Cache with finely granular locked-down regions
AssigneeNational Semiconductor Corporation
InventorDaniel W. Green
Life of this patent
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Abstract
A cache has programmable, finely ganular, locked-down regions within a way or way(s) so that the contents of the locked-down regions are not evicted. The finely granular locked-down regions need not be contiguous and are programmed as either "locked-valid" or "locked-invalid" to provide general purpose memory that is local and private to the processor or for masking defected cache lines or portions thereof. Finely granular, programmable spatial regions of the cache that are locked-down are preferably, although not exclusively, programmed through two additional states to the standard MESI (Modified, Exclusive, Shared, Invalid) protocol for multipurpose cache coherency.
Claims15
A cache with finely granular, programmable, locked-down regions comprising:
- (a) a set associative array, each set having a plurality of lines, each line having at least one tag;
- and,
- (b) the at least one tag having a field capable of indicating that at least a portion of the line is locked-down to prevent eviction and validity of each line or portion thereof.
A method for programmably locking-down finely granular regions in a cache comprising the steps of:
- (a) caching data in a set associative array, each set having a plurality of lines, each line having at least one tag;
- and,
- (b) programming a field in the at least one tag to indicate that at least a portion of the line is locked-down to prevent eviction and indicating validity of each line or portion thereof.
In a computer having a motherboard, a processor having an internal cache, and system memory external to the processor, a method for programmably locking-down finely granular regions in the cache comprising the steps of:
- (a) retrieving instructions from system memory;
- (b) executing the instructions with the processor;
- (c) caching instructions and data in the cache, the cache being a set associative array with each set having a plurality of lines and each line having at least one tag;
- and,
- (d) responsive to predetermined instructions, programming a field in the at least one tag indicating that at least a portion of the line is locked-down to prevent eviction and indicating validity of each line or portion thereof.
Dependencies are inferred from the claim text.