1/*
2 * Copyright (c) 2012-2013, 2015 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),
| 1/*
2 * Copyright (c) 2012-2013, 2015 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),
| 65 pendingModified(false),
|
66 postInvalidate(false), postDowngrade(false),
67 queue(NULL), order(0), blkAddr(0),
68 blkSize(0), isSecure(false), inService(false),
69 isForward(false), allocOnFill(false),
70 data(NULL)
71{
72}
73
74
75MSHR::TargetList::TargetList()
| 66 postInvalidate(false), postDowngrade(false),
67 queue(NULL), order(0), blkAddr(0),
68 blkSize(0), isSecure(false), inService(false),
69 isForward(false), allocOnFill(false),
70 data(NULL)
71{
72}
73
74
75MSHR::TargetList::TargetList()
|
76 : needsExclusive(false), hasUpgrade(false)
| 76 : needsWritable(false), hasUpgrade(false)
|
77{}
78
79
80inline void
81MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
82 Counter order, Target::Source source, bool markPending)
83{
84 if (source != Target::FromSnoop) {
| 77{}
78
79
80inline void
81MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
82 Counter order, Target::Source source, bool markPending)
83{
84 if (source != Target::FromSnoop) {
|
85 if (pkt->needsExclusive()) {
86 needsExclusive = true;
| 85 if (pkt->needsWritable()) {
86 needsWritable = true;
|
87 }
88
89 // StoreCondReq is effectively an upgrade if it's in an MSHR
90 // since it would have been failed already if we didn't have a
91 // read-only copy
92 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
93 hasUpgrade = true;
94 }
95 }
96
97 if (markPending) {
98 // Iterate over the SenderState stack and see if we find
99 // an MSHR entry. If we do, set the downstreamPending
100 // flag. Otherwise, do nothing.
101 MSHR *mshr = pkt->findNextSenderState<MSHR>();
102 if (mshr != NULL) {
103 assert(!mshr->downstreamPending);
104 mshr->downstreamPending = true;
105 } else {
106 // No need to clear downstreamPending later
107 markPending = false;
108 }
109 }
110
111 emplace_back(pkt, readyTime, order, source, markPending);
112}
113
114
115static void
116replaceUpgrade(PacketPtr pkt)
117{
118 if (pkt->cmd == MemCmd::UpgradeReq) {
119 pkt->cmd = MemCmd::ReadExReq;
120 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
121 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
122 pkt->cmd = MemCmd::SCUpgradeFailReq;
123 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
124 } else if (pkt->cmd == MemCmd::StoreCondReq) {
125 pkt->cmd = MemCmd::StoreCondFailReq;
126 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
127 }
128}
129
130
131void
132MSHR::TargetList::replaceUpgrades()
133{
134 if (!hasUpgrade)
135 return;
136
137 for (auto& t : *this) {
138 replaceUpgrade(t.pkt);
139 }
140
141 hasUpgrade = false;
142}
143
144
145void
146MSHR::TargetList::clearDownstreamPending()
147{
148 for (auto& t : *this) {
149 if (t.markedPending) {
150 // Iterate over the SenderState stack and see if we find
151 // an MSHR entry. If we find one, clear the
152 // downstreamPending flag by calling
153 // clearDownstreamPending(). This recursively clears the
154 // downstreamPending flag in all caches this packet has
155 // passed through.
