71aca6d29e
Allow lower-level caches (e.g., L2 or L3) to pass exclusive copies to higher levels (e.g., L1). This eliminates a lot of unnecessary upgrade transactions on read-write sequences to non-shared data. Also some cleanup of MSHR coherence handling and multiple bug fixes.
331 lines
11 KiB
C++
331 lines
11 KiB
C++
/*
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* Copyright (c) 2002-2005 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: Erik Hallnor
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* Dave Greene
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* Steve Reinhardt
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* Ron Dreslinski
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*/
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/**
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* @file
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* Describes a cache based on template policies.
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*/
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#ifndef __CACHE_HH__
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#define __CACHE_HH__
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#include "base/misc.hh" // fatal, panic, and warn
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#include "mem/cache/base.hh"
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#include "mem/cache/blk.hh"
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#include "mem/cache/mshr.hh"
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#include "sim/eventq.hh"
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//Forward decleration
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class BasePrefetcher;
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/**
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* A template-policy based cache. The behavior of the cache can be altered by
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* supplying different template policies. TagStore handles all tag and data
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* storage @sa TagStore.
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*/
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template <class TagStore>
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class Cache : public BaseCache
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{
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public:
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/** Define the type of cache block to use. */
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typedef typename TagStore::BlkType BlkType;
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/** A typedef for a list of BlkType pointers. */
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typedef typename TagStore::BlkList BlkList;
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protected:
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class CpuSidePort : public CachePort
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{
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public:
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CpuSidePort(const std::string &_name,
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Cache<TagStore> *_cache,
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const std::string &_label);
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// BaseCache::CachePort just has a BaseCache *; this function
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// lets us get back the type info we lost when we stored the
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// cache pointer there.
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Cache<TagStore> *myCache() {
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return static_cast<Cache<TagStore> *>(cache);
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}
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virtual void getDeviceAddressRanges(AddrRangeList &resp,
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bool &snoop);
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virtual bool recvTiming(PacketPtr pkt);
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virtual Tick recvAtomic(PacketPtr pkt);
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virtual void recvFunctional(PacketPtr pkt);
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};
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class MemSidePort : public CachePort
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{
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public:
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MemSidePort(const std::string &_name,
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Cache<TagStore> *_cache,
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const std::string &_label);
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// BaseCache::CachePort just has a BaseCache *; this function
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// lets us get back the type info we lost when we stored the
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// cache pointer there.
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Cache<TagStore> *myCache() {
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return static_cast<Cache<TagStore> *>(cache);
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}
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void sendPacket();
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void processSendEvent();
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virtual void getDeviceAddressRanges(AddrRangeList &resp,
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bool &snoop);
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virtual bool recvTiming(PacketPtr pkt);
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virtual void recvRetry();
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virtual Tick recvAtomic(PacketPtr pkt);
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virtual void recvFunctional(PacketPtr pkt);
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typedef EventWrapper<MemSidePort, &MemSidePort::processSendEvent>
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SendEvent;
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};
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/** Tag and data Storage */
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TagStore *tags;
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/** Prefetcher */
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BasePrefetcher *prefetcher;
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/** Temporary cache block for occasional transitory use */
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BlkType *tempBlock;
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/**
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* This cache should allocate a block on a line-sized write miss.
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*/
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const bool doFastWrites;
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/**
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* Notify the prefetcher on every access, not just misses.
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*/
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const bool prefetchOnAccess;
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/**
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* Does all the processing necessary to perform the provided request.
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* @param pkt The memory request to perform.
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* @param lat The latency of the access.
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* @param writebacks List for any writebacks that need to be performed.
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* @param update True if the replacement data should be updated.
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* @return Boolean indicating whether the request was satisfied.
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*/
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bool access(PacketPtr pkt, BlkType *&blk,
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int &lat, PacketList &writebacks);
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/**
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*Handle doing the Compare and Swap function for SPARC.
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*/
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void cmpAndSwap(BlkType *blk, PacketPtr pkt);
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/**
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* Find a block frame for new block at address addr, assuming that
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* the block is not currently in the cache. Append writebacks if
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* any to provided packet list. Return free block frame. May
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* return NULL if there are no replaceable blocks at the moment.
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*/
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BlkType *allocateBlock(Addr addr, PacketList &writebacks);
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/**
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* Populates a cache block and handles all outstanding requests for the
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* satisfied fill request. This version takes two memory requests. One
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* contains the fill data, the other is an optional target to satisfy.
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* @param pkt The memory request with the fill data.
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* @param blk The cache block if it already exists.
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* @param writebacks List for any writebacks that need to be performed.
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* @return Pointer to the new cache block.
