Directory-based cache coherenceIn computer engineering, directory-based cache coherence is a type of cache coherence mechanism, where directories are used to manage caches in place of bus snooping. Bus snooping methods scale poorly due to the use of broadcasting. These methods can be used to target both performance and scalability of directory systems.
Bus snoopingBus snooping or bus sniffing is a scheme by which a coherency controller (snooper) in a cache (a snoopy cache) monitors or snoops the bus transactions, and its goal is to maintain a cache coherency in distributed shared memory systems. This scheme was introduced by Ravishankar and Goodman in 1983, under the name "write-once" cache coherency. A cache containing a coherency controller (snooper) is called a snoopy cache.
Sequential consistencySequential consistency is a consistency model used in the domain of concurrent computing (e.g. in distributed shared memory, distributed transactions, etc.). It is the property that "... the result of any execution is the same as if the operations of all the processors were executed in some sequential order, and the operations of each individual processor appear in this sequence in the order specified by its program."
Locality of referenceIn computer science, locality of reference, also known as the principle of locality, is the tendency of a processor to access the same set of memory locations repetitively over a short period of time. There are two basic types of reference locality – temporal and spatial locality. Temporal locality refers to the reuse of specific data and/or resources within a relatively small time duration.MultiprocessingMultiprocessing (MP) is the use of two or more central processing units (CPUs) within one computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them.
Cache (computing)In computing, a cache ( ) is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot.
Central processing unitCentral computer component that executes instructionsCore i9-14900KF, a 2023 CPU made by IntelInside a central processing unit: The integrated circuit of Intel's Xeon 3060, first manufactured in 2006A central processing unit (CPU), also known as a central processor, main processor, or simply processor, is the primary processor in a given computer.
GranularityGranularity (also called graininess) is the degree to which a material or system is composed of distinguishable pieces, "granules" or "grains" (metaphorically). It can either refer to the extent to which a larger entity is subdivided, or the extent to which groups of smaller indistinguishable entities have joined together to become larger distinguishable entities.
Computer architectureIn computer science and computer engineering, a computer architecture is the conceptual design and operational structure of a computer system that define how component parts are organized and interact to execute programs efficiently. It is often a general description that ignores precise implementation details. It covers the instruction set architecture, CPU microarchitecture, memory, and input/output systems.List of cache coherency protocolsExamples of coherency protocols for cache memory are listed here. For simplicity, all "miss" Read and Write status transactions, which all only come from state "I" ("invalid", or miss of Tag), in the diagrams are not shown. They are shown directly on the new state. Many of the following protocols have only historical value. At the moment the main protocols used are the R-MESI type / MESIF protocols and the HRT-ST-MESI (MOESI type) or a subset or an extension of these.Shared-memory architectureA shared-memory architecture (SM) is a distributed computing architecture in which the nodes share the same memory as well as the same storage. It contrasts with shared-nothing architecture, in which each node has distinct memory and storage, and with shared-disk architecture, in which the nodes share the same storage but not the same memory. This is distinct from the use of shared memory between different programs or threads on a single node, with or without multiprocessing.*As an Amazon Associate I earn from qualifying purchases.