156 MSHR *mshr = t.pkt->findNextSenderState<MSHR>();
157 if (mshr != NULL) {
158 mshr->clearDownstreamPending();
159 }
160 }
161 }
162}
163
164
165bool
166MSHR::TargetList::checkFunctional(PacketPtr pkt)
167{
168 for (auto& t : *this) {
169 if (pkt->checkFunctional(t.pkt)) {
170 return true;
171 }
172 }
173
174 return false;
175}
176
177
178void
179MSHR::TargetList::print(std::ostream &os, int verbosity,
180 const std::string &prefix) const
181{
182 for (auto& t : *this) {
183 const char *s;
184 switch (t.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 t.pkt->print(os, verbosity, "");
200 }
201}
202
203
204void
205MSHR::allocate(Addr blk_addr, unsigned blk_size, PacketPtr target,
206 Tick when_ready, Counter _order, bool alloc_on_fill)
207{
208 blkAddr = blk_addr;
209 blkSize = blk_size;
210 isSecure = target->isSecure();
211 readyTime = when_ready;
212 order = _order;
213 assert(target);
214 isForward = false;
215 allocOnFill = alloc_on_fill;
216 _isUncacheable = target->req->isUncacheable();
217 inService = false;
218 downstreamPending = false;
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, when_ready, _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
| 87 }
88
89 // StoreCondReq is effectively an upgrade if it's in an MSHR
90 // since it would have been failed already if we didn't have a
91 // read-only copy
92 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
93 hasUpgrade = true;
94 }
95 }
96
97 if (markPending) {
98 // Iterate over the SenderState stack and see if we find
99 // an MSHR entry. If we do, set the downstreamPending
100 // flag. Otherwise, do nothing.
101 MSHR *mshr = pkt->findNextSenderState<MSHR>();
102 if (mshr != NULL) {
103 assert(!mshr->downstreamPending);
104 mshr->downstreamPending = true;
105 } else {
106 // No need to clear downstreamPending later
107 markPending = false;
108 }
109 }
110
111 emplace_back(pkt, readyTime, order, source, markPending);
112}
113
114
115static void
116replaceUpgrade(PacketPtr pkt)
117{
118 if (pkt->cmd == MemCmd::UpgradeReq) {
119 pkt->cmd = MemCmd::ReadExReq;
120 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
121 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
122 pkt->cmd = MemCmd::SCUpgradeFailReq;
123 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
124 } else if (pkt->cmd == MemCmd::StoreCondReq) {
125 pkt->cmd = MemCmd::StoreCondFailReq;
126 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
127 }
128}
129
130
131void
132MSHR::TargetList::replaceUpgrades()
133{
134 if (!hasUpgrade)
135 return;
136
137 for (auto& t : *this) {
138 replaceUpgrade(t.pkt);
139 }
140
141 hasUpgrade = false;
142}
143
144
145void
146MSHR::TargetList::clearDownstreamPending()
147{
148 for (auto& t : *this) {
149 if (t.markedPending) {
150 // Iterate over the SenderState stack and see if we find
151 // an MSHR entry. If we find one, clear the
152 // downstreamPending flag by calling
153 // clearDownstreamPending(). This recursively clears the
154 // downstreamPending flag in all caches this packet has
155 // passed through.
156 MSHR *mshr = t.pkt->findNextSenderState<MSHR>();
157 if (mshr != NULL) {
158 mshr->clearDownstreamPending();
159 }
160 }
161 }
162}
163
164
165bool
166MSHR::TargetList::checkFunctional(PacketPtr pkt)
167{
168 for (auto& t : *this) {
169 if (pkt->checkFunctional(t.pkt)) {
170 return true;
171 }
172 }
173
174 return false;
175}
176
177
178void
179MSHR::TargetList::print(std::ostream &os, int verbosity,
180 const std::string &prefix) const
181{
182 for (auto& t : *this) {
183 const char *s;
184 switch (t.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 t.pkt->print(os, verbosity, "");
200 }
201}
202
203
204void
205MSHR::allocate(Addr blk_addr, unsigned blk_size, PacketPtr target,
206 Tick when_ready, Counter _order, bool alloc_on_fill)
207{
208 blkAddr = blk_addr;
209 blkSize = blk_size;
210 isSecure = target->isSecure();
211 readyTime = when_ready;
212 order = _order;
213 assert(target);
214 isForward = false;
215 allocOnFill = alloc_on_fill;
