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/*
* Copyright (c) 2005 The Regents of The University of Michigan
* 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.
*
* Authors: Ron Dreslinski
*/
/**
* @file
* Describes a ghb prefetcher based on template policies.
*/
#ifndef __MEM_CACHE_PREFETCH_GHB_PREFETCHER_HH__
#define __MEM_CACHE_PREFETCH_GHB_PREFETCHER_HH__
#include "base/misc.hh" // fatal, panic, and warn
#include "mem/cache/prefetch/prefetcher.hh"
/**
* A template-policy based cache. The behavior of the cache can be altered by
* supplying different template policies. TagStore handles all tag and data
* storage @sa TagStore. Buffering handles all misses and writes/writebacks
* @sa MissQueue. Coherence handles all coherence policy details @sa
* UniCoherence, SimpleMultiCoherence.
*/
template <class TagStore, class Buffering>
class GHBPrefetcher : public Prefetcher<TagStore, Buffering>
{
protected:
Buffering* mq;
TagStore* tags;
Addr second_last_miss_addr[64/*MAX_CPUS*/];
Addr last_miss_addr[64/*MAX_CPUS*/];
Tick latency;
int degree;
bool useCPUId;
public:
GHBPrefetcher(int size, bool pageStop, bool serialSquash,
bool cacheCheckPush, bool onlyData,
Tick latency, int degree, bool useCPUId)
:Prefetcher<TagStore, Buffering>(size, pageStop, serialSquash,
cacheCheckPush, onlyData),
latency(latency), degree(degree), useCPUId(useCPUId)
{
}
~GHBPrefetcher() {}
void calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses,
std::list<Tick> &delays)
{
Addr blkAddr = pkt->getAddr() & ~(Addr)(this->blkSize-1);
int cpuID = pkt->req->getCpuNum();
if (!useCPUId) cpuID = 0;
int new_stride = blkAddr - last_miss_addr[cpuID];
int old_stride = last_miss_addr[cpuID] -
second_last_miss_addr[cpuID];
second_last_miss_addr[cpuID] = last_miss_addr[cpuID];
last_miss_addr[cpuID] = blkAddr;
if (new_stride == old_stride) {
for (int d=1; d <= degree; d++) {
Addr newAddr = blkAddr + d * new_stride;
if (this->pageStop &&
(blkAddr & ~(TheISA::VMPageSize - 1)) !=
(newAddr & ~(TheISA::VMPageSize - 1)))
{
//Spanned the page, so now stop
this->pfSpanPage += degree - d + 1;
return;
}
else
{
addresses.push_back(newAddr);
delays.push_back(latency);
}
}
}
}
};
#endif // __MEM_CACHE_PREFETCH_GHB_PREFETCHER_HH__
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