1/*
| 1/*
|
2 * Copyright (c) 2012-2013, 2015 ARM Limited
| 2 * Copyright (c) 2012-2013, 2015-2016 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
| 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),
| 64MSHR::MSHR() : downstreamPending(false),
|
65 pendingModified(false),
66 postInvalidate(false), postDowngrade(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)
| 67 isForward(false), allocOnFill(false)
|
71{
72}
73
| 68{
69}
70
|
74
| |
75MSHR::TargetList::TargetList()
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) {
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 // remember if the current packet has data allocated
119 bool has_data = pkt->hasData() || pkt->hasRespData();
120
121 if (pkt->cmd == MemCmd::UpgradeReq) {
122 pkt->cmd = MemCmd::ReadExReq;
123 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
124 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
125 pkt->cmd = MemCmd::SCUpgradeFailReq;
126 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
127 } else if (pkt->cmd == MemCmd::StoreCondReq) {
128 pkt->cmd = MemCmd::StoreCondFailReq;
129 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
130 }
131
132 if (!has_data) {
133 // there is no sensible way of setting the data field if the
134 // new command actually would carry data
135 assert(!pkt->hasData());
136
137 if (pkt->hasRespData()) {
138 // we went from a packet that had no data (neither request,
139 // nor response), to one that does, and therefore we need to
140 // actually allocate space for the data payload
141 pkt->allocate();
142 }
143 }
144}
145
146
147void
148MSHR::TargetList::replaceUpgrades()
149{
150 if (!hasUpgrade)
151 return;
152
153 for (auto& t : *this) {
154 replaceUpgrade(t.pkt);
155 }
156
157 hasUpgrade = false;
158}
159
160
161void
162MSHR::TargetList::clearDownstreamPending()
163{
164 for (auto& t : *this) {
165 if (t.markedPending) {
166 // Iterate over the SenderState stack and see if we find
167 // an MSHR entry. If we find one, clear the
168 // downstreamPending flag by calling
169 // clearDownstreamPending(). This recursively clears the
170 // downstreamPending flag in all caches this packet has
171 // passed through.
172 MSHR *mshr = t.pkt->findNextSenderState<MSHR>();
173 if (mshr != NULL) {
174 mshr->clearDownstreamPending();
175 }
176 }
177 }
178}
179
180
181bool
182MSHR::TargetList::checkFunctional(PacketPtr pkt)
183{
184 for (auto& t : *this) {
185 if (pkt->checkFunctional(t.pkt)) {
186 return true;
187 }
188 }
189
190 return false;
191}
192
193
194void
195MSHR::TargetList::print(std::ostream &os, int verbosity,
196 const std::string &prefix) const
197{
198 for (auto& t : *this) {
199 const char *s;
200 switch (t.source) {
201 case Target::FromCPU:
202 s = "FromCPU";
203 break;
204 case Target::FromSnoop:
205 s = "FromSnoop";
206 break;
207 case Target::FromPrefetcher:
208 s = "FromPrefetcher";
209 break;
210 default:
211 s = "";
212 break;
213 }
214 ccprintf(os, "%s%s: ", prefix, s);
215 t.pkt->print(os, verbosity, "");
216 }
217}
218
219
220void
221MSHR::allocate(Addr blk_addr, unsigned blk_size, PacketPtr target,
222 Tick when_ready, Counter _order, bool alloc_on_fill)
223{
224 blkAddr = blk_addr;
225 blkSize = blk_size;
226 isSecure = target->isSecure();
227 readyTime = when_ready;
228 order = _order;
229 assert(target);
230 isForward = false;
231 allocOnFill = alloc_on_fill;
232 _isUncacheable = target->req->isUncacheable();
233 inService = false;
234 downstreamPending = false;
235 assert(targets.isReset());
236 // Don't know of a case where we would allocate a new MSHR for a
237 // snoop (mem-side request), so set source according to request here
238 Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
239 Target::FromPrefetcher : Target::FromCPU;
240 targets.add(target, when_ready, _order, source, true);
241 assert(deferredTargets.isReset());
| 71MSHR::TargetList::TargetList()
72 : needsWritable(false), hasUpgrade(false)
73{}
74
75
76inline void
77MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
78 Counter order, Target::Source source, bool markPending)
79{
80 if (source != Target::FromSnoop) {
81 if (pkt->needsWritable()) {
82 needsWritable = true;
83 }
84
85 // StoreCondReq is effectively an upgrade if it's in an MSHR
86 // since it would have been failed already if we didn't have a
87 // read-only copy
88 if (pkt->isUpgrade() || pkt->cmd == MemCmd::StoreCondReq) {
89 hasUpgrade = true;
90 }
91 }
92
93 if (markPending) {
94 // Iterate over the SenderState stack and see if we find
95 // an MSHR entry. If we do, set the downstreamPending
96 // flag. Otherwise, do nothing.
