| /** |
| * Copyright (c) 2018 Metempsy Technology Consulting |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer; |
| * redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution; |
| * neither the name of the copyright holders nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "mem/cache/prefetch/sbooe.hh" |
| |
| #include "debug/HWPrefetch.hh" |
| #include "params/SBOOEPrefetcher.hh" |
| |
| namespace gem5 |
| { |
| |
| GEM5_DEPRECATED_NAMESPACE(Prefetcher, prefetch); |
| namespace prefetch |
| { |
| |
| SBOOE::SBOOE(const SBOOEPrefetcherParams &p) |
| : Queued(p), |
| sequentialPrefetchers(p.sequential_prefetchers), |
| scoreThreshold((p.sandbox_entries*p.score_threshold_pct)/100), |
| latencyBuffer(p.latency_buffer_size), |
| averageAccessLatency(0), latencyBufferSum(0), |
| bestSandbox(NULL), |
| accesses(0) |
| { |
| // Initialize a sandbox for every sequential prefetcher between |
| // -1 and the number of sequential prefetchers defined |
| for (int i = 0; i < sequentialPrefetchers; i++) { |
| sandboxes.push_back(Sandbox(p.sandbox_entries, i-1)); |
| } |
| } |
| |
| void |
| SBOOE::Sandbox::access(Addr addr, Tick tick) |
| { |
| // Search for the address in the FIFO queue to update the score |
| for (const SandboxEntry &entry: entries) { |
| if (entry.valid && entry.line == addr) { |
| sandboxScore++; |
| if (entry.expectedArrivalTick > curTick()) { |
| lateScore++; |
| } |
| } |
| } |
| |
| // Insert new access in this sandbox |
| SandboxEntry entry; |
| entry.valid = true; |
| entry.line = addr + stride; |
| entry.expectedArrivalTick = tick; |
| entries.push_back(entry); |
| } |
| |
| bool |
| SBOOE::access(Addr access_line) |
| { |
| for (Sandbox &sb : sandboxes) { |
| sb.access(access_line, curTick() + averageAccessLatency); |
| |
| if (bestSandbox == NULL || sb.score() > bestSandbox->score()) { |
| bestSandbox = &sb; |
| } |
| } |
| |
| accesses++; |
| |
| return (accesses >= sandboxes.size()); |
| } |
| |
| void |
| SBOOE::notifyFill(const PacketPtr& pkt) |
| { |
| // (1) Look for the address in the demands list |
| // (2) Calculate the elapsed cycles until it was filled (curTick) |
| // (3) Insert the latency into the latency buffer (FIFO) |
| // (4) Calculate the new average access latency |
| |
| auto it = demandAddresses.find(pkt->getAddr()); |
| |
| if (it != demandAddresses.end()) { |
| Tick elapsed_ticks = curTick() - it->second; |
| |
| if (latencyBuffer.full()) { |
| latencyBufferSum -= latencyBuffer.front(); |
| } |
| latencyBuffer.push_back(elapsed_ticks); |
| latencyBufferSum += elapsed_ticks; |
| |
| averageAccessLatency = latencyBufferSum / latencyBuffer.size(); |
| |
| demandAddresses.erase(it); |
| } |
| } |
| |
| void |
| SBOOE::calculatePrefetch(const PrefetchInfo &pfi, |
| std::vector<AddrPriority> &addresses) |
| { |
| const Addr pfi_addr = pfi.getAddr(); |
| const Addr pfi_line = pfi_addr >> lBlkSize; |
| |
| auto it = demandAddresses.find(pfi_addr); |
| |
| if (it == demandAddresses.end()) { |
| demandAddresses.insert(std::pair<Addr, Tick>(pfi_addr, curTick())); |
| } |
| |
| const bool evaluationFinished = access(pfi_line); |
| |
| if (evaluationFinished && bestSandbox->score() > scoreThreshold) { |
| Addr pref_line = pfi_line + bestSandbox->stride; |
| addresses.push_back(AddrPriority(pref_line << lBlkSize, 0)); |
| } |
| } |
| |
| } // namespace prefetch |
| } // namespace gem5 |