queued.cc revision 10922:5ee72f4b2931
1/* 2 * Copyright (c) 2014 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 "debug/HWPrefetch.hh" 41#include "mem/cache/prefetch/queued.hh" 42#include "mem/cache/base.hh" 43 44QueuedPrefetcher::QueuedPrefetcher(const QueuedPrefetcherParams *p) 45 : BasePrefetcher(p), queueSize(p->queue_size), latency(p->latency), 46 queueSquash(p->queue_squash), queueFilter(p->queue_filter), 47 cacheSnoop(p->cache_snoop), tagPrefetch(p->tag_prefetch) 48{ 49 50} 51 52QueuedPrefetcher::~QueuedPrefetcher() 53{ 54 // Delete the queued prefetch packets 55 for (DeferredPacket &p : pfq) { 56 delete p.pkt->req; 57 delete p.pkt; 58 } 59} 60 61Tick 62QueuedPrefetcher::notify(const PacketPtr &pkt) 63{ 64 // Verify this access type is observed by prefetcher 65 if (observeAccess(pkt)) { 66 Addr blk_addr = pkt->getAddr() & ~(Addr)(blkSize - 1); 67 bool is_secure = pkt->isSecure(); 68 69 // Squash queued prefetches if demand miss to same line 70 if (queueSquash) { 71 auto itr = pfq.begin(); 72 while (itr != pfq.end()) { 73 if (itr->pkt->getAddr() == blk_addr && 74 itr->pkt->isSecure() == is_secure) { 75 delete itr->pkt->req; 76 delete itr->pkt; 77 itr = pfq.erase(itr); 78 } else { 79 ++itr; 80 } 81 } 82 83 if (pfq.empty()) 84 cache->deassertMemSideBusRequest(BaseCache::Request_PF); 85 } 86 87 // Calculate prefetches given this access 88 std::vector<Addr> addresses; 89 calculatePrefetch(pkt, addresses); 90 91 // Queue up generated prefetches 92 for (Addr pf_addr : addresses) { 93 94 // Block align prefetch address 95 pf_addr = pf_addr & ~(Addr)(blkSize - 1); 96 97 pfIdentified++; 98 DPRINTF(HWPrefetch, "Found a pf candidate addr: %#x, " 99 "inserting into prefetch queue.\n", pf_addr); 100 101 if (queueFilter && inPrefetch(pf_addr, is_secure)) { 102 pfBufferHit++; 103 DPRINTF(HWPrefetch, "Prefetch addr already in " 104 "prefetch queue\n"); 105 continue; 106 } 107 108 if (cacheSnoop && (inCache(pf_addr, is_secure) || 109 inMissQueue(pf_addr, is_secure))) { 110 pfInCache++; 111 DPRINTF(HWPrefetch, "Dropping redundant in " 112 "cache/MSHR prefetch addr:%#x\n", pf_addr); 113 continue; 114 } 115 116 // Create a prefetch memory request 117 Request *pf_req = 118 new Request(pf_addr, blkSize, 0, masterId); 119 120 if (is_secure) { 121 pf_req->setFlags(Request::SECURE); 122 } 123 pf_req->taskId(ContextSwitchTaskId::Prefetcher); 124 PacketPtr pf_pkt = new Packet(pf_req, MemCmd::HardPFReq); 125 pf_pkt->allocate(); 126 127 if (pkt->req->hasContextId()) { 128 pf_req->setThreadContext(pkt->req->contextId(), 129 pkt->req->threadId()); 130 } 131 132 if (tagPrefetch && pkt->req->hasPC()) { 133 // Tag prefetch packet with accessing pc 134 pf_pkt->req->setPC(pkt->req->getPC()); 135 } 136 137 // Verify prefetch buffer space for request 138 if (pfq.size() == queueSize) { 139 pfRemovedFull++; 140 PacketPtr old_pkt = pfq.begin()->pkt; 141 DPRINTF(HWPrefetch, "Prefetch queue full, removing " 142 "oldest packet addr: %#x", old_pkt->getAddr()); 143 delete old_pkt->req; 144 delete old_pkt; 145 pfq.pop_front(); 146 } 147 148 Tick pf_time = curTick() + clockPeriod() * latency; 149 DPRINTF(HWPrefetch, "Prefetch queued. " 150 "addr:%#x tick:%lld.\n", pf_addr, pf_time); 151 152 pfq.emplace_back(pf_time, pf_pkt); 153 } 154 } 155 156 return pfq.empty() ? MaxTick : pfq.front().tick; 157} 158 159PacketPtr 160QueuedPrefetcher::getPacket() 161{ 162 DPRINTF(HWPrefetch, "Requesting a prefetch to issue.\n"); 163 164 if (pfq.empty()) { 165 DPRINTF(HWPrefetch, "No hardware prefetches available.\n"); 166 return NULL; 167 } 168 169 PacketPtr pkt = pfq.begin()->pkt; 170 pfq.pop_front(); 171 172 pfIssued++; 173 assert(pkt != NULL); 174 DPRINTF(HWPrefetch, "Generating prefetch for %#x.\n", pkt->getAddr()); 175 return pkt; 176} 177 178bool 179QueuedPrefetcher::inPrefetch(Addr address, bool is_secure) const 180{ 181 for (const DeferredPacket &dp : pfq) { 182 if (dp.pkt->getAddr() == address && 183 dp.pkt->isSecure() == is_secure) return true; 184 } 185 186 return false; 187} 188 189void 190QueuedPrefetcher::regStats() 191{ 192 BasePrefetcher::regStats(); 193 194 pfIdentified 195 .name(name() + ".pfIdentified") 196 .desc("number of prefetch candidates identified"); 197 198 pfBufferHit 199 .name(name() + ".pfBufferHit") 200 .desc("number of redundant prefetches already in prefetch queue"); 201 202 pfInCache 203 .name(name() + ".pfInCache") 204 .desc("number of redundant prefetches already in cache/mshr dropped"); 205 206 pfRemovedFull 207 .name(name() + ".pfRemovedFull") 208 .desc("number of prefetches dropped due to prefetch queue size"); 209 210 pfSpanPage 211 .name(name() + ".pfSpanPage") 212 .desc("number of prefetches not generated due to page crossing"); 213} 214