diff options
Diffstat (limited to 'src/mem/cache/coherence/simple_coherence.hh')
-rw-r--r-- | src/mem/cache/coherence/simple_coherence.hh | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/src/mem/cache/coherence/simple_coherence.hh b/src/mem/cache/coherence/simple_coherence.hh new file mode 100644 index 000000000..71d8f36f4 --- /dev/null +++ b/src/mem/cache/coherence/simple_coherence.hh @@ -0,0 +1,161 @@ +/* + * Copyright (c) 2003-2005 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: Erik Hallnor + * Ron Dreslinski + */ + +/** + * @file + * Declaration of a simple coherence policy. + */ + +#ifndef __SIMPLE_COHERENCE_HH__ +#define __SIMPLE_COHERENCE_HH__ + +#include <string> + +#include "mem/packet.hh" +#include "mem/cache/cache_blk.hh" +#include "mem/cache/miss/mshr_queue.hh" +#include "mem/cache/coherence/coherence_protocol.hh" + +class BaseCache; + +/** + * A simple MP coherence policy. This policy assumes an atomic bus and only one + * level of cache. + */ +class SimpleCoherence +{ + protected: + /** Pointer to the parent cache. */ + BaseCache *cache; + /** Pointer to the coherence protocol. */ + CoherenceProtocol *protocol; + + public: + /** + * Construct and initialize this coherence policy. + * @param _protocol The coherence protocol to use. + */ + SimpleCoherence(CoherenceProtocol *_protocol) + : protocol(_protocol) + { + } + + /** + * Set the pointer to the parent cache. + * @param _cache The parent cache. + */ + void setCache(BaseCache *_cache) + { + cache = _cache; + } + + /** + * Register statistics. + * @param name The name to prepend to stat descriptions. + */ + void regStats(const std::string &name) + { + } + + /** + * This policy does not forward invalidates, return NULL. + * @return NULL. + */ + Packet * getPacket() + { + return NULL; + } + + /** + * Return the proper state given the current state and the bus response. + * @param pkt The bus response. + * @param current The current block state. + * @return The new state. + */ + CacheBlk::State getNewState(Packet * &pkt, CacheBlk::State current) + { + return protocol->getNewState(pkt, current); + } + + /** + * Handle snooped bus requests. + * @param pkt The snooped bus request. + * @param blk The cache block corresponding to the request, if any. + * @param mshr The MSHR corresponding to the request, if any. + * @param new_state Return the new state for the block. + */ + bool handleBusRequest(Packet * &pkt, CacheBlk *blk, MSHR *mshr, + CacheBlk::State &new_state) + { +// assert(mshr == NULL); +//Got rid of, there could be an MSHR, but it can't be in service + if (blk != NULL) + { + if (pkt->cmd != Packet::Writeback) { + return protocol->handleBusRequest(cache, pkt, blk, mshr, + new_state); + } + else { //It is a writeback, must be ownership protocol, just keep state + new_state = blk->status; + } + } + return false; + } + + /** + * Get the proper bus command for the given command and status. + * @param cmd The request's command. + * @param state The current state of the cache block. + * @return The proper bus command, as determined by the protocol. + */ + Packet::Command getBusCmd(Packet::Command &cmd, CacheBlk::State state) + { + if (cmd == Packet::Writeback) return Packet::Writeback; + return protocol->getBusCmd(cmd, state); + } + + /** + * Return true if this coherence policy can handle fast cache writes. + */ + bool allowFastWrites() { return false; } + + bool hasProtocol() { return true; } +}; + +#endif //__SIMPLE_COHERENCE_HH__ + + + + + + + + |