Patent ID: 6226718
Filing Date: 2001-05-01
Classification: G06F

Abstract:
A method for avoiding livelocks due to stale exclusive/modified directory entries within a non-uniform memory access (NUMA) computer system, wherein said NUMA computer system includes at least two nodes coupled to an interconnect and each of said at least two nodes includes a local system memory, said method comprising the steps of:in response to an attempt by a processor of a first node to read a cache line at a time substantially simultaneously to an attempt by a processor of a second node to access said cache line, wherein said cache line has been silently cast out from a cache memory within said second node even though a coherency directory within said first node still indicates said cache line is held exclusively or modified at said second node, allowing a directory within said second node to be updated from a Pending-Modified state to a Pending-Shared state after the receipt of the request from said first node is received with a clean response; andallowing said processor of said first node to access said cache line.