What Is Cache Coherence?

Keeping your data consistent across the board and safe at the very same time is critical when sharing a computer. Ensure that the right people access the correct information on your network by maintaining cache coherency with a coherence protocol. Cache coherency is a measure of the consistency and predictability of the contents of a cache. It measures the reliability of a single computer's memory system. When dealing with distributed shared memory (DSM) in multiprocessor systems, maintaining cache coherency is one of the essential factors. The DSM system maintains cache coherence by monitoring what data is written to shared memory. When a process writes data to shared memory, the DSM system copies it to its private cache. The DSM system then initiates a coherency protocol, such as a write-invalidate protocol, to invalidate other supplies that may have a copy of the data stored there. This process is often referred to as "publishing" the data. Once the data has been published, the DSM system initiates a write-read protocol to publish the data to the other caches. The caches in shared-memory multiprocessors utilize a cache coherence management scheme. It allows the system to maintain a coherent memory view, providing consistent values through shared memory. These protocols use specific methods to ensure that data is cached in more than one location and updated in other areas as they are changed. The most common form today is sequential consistency, where each operation must complete before being executed again. Other systems can use weak or release consistency standards instead. There are several levels of cache coherence that manufacturers can implement. The story of coherence required by an application will determine which cache coherence method is necessary. The amount of cache coherence required also affects the performance of a system due to the overhead associated with maintaining coherence.