216 _isUncacheable = target->req->isUncacheable();
217 inService = false;
218 downstreamPending = false;
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, when_ready, _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
|
241MSHR::markInService(bool pending_dirty_resp)
| 241MSHR::markInService(bool pending_modified_resp)
|
242{
243 assert(!inService);
244 if (isForwardNoResponse()) {
245 // we just forwarded the request packet & don't expect a
246 // response, so get rid of it
247 assert(getNumTargets() == 1);
248 popTarget();
249 return true;
250 }
251
252 inService = true;
| 242{
243 assert(!inService);
244 if (isForwardNoResponse()) {
245 // we just forwarded the request packet & don't expect a
246 // response, so get rid of it
247 assert(getNumTargets() == 1);
248 popTarget();
249 return true;
250 }
251
252 inService = true;
|
253 pendingDirty = targets.needsExclusive || pending_dirty_resp;
| 253 pendingModified = targets.needsWritable || pending_modified_resp;
|
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 bool alloc_on_fill)
280{
281 // assume we'd never issue a prefetch when we've got an
282 // outstanding miss
283 assert(pkt->cmd != MemCmd::HardPFReq);
284
285 // uncacheable accesses always allocate a new MSHR, and cacheable
286 // accesses ignore any uncacheable MSHRs, thus we should never
287 // have targets addded if originally allocated uncacheable
288 assert(!_isUncacheable);
289
290 // potentially re-evaluate whether we should allocate on a fill or
291 // not
292 allocOnFill = allocOnFill || alloc_on_fill;
293
294 // if there's a request already in service for this MSHR, we will
295 // have to defer the new target until after the response if any of
296 // the following are true:
297 // - there are other targets already deferred
298 // - there's a pending invalidate to be applied after the response
299 // comes back (but before this target is processed)
| 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 bool alloc_on_fill)
280{
281 // assume we'd never issue a prefetch when we've got an
282 // outstanding miss
283 assert(pkt->cmd != MemCmd::HardPFReq);
284
285 // uncacheable accesses always allocate a new MSHR, and cacheable
286 // accesses ignore any uncacheable MSHRs, thus we should never
287 // have targets addded if originally allocated uncacheable
288 assert(!_isUncacheable);
289
290 // potentially re-evaluate whether we should allocate on a fill or
291 // not
292 allocOnFill = allocOnFill || alloc_on_fill;
293
294 // if there's a request already in service for this MSHR, we will
295 // have to defer the new target until after the response if any of
296 // the following are true:
297 // - there are other targets already deferred
298 // - there's a pending invalidate to be applied after the response
299 // comes back (but before this target is processed)
|
300 // - this target requires an exclusive block and either we're not
301 // getting an exclusive block back or we have already snooped
302 // another read request that will downgrade our exclusive block
303 // to shared
| 300 // - this target requires a writable block and either we're not
301 // getting a writable block back or we have already snooped
302 // another read request that will downgrade our writable block
303 // to non-writable (Shared or Owned)
|
304 if (inService &&
305 (!deferredTargets.empty() || hasPostInvalidate() ||
| 304 if (inService &&
305 (!deferredTargets.empty() || hasPostInvalidate() ||
|
306 (pkt->needsExclusive() &&
307 (!isPendingDirty() || hasPostDowngrade() || isForward)))) {
| 306 (pkt->needsWritable() &&
307 (!isPendingModified() || hasPostDowngrade() || isForward)))) {
|
308 // need to put on deferred list
309 if (hasPostInvalidate())
310 replaceUpgrade(pkt);
311 deferredTargets.add(pkt, whenReady, _order, Target::FromCPU, true);
312 } else {
313 // No request outstanding, or still OK to append to
314 // outstanding request: append to regular target list. Only
315 // mark pending if current request hasn't been issued yet
316 // (isn't in service).
