LEAST-RECENTLY-USED (LRU) TO FIRST-DIRTY-MEMBER DISTANCE-MAINTAINING CACHE CLEANING SCHEDULER

摘要

A technique for scheduling cache cleaning operations maintains a clean distance between a set of least-recently-used (LRU) clean lines and the LRU dirty (modified) line for each congruence class in the cache. The technique is generally employed at a victim cache at the highest-order level of the cache memory hierarchy, so that write-backs to system memory are scheduled to avoid having to generate a write-back in response to a cache miss in the next lower-order level of the cache memory hierarchy. The clean distance can be determined by counting all of the LRU clean lines in each congruence class that have a reference count that is less than or equal to the reference count of the LRU dirty line.

主权项

1. A method of scheduling cache write-back operations, the method comprising:
for each congruence class of a cache memory, determining an indication of a number of line allocations that can be supported by the current state of the congruence class without causing a write-back of a dirty line; comparing the indication to a specified clean distance value to determine when to schedule write-backs of dirty lines of the cache memory; responsive to the comparing determining that write-backs should be scheduled, scheduling the write-backs of one or more of the dirty lines.