97 MSHR *mshr = pkt->findNextSenderState<MSHR>();
98 if (mshr != NULL) {
99 assert(!mshr->downstreamPending);
100 mshr->downstreamPending = true;
101 } else {
102 // No need to clear downstreamPending later
103 markPending = false;
104 }
105 }
106
107 emplace_back(pkt, readyTime, order, source, markPending);
108}
109
110
111static void
112replaceUpgrade(PacketPtr pkt)
113{
114 // remember if the current packet has data allocated
115 bool has_data = pkt->hasData() || pkt->hasRespData();
116
117 if (pkt->cmd == MemCmd::UpgradeReq) {
118 pkt->cmd = MemCmd::ReadExReq;
119 DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
120 } else if (pkt->cmd == MemCmd::SCUpgradeReq) {
121 pkt->cmd = MemCmd::SCUpgradeFailReq;
122 DPRINTF(Cache, "Replacing SCUpgradeReq with SCUpgradeFailReq\n");
123 } else if (pkt->cmd == MemCmd::StoreCondReq) {
124 pkt->cmd = MemCmd::StoreCondFailReq;
125 DPRINTF(Cache, "Replacing StoreCondReq with StoreCondFailReq\n");
126 }
127
128 if (!has_data) {
129 // there is no sensible way of setting the data field if the
130 // new command actually would carry data
131 assert(!pkt->hasData());
132
133 if (pkt->hasRespData()) {
134 // we went from a packet that had no data (neither request,
135 // nor response), to one that does, and therefore we need to
136 // actually allocate space for the data payload
137 pkt->allocate();
138 }
139 }
140}
141
142
143void
144MSHR::TargetList::replaceUpgrades()
145{
146 if (!hasUpgrade)
147 return;
148
149 for (auto& t : *this) {
150 replaceUpgrade(t.pkt);
151 }
152
153 hasUpgrade = false;
154}
155
156
157void
158MSHR::TargetList::clearDownstreamPending()
159{
160 for (auto& t : *this) {
161 if (t.markedPending) {
162 // Iterate over the SenderState stack and see if we find
163 // an MSHR entry. If we find one, clear the
164 // downstreamPending flag by calling
165 // clearDownstreamPending(). This recursively clears the
166 // downstreamPending flag in all caches this packet has
167 // passed through.
168 MSHR *mshr = t.pkt->findNextSenderState<MSHR>();
169 if (mshr != NULL) {
170 mshr->clearDownstreamPending();
171 }
172 }
173 }
174}
175
176
177bool
178MSHR::TargetList::checkFunctional(PacketPtr pkt)
179{
180 for (auto& t : *this) {
181 if (pkt->checkFunctional(t.pkt)) {
182 return true;
183 }
184 }
185
186 return false;
187}
188
189
190void
191MSHR::TargetList::print(std::ostream &os, int verbosity,
192 const std::string &prefix) const
193{
194 for (auto& t : *this) {
195 const char *s;
196 switch (t.source) {
197 case Target::FromCPU:
198 s = "FromCPU";
199 break;
200 case Target::FromSnoop:
201 s = "FromSnoop";
202 break;
203 case Target::FromPrefetcher:
204 s = "FromPrefetcher";
205 break;
206 default:
207 s = "";
208 break;
209 }
210 ccprintf(os, "%s%s: ", prefix, s);
211 t.pkt->print(os, verbosity, "");
212 }
213}
214
215
216void
217MSHR::allocate(Addr blk_addr, unsigned blk_size, PacketPtr target,
218 Tick when_ready, Counter _order, bool alloc_on_fill)
219{
220 blkAddr = blk_addr;
221 blkSize = blk_size;
222 isSecure = target->isSecure();
223 readyTime = when_ready;
224 order = _order;
225 assert(target);
226 isForward = false;
227 allocOnFill = alloc_on_fill;
228 _isUncacheable = target->req->isUncacheable();
229 inService = false;
230 downstreamPending = false;
231 assert(targets.isReset());
232 // Don't know of a case where we would allocate a new MSHR for a
233 // snoop (mem-side request), so set source according to request here
234 Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
235 Target::FromPrefetcher : Target::FromCPU;
236 targets.add(target, when_ready, _order, source, true);
