Patent ID: 6243742
Filing Date: 2001-06-05
Classification: G06F

Abstract:
In a computer network having a first plurality of nodes coupled to a common network infrastructure and a distributed shared memory distributed among said first plurality of nodes, a method for permitting a first node of said computer network to access a copy of a memory block of a memory module that has a home node different from said first node in said computer network, said home node having a partial directory cache that has fewer directory cache entries than a total number of memory blocks in said memory module, said method comprising:receiving via said common network infrastructure at said home node from said first node a first memory access request for said memory block;in response to detecting directory states representing states of copies of said memory block in said first plurality of nodes are cached in a directory cache entry of said partial directory cache, servicing said first memory access request using a directory protocol by consulting said directory cache entry to determine which node in said computer network currently possesses a first valid copy of said memory block; andin response to detecting said directory states related to said memory block are not cached in said partial directory cache, servicing said first memory access request using a directory-less protocol.