Abstract: A method and structure for an emulation system comprises of a plurality of field programmable gate arrays adapted to emulate nodes of a multi-node shared memory system, a plurality of cache directories, each connected to one of the arrays, and a plurality of global coherence directories, each connected to one of the arrays. Each of the global coherence directories maintain information on all memory lines remotely cached by each of the cache directories.

Abstract: A system and method of maintaining consistent cached copies of memory in a multiprocessor system having a main memory, includes a memory directory having entries mapping the main memory, an access history information in the memory directory entries, and a directory cache having records corresponding to a subset of the memory directory entries. The memory directory may be a full map directory having entries mapping all of the main memory or a sparse directory having entries mapping to a subset of the main memory. The method includes the steps of receiving a signal indicating a processor cache miss, retrieving a memory directory entry from the memory directory, updating the access history of the memory directory entry, selecting a directory cache line based on its access history and allocating the directory cache line for replacement, and writing the memory directory entry into the directory cache.

Abstract: A method and structure for a “dynamic CCR/sparse directory implementation,” includes maintaining state information of the main memory cached in the shared caches of the other compute nodes, organizing a cache directory so that the state information can be stored in a first area efficient CCR directory format, switching to a second sparse directory format if the entry is shared by more than one other compute node, and dynamically switching between formats so as to maximize the number of entries stored in the directory.

Abstract: A method and system for the parallel implementation of protocol engines based on memory partitioning. The method comprises the steps of partitioning a shared memory space into multiple mon-overlapping regions; and for each of the regions, using a respective one protocol engine to handle references to the region, independently of the other protocol engines. Preferably, the memory is partitioned into the non-overlapping regions either by using address interleaving or by using address range registers to identify address ranges for said regions. Also, preferably the protocol engines operate independent of each other and handle accesses to the memory regions in parallel.

Abstract: A method and structure for an emulation system comprises of a plurality of field programmable gate arrays adapted to emulate nodes of a multi-node shared memory system, a plurality of cache directories, each connected to one of the arrays, and a plurality of global coherence directories, each connected to one of the arrays. Each of the global coherence directories maintain information on all memory lines remotely cached by each of the cache directories.

Abstract: A method and structure for a “dynamic CCR/sparse directory implementation,” includes maintaining state information of the main memory cached in the shared caches of the other compute nodes, organizing a cache directory so that the state information can be stored in a first area efficient CCR directory format, switching to a second sparse directory format if the entry is shared by more than one other compute node, and dynamically switching between formats so as to maximize the number of entries stored in the directory.

Abstract: A system and method for communicating messages between nodes of a packet switched communications network, with each message having a defined message type and including message content.

Abstract: For a cache-coherent controller for a multiprocessor system sharing a cache memory, a split pending buffer having two components: a fully-associative part and an indexed part that can easily be made multi-ported. The associative part, PBA, include multiple entries having a valid bit and address fields, and the indexed part, PBC, includes entries including all the other status fields (i.e., the content part of the pending buffer entries). The split multi-ported pending buffer enables one request and one or more responses to be handled concurrently. Handling a request requires an associative lookup of PBA, a possible directory lookup, a possible read of PBC (in case of collision), and after processing the request in a request protocol handling unit, a possible PBA update, a possible PBC update, and a possible directory update, depending upon the cache coherence protocol implemented.

Abstract: A method and structure for a system for maintaining coherence of cache lines in a shared memory multiplexor system comprises a system area network and a plurality of compute nodes connected to the system area network. Each of the computer nodes includes a local main memory, a local shared cache and a local coherence controller and computer nodes external to a given compute node include external shared caches and the coherence controller includes shadow directories, each corresponding to one of the external shared caches. Each of the shadow directories includes state information of the local main memory cached in the external shared caches. The shadow directories include only state information of the local main memory cached in the external shared caches.

Abstract: A method and structure for a system for maintaining coherence of cache lines in a shared memory multiplexor system comprises a system area network and a plurality of compute nodes connected to the system area network. Each of the compute nodes includes a local main memory, a local shared cache and a local coherence controller and compute nodes external to a given compute node include external shared caches and the coherence controller includes shadow directories, each corresponding to one of the external shared caches. Each of the shadow directories includes state information of the local main memory cached in the external shared caches. The shadow directories include only state information of the local main memory cached in the external shared caches.

Abstract: A system and method of maintaining consistent cached copies of memory in a multiprocessor system having a main memory, includes a memory directory having entries mapping the main memory, an access history information in the memory directory entries, and a directory cache having records corresponding to a subset of the memory directory entries. The memory directory may be a full map directory having entries mapping all of the main memory or a sparse directory having entries mapping to a subset of the main memory. The method includes the steps of receiving a signal indicating a processor cache miss, retrieving a memory directory entry from the memory directory, updating the access history of the memory directory entry, selecting a directory cache line based on its access history and allocating the directory cache line for replacement, and writing the memory directory entry into the directory cache.