Cache: Fix the LRU policy for classic memory hierarchy

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Submitter:	Lena Olson
Repository:	gem5
Branch:	default
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Description

Changeset 9071:7526dad15b35
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Cache: Fix the LRU policy for classic memory hierarchy

The LRU policy always evicted the least recently touched way, even if it
contained valid data and another way was invalid, as can happen if a block has
been invalidated by coherance.  This can result in caches never warming up even
though they are replacing blocks.  This modifies the LRU policy to move blocks
to LRU position on invalidation.

Testing Done

Issue Summary

Description	From	Last Updated	Status
There must be a way to do this without the loop.	Ali Saidi	June 18, 2012, 12:23 p.m.	Open

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src/mem/cache/tags/cacheset.cc (Diff revision 1)

There must be a way to do this without the loop.

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Steve Reinhardt June 18, 2012, 3:36 p.m. (June 18, 2012, 3:36 p.m.)

It's just copied from moveToHead(), so I don't think it's fair to make Lena fix it.  Also, the LRU list is just stored as an array, so you do have to shift pointers (hence the loop).  Both versions could stand to be streamlined a bit though, I agree.

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Issue Summary

Status: Closed (submitted)