237 assert(deferredTargets.isReset());
|
242 data = NULL;
| |
243}
244
245
246void
247MSHR::clearDownstreamPending()
248{
249 assert(downstreamPending);
250 downstreamPending = false;
251 // recursively clear flag on any MSHRs we will be forwarding
252 // responses to
253 targets.clearDownstreamPending();
254}
255
| 238}
239
240
241void
242MSHR::clearDownstreamPending()
243{
244 assert(downstreamPending);
245 downstreamPending = false;
246 // recursively clear flag on any MSHRs we will be forwarding
247 // responses to
248 targets.clearDownstreamPending();
249}
250
|
256bool
| 251void
|
257MSHR::markInService(bool pending_modified_resp)
258{
259 assert(!inService);
| 252MSHR::markInService(bool pending_modified_resp)
253{
254 assert(!inService);
|
260 if (isForwardNoResponse()) {
261 // we just forwarded the request packet & don't expect a
262 // response, so get rid of it
263 assert(getNumTargets() == 1);
264 popTarget();
265 return true;
266 }
| |
267
268 inService = true;
269 pendingModified = targets.needsWritable || pending_modified_resp;
270 postInvalidate = postDowngrade = false;
271
272 if (!downstreamPending) {
273 // let upstream caches know that the request has made it to a
274 // level where it's going to get a response
275 targets.clearDownstreamPending();
276 }
| 255
256 inService = true;
257 pendingModified = targets.needsWritable || pending_modified_resp;
258 postInvalidate = postDowngrade = false;
259
260 if (!downstreamPending) {
261 // let upstream caches know that the request has made it to a
262 // level where it's going to get a response
263 targets.clearDownstreamPending();
264 }
|
277 return false;
| |
278}
279
280
281void
282MSHR::deallocate()
283{
284 assert(targets.empty());
285 targets.resetFlags();
286 assert(deferredTargets.isReset());
287 inService = false;
288}
289
290/*
291 * Adds a target to an MSHR
292 */
293void
294MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order,
295 bool alloc_on_fill)
296{
297 // assume we'd never issue a prefetch when we've got an
298 // outstanding miss
299 assert(pkt->cmd != MemCmd::HardPFReq);
300
301 // uncacheable accesses always allocate a new MSHR, and cacheable
302 // accesses ignore any uncacheable MSHRs, thus we should never
303 // have targets addded if originally allocated uncacheable
304 assert(!_isUncacheable);
305
306 // potentially re-evaluate whether we should allocate on a fill or
307 // not
308 allocOnFill = allocOnFill || alloc_on_fill;
309
310 // if there's a request already in service for this MSHR, we will
311 // have to defer the new target until after the response if any of
312 // the following are true:
313 // - there are other targets already deferred
314 // - there's a pending invalidate to be applied after the response
315 // comes back (but before this target is processed)
316 // - this target requires a writable block and either we're not
317 // getting a writable block back or we have already snooped
318 // another read request that will downgrade our writable block
319 // to non-writable (Shared or Owned)
320 if (inService &&
321 (!deferredTargets.empty() || hasPostInvalidate() ||
322 (pkt->needsWritable() &&
323 (!isPendingModified() || hasPostDowngrade() || isForward)))) {
324 // need to put on deferred list
325 if (hasPostInvalidate())
326 replaceUpgrade(pkt);
327 deferredTargets.add(pkt, whenReady, _order, Target::FromCPU, true);
328 } else {
329 // No request outstanding, or still OK to append to
330 // outstanding request: append to regular target list. Only
331 // mark pending if current request hasn't been issued yet
332 // (isn't in service).
