1/*
2 * Copyright (c) 2014-2015 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 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions are
16 * met: redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer;
18 * redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution;
21 * neither the name of the copyright holders nor the names of its
22 * contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Authors: Mitch Hayenga
38 */
39
40#include "mem/cache/prefetch/queued.hh"
41
42#include <cassert>
43
44#include "base/logging.hh"
45#include "base/trace.hh"
46#include "debug/HWPrefetch.hh"
47#include "mem/request.hh"
48#include "params/QueuedPrefetcher.hh"
49
50QueuedPrefetcher::QueuedPrefetcher(const QueuedPrefetcherParams *p)
51 : BasePrefetcher(p), queueSize(p->queue_size), latency(p->latency),
52 queueSquash(p->queue_squash), queueFilter(p->queue_filter),
53 cacheSnoop(p->cache_snoop), tagPrefetch(p->tag_prefetch)
54{
55
56}
57
58QueuedPrefetcher::~QueuedPrefetcher()
59{
60 // Delete the queued prefetch packets
61 for (DeferredPacket &p : pfq) {
62 delete p.pkt;
63 }
64}
65
66void
67QueuedPrefetcher::notify(const PacketPtr &pkt, const PrefetchInfo &pfi)
68{
69 Addr blk_addr = blockAddress(pfi.getAddr());
70 bool is_secure = pfi.isSecure();
71
72 // Squash queued prefetches if demand miss to same line
73 if (queueSquash) {
74 auto itr = pfq.begin();
75 while (itr != pfq.end()) {
76 if (itr->pfInfo.getAddr() == blk_addr &&
77 itr->pfInfo.isSecure() == is_secure) {
78 delete itr->pkt;
79 itr = pfq.erase(itr);
80 } else {
81 ++itr;
82 }
83 }
84 }
85
86 // Calculate prefetches given this access
87 std::vector<AddrPriority> addresses;
88 calculatePrefetch(pfi, addresses);
89
90 // Queue up generated prefetches
91 for (AddrPriority& addr_prio : addresses) {
92
93 // Block align prefetch address
94 addr_prio.first = blockAddress(addr_prio.first);
95
96 if (samePage(pfi.getAddr(), addr_prio.first)) {
97 PrefetchInfo new_pfi(pfi,addr_prio.first);
98
99 pfIdentified++;
100 DPRINTF(HWPrefetch, "Found a pf candidate addr: %#x, "
101 "inserting into prefetch queue.\n", new_pfi.getAddr());
102
103 // Create and insert the request
104 insert(pkt, new_pfi, addr_prio.second);
105 } else {
106 // Record the number of page crossing prefetches generate
107 pfSpanPage += 1;
108 DPRINTF(HWPrefetch, "Ignoring page crossing prefetch.\n");
109 }
110 }
111}
112
113PacketPtr
114QueuedPrefetcher::getPacket()
115{
116 DPRINTF(HWPrefetch, "Requesting a prefetch to issue.\n");
117
118 if (pfq.empty()) {
119 DPRINTF(HWPrefetch, "No hardware prefetches available.\n");
120 return nullptr;
121 }
122
123 PacketPtr pkt = pfq.front().pkt;
124 pfq.pop_front();
125
126 pfIssued++;
| 1/*
2 * Copyright (c) 2014-2015 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 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions are
16 * met: redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer;
18 * redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution;
21 * neither the name of the copyright holders nor the names of its
22 * contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Authors: Mitch Hayenga
38 */
39
40#include "mem/cache/prefetch/queued.hh"
41
42#include <cassert>
43
44#include "base/logging.hh"
45#include "base/trace.hh"
46#include "debug/HWPrefetch.hh"
47#include "mem/request.hh"
48#include "params/QueuedPrefetcher.hh"
49
50QueuedPrefetcher::QueuedPrefetcher(const QueuedPrefetcherParams *p)
51 : BasePrefetcher(p), queueSize(p->queue_size), latency(p->latency),
52 queueSquash(p->queue_squash), queueFilter(p->queue_filter),
53 cacheSnoop(p->cache_snoop), tagPrefetch(p->tag_prefetch)
54{
55
56}
57
58QueuedPrefetcher::~QueuedPrefetcher()
59{
60 // Delete the queued prefetch packets
61 for (DeferredPacket &p : pfq) {
62 delete p.pkt;
63 }
64}
65