317 targets.add(pkt, whenReady, _order, Target::FromCPU, !inService);
318 }
319}
320
321bool
322MSHR::handleSnoop(PacketPtr pkt, Counter _order)
323{
324 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
325 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
326
| 308 // need to put on deferred list
309 if (hasPostInvalidate())
310 replaceUpgrade(pkt);
311 deferredTargets.add(pkt, whenReady, _order, Target::FromCPU, true);
312 } else {
313 // No request outstanding, or still OK to append to
314 // outstanding request: append to regular target list. Only
315 // mark pending if current request hasn't been issued yet
316 // (isn't in service).
317 targets.add(pkt, whenReady, _order, Target::FromCPU, !inService);
318 }
319}
320
321bool
322MSHR::handleSnoop(PacketPtr pkt, Counter _order)
323{
324 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
325 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
326
|
327 // when we snoop packets the needsExclusive and isInvalidate flags
| 327 // when we snoop packets the needsWritable and isInvalidate flags
|
328 // should always be the same, however, this assumes that we never
329 // snoop writes as they are currently not marked as invalidations
| 328 // should always be the same, however, this assumes that we never
329 // snoop writes as they are currently not marked as invalidations
|
330 panic_if(pkt->needsExclusive() != pkt->isInvalidate(),
331 "%s got snoop %s to addr %#llx where needsExclusive, "
| 330 panic_if(pkt->needsWritable() != pkt->isInvalidate(),
331 "%s got snoop %s to addr %#llx where needsWritable, "
|
332 "does not match isInvalidate", name(), pkt->cmdString(),
333 pkt->getAddr());
334
335 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
336 // Request has not been issued yet, or it's been issued
337 // locally but is buffered unissued at some downstream cache
338 // which is forwarding us this snoop. Either way, the packet
339 // we're snooping logically precedes this MSHR's request, so
340 // the snoop has no impact on the MSHR, but must be processed
341 // in the standard way by the cache. The only exception is
342 // that if we're an L2+ cache buffering an UpgradeReq from a
343 // higher-level cache, and the snoop is invalidating, then our
344 // buffered upgrades must be converted to read exclusives,
345 // since the upper-level cache no longer has a valid copy.
346 // That is, even though the upper-level cache got out on its
347 // local bus first, some other invalidating transaction
348 // reached the global bus before the upgrade did.
| 332 "does not match isInvalidate", name(), pkt->cmdString(),
333 pkt->getAddr());
334
335 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
336 // Request has not been issued yet, or it's been issued
337 // locally but is buffered unissued at some downstream cache
338 // which is forwarding us this snoop. Either way, the packet
339 // we're snooping logically precedes this MSHR's request, so
340 // the snoop has no impact on the MSHR, but must be processed
341 // in the standard way by the cache. The only exception is
342 // that if we're an L2+ cache buffering an UpgradeReq from a
343 // higher-level cache, and the snoop is invalidating, then our
344 // buffered upgrades must be converted to read exclusives,
345 // since the upper-level cache no longer has a valid copy.
346 // That is, even though the upper-level cache got out on its
347 // local bus first, some other invalidating transaction
348 // reached the global bus before the upgrade did.
|
349 if (pkt->needsExclusive()) {
| 349 if (pkt->needsWritable()) {
|
350 targets.replaceUpgrades();
351 deferredTargets.replaceUpgrades();
352 }
353
354 return false;
355 }
356
357 // From here on down, the request issued by this MSHR logically
358 // precedes the request we're snooping.
| 350 targets.replaceUpgrades();
351 deferredTargets.replaceUpgrades();
352 }
353
354 return false;
355 }
356
357 // From here on down, the request issued by this MSHR logically
358 // precedes the request we're snooping.
|
359 if (pkt->needsExclusive()) {
| 359 if (pkt->needsWritable()) {
|
360 // snooped request still precedes the re-request we'll have to
361 // issue for deferred targets, if any...
362 deferredTargets.replaceUpgrades();
363 }
364
365 if (hasPostInvalidate()) {
366 // a prior snoop has already appended an invalidation, so
367 // logically we don't have the block anymore; no need for
368 // further snooping.