333 targets.add(pkt, whenReady, _order, Target::FromCPU, !inService);
334 }
335}
336
337bool
338MSHR::handleSnoop(PacketPtr pkt, Counter _order)
339{
340 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
341 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
342
343 // when we snoop packets the needsWritable and isInvalidate flags
344 // should always be the same, however, this assumes that we never
345 // snoop writes as they are currently not marked as invalidations
346 panic_if(pkt->needsWritable() != pkt->isInvalidate(),
347 "%s got snoop %s to addr %#llx where needsWritable, "
348 "does not match isInvalidate", name(), pkt->cmdString(),
349 pkt->getAddr());
350
351 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
352 // Request has not been issued yet, or it's been issued
353 // locally but is buffered unissued at some downstream cache
354 // which is forwarding us this snoop. Either way, the packet
355 // we're snooping logically precedes this MSHR's request, so
356 // the snoop has no impact on the MSHR, but must be processed
357 // in the standard way by the cache. The only exception is
358 // that if we're an L2+ cache buffering an UpgradeReq from a
359 // higher-level cache, and the snoop is invalidating, then our
360 // buffered upgrades must be converted to read exclusives,
361 // since the upper-level cache no longer has a valid copy.
362 // That is, even though the upper-level cache got out on its
363 // local bus first, some other invalidating transaction
364 // reached the global bus before the upgrade did.
365 if (pkt->needsWritable()) {
366 targets.replaceUpgrades();
367 deferredTargets.replaceUpgrades();
368 }
369
370 return false;
371 }
372
373 // From here on down, the request issued by this MSHR logically
374 // precedes the request we're snooping.
375 if (pkt->needsWritable()) {
376 // snooped request still precedes the re-request we'll have to
377 // issue for deferred targets, if any...
378 deferredTargets.replaceUpgrades();
379 }
380
381 if (hasPostInvalidate()) {
382 // a prior snoop has already appended an invalidation, so
383 // logically we don't have the block anymore; no need for
384 // further snooping.
385 return true;
386 }
387
388 if (isPendingModified() || pkt->isInvalidate()) {
389 // We need to save and replay the packet in two cases:
390 // 1. We're awaiting a writable copy (Modified or Exclusive),
391 // so this MSHR is the orgering point, and we need to respond
392 // after we receive data.
393 // 2. It's an invalidation (e.g., UpgradeReq), and we need
394 // to forward the snoop up the hierarchy after the current
395 // transaction completes.
396
397 // Start by determining if we will eventually respond or not,
398 // matching the conditions checked in Cache::handleSnoop
399 bool will_respond = isPendingModified() && pkt->needsResponse() &&
400 pkt->cmd != MemCmd::InvalidateReq;
401
402 // The packet we are snooping may be deleted by the time we
403 // actually process the target, and we consequently need to
404 // save a copy here. Clear flags and also allocate new data as
405 // the original packet data storage may have been deleted by
406 // the time we get to process this packet. In the cases where
407 // we are not responding after handling the snoop we also need
408 // to create a copy of the request to be on the safe side. In
409 // the latter case the cache is responsible for deleting both
410 // the packet and the request as part of handling the deferred
411 // snoop.
412 PacketPtr cp_pkt = will_respond ? new Packet(pkt, true, true) :
413 new Packet(new Request(*pkt->req), pkt->cmd);
414
415 if (isPendingModified()) {
416 // we are the ordering point, and will consequently
417 // respond, and depending on whether the packet
418 // needsWritable or not we either pass a Shared line or a
419 // Modified line
420 pkt->setCacheResponding();
421
422 // inform the cache hierarchy that this cache had the line
423 // in the Modified state, even if the response is passed
424 // as Shared (and thus non-writable)
425 pkt->setResponderHadWritable();
426
427 // in the case of an uncacheable request there is no need
428 // to set the responderHadWritable flag, but since the
429 // recipient does not care there is no harm in doing so
430 }
431 targets.add(cp_pkt, curTick(), _order, Target::FromSnoop,
432 downstreamPending && targets.needsWritable);
433
434 if (pkt->needsWritable()) {
435 // This transaction will take away our pending copy
436 postInvalidate = true;
437 }
438 }
439
440 if (!pkt->needsWritable() && !pkt->req->isUncacheable()) {
441 // This transaction will get a read-shared copy, downgrading
442 // our copy if we had a writable one
443 postDowngrade = true;
444 // make sure that any downstream cache does not respond with a
445 // writable (and dirty) copy even if it has one, unless it was
446 // explicitly asked for one
447 pkt->setHasSharers();
448 }
449
450 return true;
451}
452
453
454bool
455MSHR::promoteDeferredTargets()
456{
457 assert(targets.empty());
458 if (deferredTargets.empty()) {
459 return false;
460 }
461
462 // swap targets & deferredTargets lists
463 std::swap(targets, deferredTargets);
464
465 // clear deferredTargets flags
466 deferredTargets.resetFlags();
467
468 order = targets.front().order;
469 readyTime = std::max(curTick(), targets.front().readyTime);
470
471 return true;
472}
473
474
475void
476MSHR::promoteWritable()
477{
478 if (deferredTargets.needsWritable &&
479 !(hasPostInvalidate() || hasPostDowngrade())) {
480 // We got a writable response, but we have deferred targets
481 // which are waiting to request a writable copy (not because
482 // of a pending invalidate). This can happen if the original
483 // request was for a read-only block, but we got a writable
484 // response anyway. Since we got the writable copy there's no
485 // need to defer the targets, so move them up to the regular
486 // target list.
