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Unlike the RAM machine model, it also introduces a cache: the second level of storage between the RAM and the CPU. The other differences between the two models are listed below. In the cache-oblivious model: The cache on the left holds blocks of size each, for a total of M objects. The external memory on the right is unbounded.
Each upper-level cache component is a subset of the lower-level cache component. In this case, since there is a duplication of blocks, there is some wastage of memory. However, checking is faster. [citation needed] Under an exclusive policy, all the cache hierarchy components are completely exclusive, so that any element in the upper-level ...
Sending cache is changed in S and the requesting cache is set R/F (in read miss the "ownership" is always taken by the last requesting cache) – shared intervention. – In all the other cases the data is supplied by the memory and the requesting cache is set S (V). Data stored in MM and only in one cache in E (R) state.
A cache has two primary figures of merit: latency and hit ratio. A number of secondary factors also affect cache performance. [1] The hit ratio of a cache describes how often a searched-for item is found. More efficient replacement policies track more usage information to improve the hit rate for a given cache size.
If all blocks in the higher level cache are also present in the lower level cache, then the lower level cache is said to be inclusive of the higher level cache. If the lower level cache contains only blocks that are not present in the higher level cache, then the lower level cache is said to be exclusive of the higher level cache. If the ...
The original form of the pattern, appearing in Pattern Languages of Program Design 3, [2] has data races, depending on the memory model in use, and it is hard to get right. Some consider it to be an anti-pattern. [3] There are valid forms of the pattern, including the use of the volatile keyword in Java and explicit memory barriers in C++. [4]
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A hash-rehash cache and a column-associative cache are examples of a pseudo-associative cache. In the common case of finding a hit in the first way tested, a pseudo-associative cache is as fast as a direct-mapped cache, but it has a much lower conflict miss rate than a direct-mapped cache, closer to the miss rate of a fully associative cache.