Abstract: Provided are an apparatus and system to cache data in a first cache and a second cache that cache data from a shared memory in a local processor node, wherein the shared memory is accessible to at least one remote processor node. A cache controller writes a block to the second cache in response to determining that the block is more likely to be accessed by the local processor node than a remote processor node. The first cache controller writes the block to the shared memory in response to determining that the block is more likely to be accessed by the one of the at least one remote processor node than the local processor node without writing to the second cache.

Abstract: To reduce overhead for cache coherence for shared cache in multi-processor systems, adaptive granularity allows tracking shared data at a coarse granularity and unshared data at fine granularity. Processes for adaptive granularity select how large of an entry is required to track the coherence of a block based on its state. Shared blocks are tracked in coarse-grained region entries that include a sharer tracking bit vector and a bit vector that indicates which blocks are likely to be present in the system, but do not identify the owner of the block. Modified/unshared data is tracked in fine-grained entries that permit ownership tracking and exact location and invalidation of cache. Large caches where the majority of blocks are shared and not modified create less overhead by being tracked in the less costly coarse-grained region entries.

Abstract: Provided are an apparatus and system to cache data in a first cache and a second cache that cache data from a shared memory in a local processor node, wherein the shared memory is accessible to at least one remote processor node. A cache controller writes a block to the second cache in response to determining that the block is more likely to be accessed by the local processor node than a remote processor node. The first cache controller writes the block to the shared memory in response to determining that the block is more likely to be accessed by the one of the at least one remote processor node than the local processor node without writing to the second cache.

Abstract: To reduce overhead for cache coherence for shared cache in multi-processor systems, adaptive granularity allows tracking shared data at a coarse granularity and unshared data at fine granularity. Processes for adaptive granularity select how large of an entry is required to track the coherence of a block based on its state. Shared blocks are tracked in coarse-grained region entries that include a sharer tracking bit vector and a bit vector that indicates which blocks are likely to be present in the system, but do not identify the owner of the block. Modified/unshared data is tracked in fine-grained entries that permit ownership tracking and exact location and invalidation of cache. Large caches where the majority of blocks are shared and not modified create less overhead by being tracked in the less costly coarse-grained region entries.