487 assert(!targets.needsWritable);
488 targets.needsWritable = true;
489 // if any of the deferred targets were upper-level cache
490 // requests marked downstreamPending, need to clear that
491 assert(!downstreamPending); // not pending here anymore
492 deferredTargets.clearDownstreamPending();
493 // this clears out deferredTargets too
494 targets.splice(targets.end(), deferredTargets);
495 deferredTargets.resetFlags();
496 }
497}
498
499
500bool
501MSHR::checkFunctional(PacketPtr pkt)
502{
503 // For printing, we treat the MSHR as a whole as single entity.
504 // For other requests, we iterate over the individual targets
505 // since that's where the actual data lies.
506 if (pkt->isPrint()) {
507 pkt->checkFunctional(this, blkAddr, isSecure, blkSize, NULL);
508 return false;
509 } else {
510 return (targets.checkFunctional(pkt) ||
511 deferredTargets.checkFunctional(pkt));
512 }
513}
514
| 265}
266
267
268void
269MSHR::deallocate()
270{
271 assert(targets.empty());
272 targets.resetFlags();
273 assert(deferredTargets.isReset());
274 inService = false;
275}
276
277/*
278 * Adds a target to an MSHR
279 */
280void
281MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order,
282 bool alloc_on_fill)
283{
284 // assume we'd never issue a prefetch when we've got an
285 // outstanding miss
286 assert(pkt->cmd != MemCmd::HardPFReq);
287
288 // uncacheable accesses always allocate a new MSHR, and cacheable
289 // accesses ignore any uncacheable MSHRs, thus we should never
290 // have targets addded if originally allocated uncacheable
291 assert(!_isUncacheable);
292
293 // potentially re-evaluate whether we should allocate on a fill or
294 // not
295 allocOnFill = allocOnFill || alloc_on_fill;
296
297 // if there's a request already in service for this MSHR, we will
298 // have to defer the new target until after the response if any of
299 // the following are true:
300 // - there are other targets already deferred
301 // - there's a pending invalidate to be applied after the response
302 // comes back (but before this target is processed)
303 // - this target requires a writable block and either we're not
304 // getting a writable block back or we have already snooped
305 // another read request that will downgrade our writable block
306 // to non-writable (Shared or Owned)
307 if (inService &&
308 (!deferredTargets.empty() || hasPostInvalidate() ||
309 (pkt->needsWritable() &&
310 (!isPendingModified() || hasPostDowngrade() || isForward)))) {
311 // need to put on deferred list
312 if (hasPostInvalidate())
313 replaceUpgrade(pkt);
314 deferredTargets.add(pkt, whenReady, _order, Target::FromCPU, true);
315 } else {
316 // No request outstanding, or still OK to append to
317 // outstanding request: append to regular target list. Only
318 // mark pending if current request hasn't been issued yet
319 // (isn't in service).
