a928a438b8
Used cppclean to help identify useless includes and removed them. This involved erroneously included headers, but also cases where forward declarations could have been used rather than a full include.
222 lines
7.6 KiB
C++
222 lines
7.6 KiB
C++
/*
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* Copyright (c) 2012-2013, 2015 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Ron Dreslinski
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* Steve Reinhardt
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*/
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/**
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* @file
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* Stride Prefetcher template instantiations.
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*/
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#include "mem/cache/prefetch/stride.hh"
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#include "base/random.hh"
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#include "base/trace.hh"
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#include "debug/HWPrefetch.hh"
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StridePrefetcher::StridePrefetcher(const StridePrefetcherParams *p)
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: QueuedPrefetcher(p),
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maxConf(p->max_conf),
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threshConf(p->thresh_conf),
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minConf(p->min_conf),
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startConf(p->start_conf),
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pcTableAssoc(p->table_assoc),
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pcTableSets(p->table_sets),
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useMasterId(p->use_master_id),
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degree(p->degree),
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pcTable(pcTableAssoc, pcTableSets, name())
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{
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// Don't consult stride prefetcher on instruction accesses
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onInst = false;
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assert(isPowerOf2(pcTableSets));
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}
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StridePrefetcher::StrideEntry**
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StridePrefetcher::PCTable::allocateNewContext(int context)
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{
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auto res = entries.insert(std::make_pair(context,
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new StrideEntry*[pcTableSets]));
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auto it = res.first;
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chatty_assert(res.second, "Allocating an already created context\n");
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assert(it->first == context);
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DPRINTF(HWPrefetch, "Adding context %i with stride entries at %p\n",
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context, it->second);
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StrideEntry** entry = it->second;
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for (int s = 0; s < pcTableSets; s++) {
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entry[s] = new StrideEntry[pcTableAssoc];
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}
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return entry;
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}
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StridePrefetcher::PCTable::~PCTable() {
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for (auto entry : entries) {
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for (int s = 0; s < pcTableSets; s++) {
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delete[] entry.second[s];
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}
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delete[] entry.second;
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}
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}
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void
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StridePrefetcher::calculatePrefetch(const PacketPtr &pkt,
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std::vector<AddrPriority> &addresses)
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{
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if (!pkt->req->hasPC()) {
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DPRINTF(HWPrefetch, "Ignoring request with no PC.\n");
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return;
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}
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// Get required packet info
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Addr pkt_addr = pkt->getAddr();
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Addr pc = pkt->req->getPC();
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bool is_secure = pkt->isSecure();
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MasterID master_id = useMasterId ? pkt->req->masterId() : 0;
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// Lookup pc-based information
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StrideEntry *entry;
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if (pcTableHit(pc, is_secure, master_id, entry)) {
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// Hit in table
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int new_stride = pkt_addr - entry->lastAddr;
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bool stride_match = (new_stride == entry->stride);
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// Adjust confidence for stride entry
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if (stride_match && new_stride != 0) {
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if (entry->confidence < maxConf)
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entry->confidence++;
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} else {
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if (entry->confidence > minConf)
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entry->confidence--;
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// If confidence has dropped below the threshold, train new stride
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if (entry->confidence < threshConf)
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entry->stride = new_stride;
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}
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DPRINTF(HWPrefetch, "Hit: PC %x pkt_addr %x (%s) stride %d (%s), "
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"conf %d\n", pc, pkt_addr, is_secure ? "s" : "ns", new_stride,
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stride_match ? "match" : "change",
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entry->confidence);
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entry->lastAddr = pkt_addr;
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// Abort prefetch generation if below confidence threshold
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if (entry->confidence < threshConf)
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return;
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// Generate up to degree prefetches
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for (int d = 1; d <= degree; d++) {
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// Round strides up to atleast 1 cacheline
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int prefetch_stride = new_stride;
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if (abs(new_stride) < blkSize) {
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prefetch_stride = (new_stride < 0) ? -blkSize : blkSize;
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}
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Addr new_addr = pkt_addr + d * prefetch_stride;
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if (samePage(pkt_addr, new_addr)) {
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DPRINTF(HWPrefetch, "Queuing prefetch to %#x.\n", new_addr);
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addresses.push_back(AddrPriority(new_addr, 0));
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} else {
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// Record the number of page crossing prefetches generated
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pfSpanPage += degree - d + 1;
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DPRINTF(HWPrefetch, "Ignoring page crossing prefetch.\n");
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return;
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}
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}
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} else {
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// Miss in table
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DPRINTF(HWPrefetch, "Miss: PC %x pkt_addr %x (%s)\n", pc, pkt_addr,
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is_secure ? "s" : "ns");
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StrideEntry* entry = pcTableVictim(pc, master_id);
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entry->instAddr = pc;
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entry->lastAddr = pkt_addr;
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entry->isSecure= is_secure;
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entry->stride = 0;
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entry->confidence = startConf;
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}
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}
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inline Addr
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StridePrefetcher::pcHash(Addr pc) const
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{
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Addr hash1 = pc >> 1;
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Addr hash2 = hash1 >> floorLog2(pcTableSets);
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return (hash1 ^ hash2) & (Addr)(pcTableSets - 1);
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}
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inline StridePrefetcher::StrideEntry*
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StridePrefetcher::pcTableVictim(Addr pc, int master_id)
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{
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// Rand replacement for now
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int set = pcHash(pc);
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int way = random_mt.random<int>(0, pcTableAssoc - 1);
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DPRINTF(HWPrefetch, "Victimizing lookup table[%d][%d].\n", set, way);
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return &pcTable[master_id][set][way];
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}
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inline bool
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StridePrefetcher::pcTableHit(Addr pc, bool is_secure, int master_id,
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StrideEntry* &entry)
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{
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int set = pcHash(pc);
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StrideEntry* set_entries = pcTable[master_id][set];
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for (int way = 0; way < pcTableAssoc; way++) {
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// Search ways for match
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if (set_entries[way].instAddr == pc &&
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set_entries[way].isSecure == is_secure) {
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DPRINTF(HWPrefetch, "Lookup hit table[%d][%d].\n", set, way);
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entry = &set_entries[way];
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return true;
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}
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}
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return false;
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}
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StridePrefetcher*
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StridePrefetcherParams::create()
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{
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return new StridePrefetcher(this);
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}
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