369 return true;
370 }
371
| 360 // snooped request still precedes the re-request we'll have to
361 // issue for deferred targets, if any...
362 deferredTargets.replaceUpgrades();
363 }
364
365 if (hasPostInvalidate()) {
366 // a prior snoop has already appended an invalidation, so
367 // logically we don't have the block anymore; no need for
368 // further snooping.
369 return true;
370 }
371
|
372 if (isPendingDirty() || pkt->isInvalidate()) {
| 372 if (isPendingModified() || pkt->isInvalidate()) {
|
373 // We need to save and replay the packet in two cases:
| 373 // We need to save and replay the packet in two cases:
|
374 // 1. We're awaiting an exclusive copy, so ownership is pending,
375 // and we need to deal with the snoop after we receive data.
| 374 // 1. We're awaiting a writable copy (Modified or Exclusive),
375 // so this MSHR is the orgering point, and we need to respond
376 // after we receive data.
|
376 // 2. It's an invalidation (e.g., UpgradeReq), and we need
377 // to forward the snoop up the hierarchy after the current
378 // transaction completes.
379
380 // Start by determining if we will eventually respond or not,
381 // matching the conditions checked in Cache::handleSnoop
| 377 // 2. It's an invalidation (e.g., UpgradeReq), and we need
378 // to forward the snoop up the hierarchy after the current
379 // transaction completes.
380
381 // Start by determining if we will eventually respond or not,
382 // matching the conditions checked in Cache::handleSnoop
|
382 bool will_respond = isPendingDirty() && pkt->needsResponse() &&
| 383 bool will_respond = isPendingModified() && pkt->needsResponse() &&
|
383 pkt->cmd != MemCmd::InvalidateReq;
384
385 // The packet we are snooping may be deleted by the time we
386 // actually process the target, and we consequently need to
387 // save a copy here. Clear flags and also allocate new data as
388 // the original packet data storage may have been deleted by
389 // the time we get to process this packet. In the cases where
390 // we are not responding after handling the snoop we also need
391 // to create a copy of the request to be on the safe side. In
392 // the latter case the cache is responsible for deleting both
393 // the packet and the request as part of handling the deferred
394 // snoop.
395 PacketPtr cp_pkt = will_respond ? new Packet(pkt, true, true) :
396 new Packet(new Request(*pkt->req), pkt->cmd);
397
| 384 pkt->cmd != MemCmd::InvalidateReq;
385
386 // The packet we are snooping may be deleted by the time we
387 // actually process the target, and we consequently need to
388 // save a copy here. Clear flags and also allocate new data as
389 // the original packet data storage may have been deleted by
390 // the time we get to process this packet. In the cases where
391 // we are not responding after handling the snoop we also need
392 // to create a copy of the request to be on the safe side. In
393 // the latter case the cache is responsible for deleting both
394 // the packet and the request as part of handling the deferred
395 // snoop.