320 targets.add(pkt, whenReady, _order, Target::FromCPU, !inService);
321 }
322}
323
324bool
325MSHR::handleSnoop(PacketPtr pkt, Counter _order)
326{
327 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
328 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
329
330 // when we snoop packets the needsWritable and isInvalidate flags
331 // should always be the same, however, this assumes that we never
332 // snoop writes as they are currently not marked as invalidations
333 panic_if(pkt->needsWritable() != pkt->isInvalidate(),
334 "%s got snoop %s to addr %#llx where needsWritable, "
335 "does not match isInvalidate", name(), pkt->cmdString(),
336 pkt->getAddr());
337
338 if (!inService || (pkt->isExpressSnoop() && downstreamPending)) {
339 // Request has not been issued yet, or it's been issued
340 // locally but is buffered unissued at some downstream cache
341 // which is forwarding us this snoop. Either way, the packet
342 // we're snooping logically precedes this MSHR's request, so
343 // the snoop has no impact on the MSHR, but must be processed
344 // in the standard way by the cache. The only exception is
345 // that if we're an L2+ cache buffering an UpgradeReq from a
346 // higher-level cache, and the snoop is invalidating, then our
347 // buffered upgrades must be converted to read exclusives,
348 // since the upper-level cache no longer has a valid copy.
349 // That is, even though the upper-level cache got out on its
350 // local bus first, some other invalidating transaction
351 // reached the global bus before the upgrade did.
352 if (pkt->needsWritable()) {
353 targets.replaceUpgrades();
354 deferredTargets.replaceUpgrades();
355 }
356
357 return false;
358 }
359
360 // From here on down, the request issued by this MSHR logically
361 // precedes the request we're snooping.
362 if (pkt->needsWritable()) {
363 // snooped request still precedes the re-request we'll have to
364 // issue for deferred targets, if any...
365 deferredTargets.replaceUpgrades();
366 }
367
368 if (hasPostInvalidate()) {
369 // a prior snoop has already appended an invalidation, so
370 // logically we don't have the block anymore; no need for
371 // further snooping.
372 return true;
373 }
374
375 if (isPendingModified() || pkt->isInvalidate()) {
376 // We need to save and replay the packet in two cases:
377 // 1. We're awaiting a writable copy (Modified or Exclusive),
378 // so this MSHR is the orgering point, and we need to respond
379 // after we receive data.
380 // 2. It's an invalidation (e.g., UpgradeReq), and we need
381 // to forward the snoop up the hierarchy after the current
382 // transaction completes.
383
384 // Start by determining if we will eventually respond or not,
385 // matching the conditions checked in Cache::handleSnoop
386 bool will_respond = isPendingModified() && pkt->needsResponse() &&
387 pkt->cmd != MemCmd::InvalidateReq;
388
389 // The packet we are snooping may be deleted by the time we
390 // actually process the target, and we consequently need to
391 // save a copy here. Clear flags and also allocate new data as
392 // the original packet data storage may have been deleted by
393 // the time we get to process this packet. In the cases where
394 // we are not responding after handling the snoop we also need
395 // to create a copy of the request to be on the safe side. In
396 // the latter case the cache is responsible for deleting both
397 // the packet and the request as part of handling the deferred
398 // snoop.
399 PacketPtr cp_pkt = will_respond ? new Packet(pkt, true, true) :
400 new Packet(new Request(*pkt->req), pkt->cmd);
401
402 if (isPendingModified()) {
403 // we are the ordering point, and will consequently
404 // respond, and depending on whether the packet
405 // needsWritable or not we either pass a Shared line or a
406 // Modified line
407 pkt->setCacheResponding();
408
409 // inform the cache hierarchy that this cache had the line
410 // in the Modified state, even if the response is passed
411 // as Shared (and thus non-writable)
412 pkt->setResponderHadWritable();
413
414 // in the case of an uncacheable request there is no need
415 // to set the responderHadWritable flag, but since the
416 // recipient does not care there is no harm in doing so
417 }
418 targets.add(cp_pkt, curTick(), _order, Target::FromSnoop,
419 downstreamPending && targets.needsWritable);
420
421 if (pkt->needsWritable()) {
422 // This transaction will take away our pending copy
423 postInvalidate = true;
424 }
425 }
426
427 if (!pkt->needsWritable() && !pkt->req->isUncacheable()) {
428 // This transaction will get a read-shared copy, downgrading
429 // our copy if we had a writable one
430 postDowngrade = true;
431 // make sure that any downstream cache does not respond with a
432 // writable (and dirty) copy even if it has one, unless it was
433 // explicitly asked for one
434 pkt->setHasSharers();
435 }
436
437 return true;
438}
439
440
441bool
442MSHR::promoteDeferredTargets()
443{
444 assert(targets.empty());
445 if (deferredTargets.empty()) {
446 return false;
447 }
448
449 // swap targets & deferredTargets lists
450 std::swap(targets, deferredTargets);
451
452 // clear deferredTargets flags
453 deferredTargets.resetFlags();
454
455 order = targets.front().order;
456 readyTime = std::max(curTick(), targets.front().readyTime);
457
458 return true;
459}
460
461
462void
463MSHR::promoteWritable()
464{
465 if (deferredTargets.needsWritable &&
466 !(hasPostInvalidate() || hasPostDowngrade())) {
467 // We got a writable response, but we have deferred targets
468 // which are waiting to request a writable copy (not because
469 // of a pending invalidate). This can happen if the original
470 // request was for a read-only block, but we got a writable
471 // response anyway. Since we got the writable copy there's no
472 // need to defer the targets, so move them up to the regular
473 // target list.
