US 8,135,910 B2 · Bandwidth of a cache directory by slicing the cache directory into two smaller cache directories and replicating snooping logic for each sliced cache directory

Abstract

A cache, system and method for improving the snoop bandwidth of a cache directory. A cache directory may be sliced into two smaller cache directories each with its own snooping logic. By having two cache directories that can be accessed simultaneously, the bandwidth can be essentially doubled. Furthermore, a “frequency matcher” may shift the cycle speed to a lower speed upon receiving snoop addresses from the interconnect thereby slowing down the rate at which requests are transmitted to the dispatch pipelines. Each dispatch pipeline is coupled to a sliced cache directory and is configured to search the cache directory to determine if data at the received addresses is stored in the cache memory. As a result of slowing down the rate at which requests are transmitted to the dispatch pipelines and accessing the two sliced cache directories simultaneously, the bandwidth or throughput of the cache directory may be improved.

Claims3

Dependent claims

A method for improving the bandwidth of a cache directory comprising the steps of:

receiving a first and a second address;
reading a value in a bit in each of said first and said second address;
determining which of a first and a second cache directory to search for said first and said second address based on said value read in said first and said second address;
wherein said first cache directory is comprised of entries indicating data stored in a cache memory at addresses with a value of zero at said bit, wherein said second cache directory is comprised of entries indicating data stored in said cache memory at addresses with a value of a logical one at said bit;
sending said first address to a first multiplexer by a first unit when said value read in both said first and said second address is zero and said second address is selected to be transmitted to a second unit on a bypass path, wherein said first unit is configured to shift a cycle speed to a lower speed, wherein said second unit is configured to shift said cycle speed to a higher speed.

2 more elements

Dependencies are inferred from the claim text.

Bandwidth of a cache directory by slicing the cache directory into two smaller cache directories and replicating snooping logic for each sliced cache directory

Life of this patent

Bandwidth of a cache directory by slicing the cache directory into two smaller cache directories and replicating snooping logic for each sliced cache directory

Life of this patent

Abstract

Claims3