396 PacketPtr cp_pkt = will_respond ? new Packet(pkt, true, true) :
397 new Packet(new Request(*pkt->req), pkt->cmd);
398
|
398 if (isPendingDirty()) {
399 // The new packet will need to get the response from the
400 // MSHR already queued up here
401 pkt->assertMemInhibit();
| 399 if (isPendingModified()) {
400 // we are the ordering point, and will consequently
401 // respond, and depending on whether the packet
402 // needsWritable or not we either pass a Shared line or a
403 // Modified line
404 pkt->setCacheResponding();
405
406 // inform the cache hierarchy that this cache had the line
407 // in the Modified state, even if the response is passed
408 // as Shared (and thus non-writable)
409 pkt->setResponderHadWritable();
410
|
402 // in the case of an uncacheable request there is no need
| 411 // in the case of an uncacheable request there is no need
|
403 // to set the exclusive flag, but since the recipient does
404 // not care there is no harm in doing so
405 pkt->setSupplyExclusive();
| 412 // to set the responderHadWritable flag, but since the
413 // recipient does not care there is no harm in doing so
|
406 }
407 targets.add(cp_pkt, curTick(), _order, Target::FromSnoop,
| 414 }
415 targets.add(cp_pkt, curTick(), _order, Target::FromSnoop,
|
408 downstreamPending && targets.needsExclusive);
| 416 downstreamPending && targets.needsWritable);
|
409
| 417
|
410 if (pkt->needsExclusive()) {
| 418 if (pkt->needsWritable()) {
|
411 // This transaction will take away our pending copy
412 postInvalidate = true;
413 }
414 }
415
| 419 // This transaction will take away our pending copy
420 postInvalidate = true;
421 }
422 }
423
|
416 if (!pkt->needsExclusive() && !pkt->req->isUncacheable()) {
| 424 if (!pkt->needsWritable() && !pkt->req->isUncacheable()) {
|
417 // This transaction will get a read-shared copy, downgrading
| 425 // This transaction will get a read-shared copy, downgrading
|
418 // our copy if we had an exclusive one
| 426 // our copy if we had a writable one
|
419 postDowngrade = true;
| 427 postDowngrade = true;
|
420 pkt->assertShared();
| 428 // make sure that any downstream cache does not respond with a
429 // writable (and dirty) copy even if it has one, unless it was
430 // explicitly asked for one
431 pkt->setHasSharers();
|
421 }
422
423 return true;
424}
425
426
427bool
428MSHR::promoteDeferredTargets()
429{
430 assert(targets.empty());
431 if (deferredTargets.empty()) {
432 return false;
433 }
434
435 // swap targets & deferredTargets lists
436 std::swap(targets, deferredTargets);
437
438 // clear deferredTargets flags
439 deferredTargets.resetFlags();
440
441 order = targets.front().order;
442 readyTime = std::max(curTick(), targets.front().readyTime);
443
444 return true;
445}
446
447
448void
| 432 }
433
434 return true;
435}
436
437
438bool
439MSHR::promoteDeferredTargets()
440{
441 assert(targets.empty());
442 if (deferredTargets.empty()) {
443 return false;
444 }
445
446 // swap targets & deferredTargets lists
447 std::swap(targets, deferredTargets);
448
449 // clear deferredTargets flags
450 deferredTargets.resetFlags();
451
452 order = targets.front().order;
453 readyTime = std::max(curTick(), targets.front().readyTime);
454
455 return true;
456}
457
458
459void
|
449MSHR::promoteExclusive()
| 460MSHR::promoteWritable()
|
450{
| 461{
|
451 if (deferredTargets.needsExclusive &&
| 462 if (deferredTargets.needsWritable &&
|
452 !(hasPostInvalidate() || hasPostDowngrade())) {
| 463 !(hasPostInvalidate() || hasPostDowngrade())) {
|
453 // We got an exclusive response, but we have deferred targets
454 // which are waiting to request an exclusive copy (not because
| 464 // We got a writable response, but we have deferred targets
465 // which are waiting to request a writable copy (not because
|
455 // of a pending invalidate). This can happen if the original
| 466 // of a pending invalidate). This can happen if the original
|
456 // request was for a read-only (non-exclusive) block, but we
457 // got an exclusive copy anyway because of the E part of the
458 // MOESI/MESI protocol. Since we got the exclusive copy
459 // there's no need to defer the targets, so move them up to
460 // the regular target list.
461 assert(!targets.needsExclusive);
462 targets.needsExclusive = true;
| 467 // request was for a read-only block, but we got a writable
468 // response anyway. Since we got the writable copy there's no
469 // need to defer the targets, so move them up to the regular
470 // target list.
471 assert(!targets.needsWritable);
472 targets.needsWritable = true;
|
463 // if any of the deferred targets were upper-level cache
464 // requests marked downstreamPending, need to clear that
465 assert(!downstreamPending); // not pending here anymore
466 deferredTargets.clearDownstreamPending();
467 // this clears out deferredTargets too
468 targets.splice(targets.end(), deferredTargets);
469 deferredTargets.resetFlags();
470 }
471}
472
473
474bool
475MSHR::checkFunctional(PacketPtr pkt)
476{
477 // For printing, we treat the MSHR as a whole as single entity.
