Patent ID: 6321293
Filing Date: 2001-11-20
Classification: G06F,G09G

Abstract:
A hierarchical caching method for standard disk I/O caching in a personal computer system having RAM and a storage disk, comprising the steps of:allocating a buffer from the RAM;intercepting disk page I/O requests;upon the interception of a disk page I/O request, if the intercepted I/O request is a read request, determining if the page to be read is already in the buffer and if so, decompressing the contents of the page into a RAM memory location specified for the page contents in the read request;if the intercepted I/O request is a read request, and the page to be read is not already in the buffer, or if the intercepted I/O request is a write request:determining if sufficient space in the buffer is available to hold the page data to be read or written;if sufficient space is available, copying the contents of the read or written page to the buffer;determining the compressibility of the contents of the page by pre-compressing a small portion thereof; andif the compression ratio for the small portion is at least two to one, compressing the read or written page in cache, otherwise allowing the operating system to cache the page contents in its normal manner.