474 assert(!targets.needsWritable);
475 targets.needsWritable = true;
476 // if any of the deferred targets were upper-level cache
477 // requests marked downstreamPending, need to clear that
478 assert(!downstreamPending); // not pending here anymore
479 deferredTargets.clearDownstreamPending();
480 // this clears out deferredTargets too
481 targets.splice(targets.end(), deferredTargets);
482 deferredTargets.resetFlags();
483 }
484}
485
486
487bool
488MSHR::checkFunctional(PacketPtr pkt)
489{
490 // For printing, we treat the MSHR as a whole as single entity.
491 // For other requests, we iterate over the individual targets
492 // since that's where the actual data lies.
493 if (pkt->isPrint()) {
494 pkt->checkFunctional(this, blkAddr, isSecure, blkSize, NULL);
495 return false;
496 } else {
497 return (targets.checkFunctional(pkt) ||
498 deferredTargets.checkFunctional(pkt));
499 }
500}
501
|
| 502bool
503MSHR::sendPacket(Cache &cache)
504{
505 return cache.sendMSHRQueuePacket(this);
506}
|
515
516void
517MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
518{
519 ccprintf(os, "%s[%#llx:%#llx](%s) %s %s %s state: %s %s %s %s %s\n",
520 prefix, blkAddr, blkAddr + blkSize - 1,
521 isSecure ? "s" : "ns",
522 isForward ? "Forward" : "",
523 allocOnFill ? "AllocOnFill" : "",
| 507
508void
509MSHR::print(std::ostream &os, int verbosity, const std::string &prefix) const
510{
511 ccprintf(os, "%s[%#llx:%#llx](%s) %s %s %s state: %s %s %s %s %s\n",
512 prefix, blkAddr, blkAddr + blkSize - 1,
513 isSecure ? "s" : "ns",
514 isForward ? "Forward" : "",
515 allocOnFill ? "AllocOnFill" : "",
|
524 isForwardNoResponse() ? "ForwNoResp" : "",
| |
525 needsWritable() ? "Wrtbl" : "",
526 _isUncacheable ? "Unc" : "",
527 inService ? "InSvc" : "",
528 downstreamPending ? "DwnPend" : "",
529 hasPostInvalidate() ? "PostInv" : "",
530 hasPostDowngrade() ? "PostDowngr" : "");
531
532 ccprintf(os, "%s Targets:\n", prefix);
533 targets.print(os, verbosity, prefix + " ");
534 if (!deferredTargets.empty()) {
535 ccprintf(os, "%s Deferred Targets:\n", prefix);
536 deferredTargets.print(os, verbosity, prefix + " ");
537 }
538}
539
540std::string
541MSHR::print() const
542{
543 ostringstream str;
544 print(str);
545 return str.str();
546}
| 516 needsWritable() ? "Wrtbl" : "",
517 _isUncacheable ? "Unc" : "",
518 inService ? "InSvc" : "",
519 downstreamPending ? "DwnPend" : "",
520 hasPostInvalidate() ? "PostInv" : "",
521 hasPostDowngrade() ? "PostDowngr" : "");
522
523 ccprintf(os, "%s Targets:\n", prefix);
524 targets.print(os, verbosity, prefix + " ");
525 if (!deferredTargets.empty()) {
526 ccprintf(os, "%s Deferred Targets:\n", prefix);
527 deferredTargets.print(os, verbosity, prefix + " ");
528 }
529}
530
531std::string
532MSHR::print() const
533{
534 ostringstream str;
535 print(str);
536 return str.str();
537}
|