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*/
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BlkType *handleFill(PacketPtr pkt, BlkType *blk,
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PacketList &writebacks);
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void satisfyCpuSideRequest(PacketPtr pkt, BlkType *blk,
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bool deferred_response = false,
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bool pending_downgrade = false);
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bool satisfyMSHR(MSHR *mshr, PacketPtr pkt, BlkType *blk);
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void doTimingSupplyResponse(PacketPtr req_pkt, uint8_t *blk_data,
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bool already_copied, bool pending_inval);
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/**
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* Sets the blk to the new state.
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* @param blk The cache block being snooped.
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* @param new_state The new coherence state for the block.
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*/
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void handleSnoop(PacketPtr ptk, BlkType *blk,
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bool is_timing, bool is_deferred, bool pending_inval);
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/**
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* Create a writeback request for the given block.
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* @param blk The block to writeback.
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* @return The writeback request for the block.
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*/
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PacketPtr writebackBlk(BlkType *blk);
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public:
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/** Instantiates a basic cache object. */
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Cache(const Params *p, TagStore *tags, BasePrefetcher *prefetcher);
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virtual Port *getPort(const std::string &if_name, int idx = -1);
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virtual void deletePortRefs(Port *p);
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void regStats();
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/**
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* Performs the access specified by the request.
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* @param pkt The request to perform.
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* @return The result of the access.
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*/
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bool timingAccess(PacketPtr pkt);
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/**
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* Performs the access specified by the request.
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* @param pkt The request to perform.
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* @return The result of the access.
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*/
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Tick atomicAccess(PacketPtr pkt);
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/**
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* Performs the access specified by the request.
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* @param pkt The request to perform.
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* @return The result of the access.
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*/
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void functionalAccess(PacketPtr pkt, CachePort *incomingPort,
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CachePort *otherSidePort);
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/**
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* Handles a response (cache line fill/write ack) from the bus.
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* @param pkt The request being responded to.
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*/
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void handleResponse(PacketPtr pkt);
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/**
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* Snoops bus transactions to maintain coherence.
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* @param pkt The current bus transaction.
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*/
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void snoopTiming(PacketPtr pkt);
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/**
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* Snoop for the provided request in the cache and return the estimated
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* time of completion.
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* @param pkt The memory request to snoop
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* @return The estimated completion time.
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*/
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Tick snoopAtomic(PacketPtr pkt);
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/**
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* Squash all requests associated with specified thread.
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* intended for use by I-cache.
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* @param threadNum The thread to squash.
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*/
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void squash(int threadNum);
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/**
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* Generate an appropriate downstream bus request packet for the
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* given parameters.
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* @param cpu_pkt The upstream request that needs to be satisfied.
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* @param blk The block currently in the cache corresponding to
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* cpu_pkt (NULL if none).
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* @param needsExclusive Indicates that an exclusive copy is required
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* even if the request in cpu_pkt doesn't indicate that.
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* @return A new Packet containing the request, or NULL if the
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* current request in cpu_pkt should just be forwarded on.
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*/
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PacketPtr getBusPacket(PacketPtr cpu_pkt, BlkType *blk,
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bool needsExclusive);
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/**
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* Return the next MSHR to service, either a pending miss from the
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* mshrQueue, a buffered write from the write buffer, or something
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* from the prefetcher. This function is responsible for
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* prioritizing among those sources on the fly.
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*/
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MSHR *getNextMSHR();
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/**
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* Selects an outstanding request to service. Called when the
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* cache gets granted the downstream bus in timing mode.
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* @return The request to service, NULL if none found.
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*/
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PacketPtr getTimingPacket();
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/**
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* Marks a request as in service (sent on the bus). This can have side
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* effect since storage for no response commands is deallocated once they
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* are successfully sent.
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* @param pkt The request that was sent on the bus.
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*/
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void markInService(MSHR *mshr, PacketPtr pkt = 0);
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/**
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* Perform the given writeback request.
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* @param pkt The writeback request.
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*/
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void doWriteback(PacketPtr pkt);
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/**
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* Return whether there are any outstanding misses.
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*/
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bool outstandingMisses() const
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{
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return mshrQueue.allocated != 0;
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}
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CacheBlk *findBlock(Addr addr) {
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return tags->findBlock(addr);
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}
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bool inCache(Addr addr) {
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return (tags->findBlock(addr) != 0);
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}
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bool inMissQueue(Addr addr) {
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return (mshrQueue.findMatch(addr) != 0);
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}
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/**
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* Find next request ready time from among possible sources.
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*/
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Tick nextMSHRReadyTime();
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};
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#endif // __CACHE_HH__
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