Semi-associative cache with MRU/LRU replacement

Details Semi-associative cache with MRU/LRU replacement Semi-associative cache with MRU/LRU replacement

1996-01-26

1998-02-03

Kim, Matthew M.

395455, 395471, G06F 1208

Patent

active

057154279

ABSTRACT:
A cache memory uses content-addressable tag-compare arrays (CAM) to determine if a match occurs. In a semi-associative instruction cache, with the CAM and eight cache lines grouped together to form camlets, a binary index is used to address one camlet in the cache array, and the effective address tag match is used to select a potential line within the camlet in accessing data stored in the cache array. Since an E-tag match causes that cache line's wordline to activate, proper cache operation requires that no two (or more) E-tags within a camlet have the same match criteria (ECAM entry); the invalidation of entries is done to prevent this from happening. Due to the mapping of the effective address into the E-tag CAM and the camlet binary index, addresses that are 1-Meg apart point to the same camlet and have the same ECAM tag. The method thus employs a semi-associative cache having cache lines configured in camlets of, for example, eight lines per camlet. An LRU indication is stored in each camlet showing which line was least-recently-used. Upon occurrence of a cache replacement operation, it is determined whether or not a replacement line has a tag matching a line that is already in the camlet, and, if so, this line is invalidated and it is indicated to be the least-recently-used line. The next replacement goes to this line, whereas otherwise it would have appeared to be the most-recently-used since its wordline went high for the invalidate operation.

REFERENCES:
patent: 5073891 (1991-12-01), Patel
patent: 5325511 (1994-06-01), Collins et al.
patent: 5467460 (1995-11-01), Patel
patent: 5584013 (1996-12-01), Cheong et al.
patent: 5638531 (1997-06-01), Crump et al.

Affiliated with

Also associated with

Rating

Semi-associative cache with MRU/LRU replacement does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Semi-associative cache with MRU/LRU replacement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semi-associative cache with MRU/LRU replacement will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-671373