478 // For other requests, we iterate over the individual targets
479 // since that's where the actual data lies.
480 if (pkt->isPrint()) {
481 pkt->checkFunctional(this, blkAddr, isSecure, blkSize, NULL);
482 return false;
483 } else {
484 return (targets.checkFunctional(pkt) ||
485 deferredTargets.checkFunctional(pkt));
486 }
487}
488
489
490void
491MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
492{
493 ccprintf(os, "%s[%#llx:%#llx](%s) %s %s %s state: %s %s %s %s %s\n",
494 prefix, blkAddr, blkAddr + blkSize - 1,
495 isSecure ? "s" : "ns",
496 isForward ? "Forward" : "",
497 allocOnFill ? "AllocOnFill" : "",
498 isForwardNoResponse() ? "ForwNoResp" : "",
| 473 // if any of the deferred targets were upper-level cache
474 // requests marked downstreamPending, need to clear that
475 assert(!downstreamPending); // not pending here anymore
476 deferredTargets.clearDownstreamPending();
477 // this clears out deferredTargets too
478 targets.splice(targets.end(), deferredTargets);
479 deferredTargets.resetFlags();
480 }
481}
482
483
484bool
485MSHR::checkFunctional(PacketPtr pkt)
486{
487 // For printing, we treat the MSHR as a whole as single entity.
488 // For other requests, we iterate over the individual targets
489 // since that's where the actual data lies.
490 if (pkt->isPrint()) {
491 pkt->checkFunctional(this, blkAddr, isSecure, blkSize, NULL);
492 return false;
493 } else {
494 return (targets.checkFunctional(pkt) ||
495 deferredTargets.checkFunctional(pkt));
496 }
497}
498
499
500void
501MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
502{
503 ccprintf(os, "%s[%#llx:%#llx](%s) %s %s %s state: %s %s %s %s %s\n",
504 prefix, blkAddr, blkAddr + blkSize - 1,
505 isSecure ? "s" : "ns",
506 isForward ? "Forward" : "",
507 allocOnFill ? "AllocOnFill" : "",
508 isForwardNoResponse() ? "ForwNoResp" : "",
|
499 needsExclusive() ? "Excl" : "",
| 509 needsWritable() ? "Wrtbl" : "",
|
500 _isUncacheable ? "Unc" : "",
501 inService ? "InSvc" : "",
502 downstreamPending ? "DwnPend" : "",
503 hasPostInvalidate() ? "PostInv" : "",
504 hasPostDowngrade() ? "PostDowngr" : "");
505
506 ccprintf(os, "%s Targets:\n", prefix);
507 targets.print(os, verbosity, prefix + " ");
508 if (!deferredTargets.empty()) {
509 ccprintf(os, "%s Deferred Targets:\n", prefix);
510 deferredTargets.print(os, verbosity, prefix + " ");
511 }
512}
513
514std::string
515MSHR::print() const
516{
517 ostringstream str;
518 print(str);
519 return str.str();
520}
| 510 _isUncacheable ? "Unc" : "",
511 inService ? "InSvc" : "",
512 downstreamPending ? "DwnPend" : "",
513 hasPostInvalidate() ? "PostInv" : "",
514 hasPostDowngrade() ? "PostDowngr" : "");
515
516 ccprintf(os, "%s Targets:\n", prefix);
517 targets.print(os, verbosity, prefix + " ");
518 if (!deferredTargets.empty()) {
519 ccprintf(os, "%s Deferred Targets:\n", prefix);
520 deferredTargets.print(os, verbosity, prefix + " ");
521 }
522}
523
524std::string
525MSHR::print() const
526{
527 ostringstream str;
528 print(str);
529 return str.str();
530}
|