further snooping.
351 return true;
352 }
353
354 if (isPendingDirty() || pkt->isInvalidate()) {
355 // We need to save and replay the packet in two cases:
356 // 1. We're awaiting an exclusive copy, so ownership is pending,
357 // and we need to respond after we receive data.
358 // 2. It's an invalidation (e.g., UpgradeReq), and we need
359 // to forward the snoop up the hierarchy after the current
360 // transaction completes.
361
362 // Actual target device (typ. a memory) will delete the
363 // packet on reception, so we need to save a copy here.
364
365 // Clear flags and also allocate new data as the original
366 // packet data storage may have been deleted by the time we
367 // get to send this packet.
368 PacketPtr cp_pkt = new Packet(pkt, true, true);
369 targets.add(cp_pkt, curTick(), _order, Target::FromSnoop,
370 downstreamPending && targets.needsExclusive);
371
372 if (isPendingDirty()) {
373 pkt->assertMemInhibit();
374 pkt->setSupplyExclusive();
375 }
376
377 if (pkt->needsExclusive()) {
378 // This transaction will take away our pending copy
379 postInvalidate = true;
380 }
381 }
382
383 if (!pkt->needsExclusive()) {
384 // This transaction will get a read-shared copy, downgrading
385 // our copy if we had an exclusive one
386 postDowngrade = true;
387 pkt->assertShared();
388 }
389
390 return true;
391}
392
393
394bool
395MSHR::promoteDeferredTargets()
396{
397 assert(targets.empty());
398 if (deferredTargets.empty()) {
399 return false;
400 }
401
402 // swap targets & deferredTargets lists
403 std::swap(targets, deferredTargets);
404
405 // clear deferredTargets flags
406 deferredTargets.resetFlags();
407
408 order = targets.front().order;
409 readyTime = std::max(curTick(), targets.front().readyTime);
410
411 return true;
412}
413
414
415void
416MSHR::handleFill(Packet *pkt, CacheBlk *blk)
417{
418 if (!pkt->sharedAsserted()
419 && !(hasPostInvalidate() || hasPostDowngrade())
420 && deferredTargets.needsExclusive) {
421 // We got an exclusive response, but we have deferred targets
422 // which are waiting to request an exclusive copy (not because
423 // of a pending invalidate). This can happen if the original
424 // request was for a read-only (non-exclusive) block, but we
425 // got an exclusive copy anyway because of the E part of the
426 // MOESI/MESI protocol. Since we got the exclusive copy
427 // there's no need to defer the targets, so move them up to
428 // the regular target list.
429 assert(!targets.needsExclusive);
430 targets.needsExclusive = true;
431 // if any of the deferred targets were upper-level cache
432 // requests marked downstreamPending, need to clear that
433 assert(!downstreamPending); // not pending here anymore
434 deferredTargets.clearDownstreamPending();
435 // this clears out deferredTargets too
436 targets.splice(targets.end(), deferredTargets);
437 deferredTargets.resetFlags();
438 }
439}
440
441
442bool
443MSHR::checkFunctional(PacketPtr pkt)
444{
445 // For printing, we treat the MSHR as a whole as single entity.
446 // For other requests, we iterate over the individual targets
447 // since that's where the actual data lies.
448 if (pkt->isPrint()) {
449 pkt->checkFunctional(this, addr, isSecure, size, NULL);
450 return false;
451 } else {
452 return (targets.checkFunctional(pkt) ||
453 deferredTargets.checkFunctional(pkt));
454 }
455}
456
457
458void
459MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
460{
461 ccprintf(os, "%s[%x:%x](%s) %s %s %s state: %s %s %s %s %s\n",
462 prefix, addr, addr+size-1,
463 isSecure ? "s" : "ns",
464 isForward ? "Forward" : "",
465 isForwardNoResponse() ? "ForwNoResp" : "",
466 needsExclusive() ? "Excl" : "",
467 _isUncacheable ? "Unc" : "",
468 inService ? "InSvc" : "",
469 downstreamPending ? "DwnPend" : "",
470 hasPostInvalidate() ? "PostInv" : "",
471 hasPostDowngrade() ? "PostDowngr" : "");
472
473 ccprintf(os, "%s Targets:\n", prefix);
474 targets.print(os, verbosity, prefix + " ");
475 if (!deferredTargets.empty()) {
476 ccprintf(os, "%s Deferred Targets:\n", prefix);
477 deferredTargets.print(os, verbosity, prefix + " ");
478 }
479}
480
481std::string
482MSHR::print() const
483{
484 ostringstream str;
485 print(str);
486 return str.str();
487}
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