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(Updated 2011-01-12 22:42:07.876214) Review request for Default. Summary ------- The purpose of this patch is to change the way CacheMemory interfaces with coherence protocols. Currently, whenever a cache controller (defined in the protocol under consideration) needs to carry out any operation on a cache block, it looks up the tag hash map and figures out whether or not the block exists in the cache. In case it does exist, the operation is carried out (which requires another lookup). Over a single clock cycle, multiple such lookups take place as observed through profiling of different protocols. It was seen that the tag lookup takes anything from 10% to 20% of the simulation time. In order to reduce this time, this patch is being posted. The CacheMemory class now will have a function that will return pointer to a cache block entry, instead of a reference (though the function that returns the reference has been retained currently). Functions have been introduced for setting/unsetting a pointer and check its pointer. Similar changes have been carried out for Transaction Buffer entries as well. Note that changes are required to both SLICC and the protocol files. This patch carries out changes to SLICC and committing this patch alone, I believe, will ___break___ all the protocols. I am working on patching the protocols as well. This patch is being put to get feed back from other developers. Diffs (updated) ----- src/mem/protocol/MOESI_CMP_directory-L1cache.sm c6bc8fe81e79 src/mem/protocol/MOESI_CMP_directory-L2cache.sm c6bc8fe81e79 src/mem/protocol/MOESI_CMP_directory-dir.sm c6bc8fe81e79 src/mem/protocol/MOESI_CMP_directory-dma.sm c6bc8fe81e79 Diff: http://reviews.m5sim.org/r/358/diff Testing ------- I have tested these changes using the MOESI_CMP_directory and MI protocols. Thanks, Nilay
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