66void
67QueuedPrefetcher::notify(const PacketPtr &pkt, const PrefetchInfo &pfi)
68{
69 Addr blk_addr = blockAddress(pfi.getAddr());
70 bool is_secure = pfi.isSecure();
71
72 // Squash queued prefetches if demand miss to same line
73 if (queueSquash) {
74 auto itr = pfq.begin();
75 while (itr != pfq.end()) {
76 if (itr->pfInfo.getAddr() == blk_addr &&
77 itr->pfInfo.isSecure() == is_secure) {
78 delete itr->pkt;
79 itr = pfq.erase(itr);
80 } else {
81 ++itr;
82 }
83 }
84 }
85
86 // Calculate prefetches given this access
87 std::vector<AddrPriority> addresses;
88 calculatePrefetch(pfi, addresses);
89
90 // Queue up generated prefetches
91 for (AddrPriority& addr_prio : addresses) {
92
93 // Block align prefetch address
94 addr_prio.first = blockAddress(addr_prio.first);
95
96 if (samePage(pfi.getAddr(), addr_prio.first)) {
97 PrefetchInfo new_pfi(pfi,addr_prio.first);
98
99 pfIdentified++;
100 DPRINTF(HWPrefetch, "Found a pf candidate addr: %#x, "
101 "inserting into prefetch queue.\n", new_pfi.getAddr());
102
103 // Create and insert the request
104 insert(pkt, new_pfi, addr_prio.second);
105 } else {
106 // Record the number of page crossing prefetches generate
107 pfSpanPage += 1;
108 DPRINTF(HWPrefetch, "Ignoring page crossing prefetch.\n");
109 }
110 }
111}
112
113PacketPtr
114QueuedPrefetcher::getPacket()
115{
116 DPRINTF(HWPrefetch, "Requesting a prefetch to issue.\n");
117
118 if (pfq.empty()) {
119 DPRINTF(HWPrefetch, "No hardware prefetches available.\n");
120 return nullptr;
121 }
122
123 PacketPtr pkt = pfq.front().pkt;
124 pfq.pop_front();
125
126 pfIssued++;
|
127 assert(pkt != nullptr);
128 DPRINTF(HWPrefetch, "Generating prefetch for %#x.\n", pkt->getAddr());
129 return pkt;
130}
131
132QueuedPrefetcher::const_iterator
133QueuedPrefetcher::inPrefetch(const PrefetchInfo &pfi) const
134{
135 for (const_iterator dp = pfq.begin(); dp != pfq.end(); dp++) {
136 if (dp->pfInfo.sameAddr(pfi)) return dp;
137 }
138
139 return pfq.end();
140}
141
142QueuedPrefetcher::iterator
143QueuedPrefetcher::inPrefetch(const PrefetchInfo &pfi)
144{
145 for (iterator dp = pfq.begin(); dp != pfq.end(); dp++) {
146 if (dp->pfInfo.sameAddr(pfi)) return dp;
147 }
148
149 return pfq.end();
150}
151
152void
153QueuedPrefetcher::regStats()
154{
155 BasePrefetcher::regStats();
156
157 pfIdentified
158 .name(name() + ".pfIdentified")
159 .desc("number of prefetch candidates identified");
160
161 pfBufferHit
162 .name(name() + ".pfBufferHit")
163 .desc("number of redundant prefetches already in prefetch queue");
164
165 pfInCache
166 .name(name() + ".pfInCache")
167 .desc("number of redundant prefetches already in cache/mshr dropped");
168
169 pfRemovedFull
170 .name(name() + ".pfRemovedFull")
171 .desc("number of prefetches dropped due to prefetch queue size");
172
173 pfSpanPage
174 .name(name() + ".pfSpanPage")
175 .desc("number of prefetches not generated due to page crossing");
176}
177
178void
179QueuedPrefetcher::insert(const PacketPtr &pkt, PrefetchInfo &new_pfi,
180 int32_t priority)
181{
182 if (queueFilter) {
183 iterator it = inPrefetch(new_pfi);
184 /* If the address is already in the queue, update priority and leave */
185 if (it != pfq.end()) {
186 pfBufferHit++;
187 if (it->priority < priority) {
188 /* Update priority value and position in the queue */
189 it->priority = priority;
190 iterator prev = it;
191 bool cont = true;
192 while (cont && prev != pfq.begin()) {
193 prev--;
194 /* If the packet has higher priority, swap */
195 if (*it > *prev) {
196 std::swap(*it, *prev);
197 it = prev;
198 }
199 }
200 DPRINTF(HWPrefetch, "Prefetch addr already in "
201 "prefetch queue, priority updated\n");
202 } else {
203 DPRINTF(HWPrefetch, "Prefetch addr already in "
204 "prefetch queue\n");
205 }
206 return;
207 }
208 }
209
210 Addr target_addr = new_pfi.getAddr();
