Data coherency management

摘要

A data processing systems employing a coherent memory system comprises multiple main cache memories. An inclusive snoop directory memory stores directory lines. Each directory line includes a directory tag and multiple snoop vectors. Each snoop vector relates to a span of memory addresses corresponding to the cache line size within the main cache memories.

主权项

1. Apparatus for processing data comprising:
a plurality of main cache memories each having a plurality of main cache lines; an inclusive snoop directory memory having a plurality of directory lines, each of said directory lines respectively storing:
(i) a given directory tag value indicative of a contiguous range of memory address values with a given span corresponding in size to N main cache lines, where N is an integer greater than one; and(ii) N snoop vectors, each of said N snoop vectors indicating at least that, for a respective one of N memory address sub-regions within said given span, one or more of said plurality of main cache memories is logged as storing data corresponding to said respective one of N memory address sub-regions, wherein: said inclusive snoop directory memory comprises A directory lines, where A is a positive integer; said plurality of main cache memories comprise X cache memories, where X is an integer greater than one; each of said plurality of main cache memories comprises B main cache lines, where B is a positive integer; and N*A is greater than X*B.