211 if (useVirtualAddresses) {
212 assert(pkt->req->hasPaddr());
213 //if we trained with virtual addresses, compute the phsysical address
214 if (new_pfi.getAddr() >= pkt->req->getVaddr()) {
215 //positive stride
216 target_addr = pkt->req->getPaddr() +
217 (new_pfi.getAddr() - pkt->req->getVaddr());
218 } else {
219 //negative stride
220 target_addr = pkt->req->getPaddr() -
221 (pkt->req->getVaddr() - new_pfi.getAddr());
222 }
223 }
224
225 if (cacheSnoop && (inCache(target_addr, new_pfi.isSecure()) ||
226 inMissQueue(target_addr, new_pfi.isSecure()))) {
227 pfInCache++;
228 DPRINTF(HWPrefetch, "Dropping redundant in "
229 "cache/MSHR prefetch addr:%#x\n", target_addr);
230 return;
231 }
232
233 /* Create a prefetch memory request */
234 RequestPtr pf_req =
235 std::make_shared<Request>(target_addr, blkSize, 0, masterId);
236
237 if (new_pfi.isSecure()) {
238 pf_req->setFlags(Request::SECURE);
239 }
240 pf_req->taskId(ContextSwitchTaskId::Prefetcher);
241 PacketPtr pf_pkt = new Packet(pf_req, MemCmd::HardPFReq);
242 pf_pkt->allocate();
243 if (tagPrefetch && new_pfi.hasPC()) {
244 // Tag prefetch packet with accessing pc
245 pf_pkt->req->setPC(new_pfi.getPC());
246 }
247
248 /* Verify prefetch buffer space for request */
249 if (pfq.size() == queueSize) {
250 pfRemovedFull++;
251 /* Lowest priority packet */
252 iterator it = pfq.end();
253 panic_if (it == pfq.begin(), "Prefetch queue is both full and empty!");
254 --it;
255 /* Look for oldest in that level of priority */
256 panic_if (it == pfq.begin(), "Prefetch queue is full with 1 element!");
257 iterator prev = it;
258 bool cont = true;
259 /* While not at the head of the queue */
260 while (cont && prev != pfq.begin()) {
261 prev--;
262 /* While at the same level of priority */
263 cont = prev->priority == it->priority;
264 if (cont)
265 /* update pointer */
266 it = prev;
267 }
268 DPRINTF(HWPrefetch, "Prefetch queue full, removing lowest priority "
269 "oldest packet, addr: %#x", it->pfInfo.getAddr());
270 delete it->pkt;
271 pfq.erase(it);
272 }
273
274 Tick pf_time = curTick() + clockPeriod() * latency;
275 DPRINTF(HWPrefetch, "Prefetch queued. "
276 "addr:%#x priority: %3d tick:%lld.\n",
277 target_addr, priority, pf_time);
278
279 /* Create the packet and find the spot to insert it */
280 DeferredPacket dpp(new_pfi, pf_time, pf_pkt, priority);
281 if (pfq.size() == 0) {
282 pfq.emplace_back(dpp);
283 } else {
284 iterator it = pfq.end();
285 do {
286 --it;
287 } while (it != pfq.begin() && dpp > *it);
288 /* If we reach the head, we have to see if the new element is new head
289 * or not */
290 if (it == pfq.begin() && dpp <= *it)
291 it++;
292 pfq.insert(it, dpp);
293 }
294}
| 128 assert(pkt != nullptr);
129 DPRINTF(HWPrefetch, "Generating prefetch for %#x.\n", pkt->getAddr());
130 return pkt;
131}
132
133QueuedPrefetcher::const_iterator
134QueuedPrefetcher::inPrefetch(const PrefetchInfo &pfi) const
135{
136 for (const_iterator dp = pfq.begin(); dp != pfq.end(); dp++) {
137 if (dp->pfInfo.sameAddr(pfi)) return dp;
138 }
139
140 return pfq.end();
141}
142
143QueuedPrefetcher::iterator
144QueuedPrefetcher::inPrefetch(const PrefetchInfo &pfi)
145{
146 for (iterator dp = pfq.begin(); dp != pfq.end(); dp++) {
147 if (dp->pfInfo.sameAddr(pfi)) return dp;
148 }
149
150 return pfq.end();
151}
152
153void
154QueuedPrefetcher::regStats()
155{
156 BasePrefetcher::regStats();
157
158 pfIdentified
159 .name(name() + ".pfIdentified")
160 .desc("number of prefetch candidates identified");
161
162 pfBufferHit
163 .name(name() + ".pfBufferHit")
164 .desc("number of redundant prefetches already in prefetch queue");
165
166 pfInCache
167 .name(name() + ".pfInCache")
168 .desc("number of redundant prefetches already in cache/mshr dropped");
169
170 pfRemovedFull
171 .name(name() + ".pfRemovedFull")
172 .desc("number of prefetches dropped due to prefetch queue size");
173
174 pfSpanPage
175 .name(name() + ".pfSpanPage")
176 .desc("number of prefetches not generated due to page crossing");
177}
178
179void
180QueuedPrefetcher::insert(const PacketPtr &pkt, PrefetchInfo &new_pfi,
181 int32_t priority)
182{
183 if (queueFilter) {
184 iterator it = inPrefetch(new_pfi);
185 /* If the address is already in the queue, update priority and leave */
186 if (it != pfq.end()) {
187 pfBufferHit++;
188 if (it->priority < priority) {
189 /* Update priority value and position in the queue */
190 it->priority = priority;
191 iterator prev = it;
192 bool cont = true;
193 while (cont && prev != pfq.begin()) {
194 prev--;
195 /* If the packet has higher priority, swap */
196 if (*it > *prev) {
197 std::swap(*it, *prev);
198 it = prev;
199 }
200 }
201 DPRINTF(HWPrefetch, "Prefetch addr already in "
202 "prefetch queue, priority updated\n");
203 } else {
204 DPRINTF(HWPrefetch, "Prefetch addr already in "
205 "prefetch queue\n");
206 }
207 return;
208 }
209 }
210
211 Addr target_addr = new_pfi.getAddr();
212 if (useVirtualAddresses) {
213 assert(pkt->req->hasPaddr());
214 //if we trained with virtual addresses, compute the phsysical address
215 if (new_pfi.getAddr() >= pkt->req->getVaddr()) {
216 //positive stride
217 target_addr = pkt->req->getPaddr() +
218 (new_pfi.getAddr() - pkt->req->getVaddr());
219 } else {
220 //negative stride
221 target_addr = pkt->req->getPaddr() -
222 (pkt->req->getVaddr() - new_pfi.getAddr());
223 }
224 }
225
226 if (cacheSnoop && (inCache(target_addr, new_pfi.isSecure()) ||
227 inMissQueue(target_addr, new_pfi.isSecure()))) {
228 pfInCache++;
229 DPRINTF(HWPrefetch, "Dropping redundant in "
230 "cache/MSHR prefetch addr:%#x\n", target_addr);
231 return;
232 }
233
234 /* Create a prefetch memory request */
235 RequestPtr pf_req =
236 std::make_shared<Request>(target_addr, blkSize, 0, masterId);
237
238 if (new_pfi.isSecure()) {
239 pf_req->setFlags(Request::SECURE);
240 }
241 pf_req->taskId(ContextSwitchTaskId::Prefetcher);
242 PacketPtr pf_pkt = new Packet(pf_req, MemCmd::HardPFReq);
243 pf_pkt->allocate();
244 if (tagPrefetch && new_pfi.hasPC()) {
245 // Tag prefetch packet with accessing pc
246 pf_pkt->req->setPC(new_pfi.getPC());
247 }
248
249 /* Verify prefetch buffer space for request */
250 if (pfq.size() == queueSize) {
251 pfRemovedFull++;
252 /* Lowest priority packet */
253 iterator it = pfq.end();
254 panic_if (it == pfq.begin(), "Prefetch queue is both full and empty!");
255 --it;
256 /* Look for oldest in that level of priority */
257 panic_if (it == pfq.begin(), "Prefetch queue is full with 1 element!");
258 iterator prev = it;
259 bool cont = true;
260 /* While not at the head of the queue */
261 while (cont && prev != pfq.begin()) {
262 prev--;
263 /* While at the same level of priority */
264 cont = prev->priority == it->priority;
265 if (cont)
266 /* update pointer */
267 it = prev;
268 }
269 DPRINTF(HWPrefetch, "Prefetch queue full, removing lowest priority "
270 "oldest packet, addr: %#x", it->pfInfo.getAddr());
271 delete it->pkt;
272 pfq.erase(it);
273 }
274
275 Tick pf_time = curTick() + clockPeriod() * latency;
276 DPRINTF(HWPrefetch, "Prefetch queued. "
277 "addr:%#x priority: %3d tick:%lld.\n",
278 target_addr, priority, pf_time);
279
280 /* Create the packet and find the spot to insert it */
281 DeferredPacket dpp(new_pfi, pf_time, pf_pkt, priority);
282 if (pfq.size() == 0) {
283 pfq.emplace_back(dpp);
284 } else {
285 iterator it = pfq.end();
286 do {
287 --it;
288 } while (it != pfq.begin() && dpp > *it);
289 /* If we reach the head, we have to see if the new element is new head
290 * or not */
291 if (it == pfq.begin() && dpp <= *it)
292 it++;
293 pfq.insert(it, dpp);
294 }
295}
|