Search results
Results From The WOW.Com Content Network
While all of the cache blocks in a particular cache are the same size and have the same associativity, typically the "lower-level" caches (called Level 1 cache) have a smaller number of blocks, smaller block size, and fewer blocks in a set, but have very short access times.
The block occupies a cache line in set 31, determined by the replacement policy for the cache. Address 0x0100 (tag – 0b000_0010, index – 0b0_0000, offset – 0b00) corresponds to block 64 of the memory and maps to the set 0 of the cache. The block occupies a cache line in set 0, determined by the replacement policy for the cache.
Cache hits are the number of accesses to the cache that actually find that data in the cache, and cache misses are those accesses that don't find the block in the cache. These cache hits and misses contribute to the term average access time (AAT) also known as AMAT ( average memory access time ), which, as the name suggests, is the average time ...
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.
A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests that can be served from the cache, the faster the system performs.
Consider the case when L2 is inclusive of L1. Suppose there is a processor read request for block X. If the block is found in L1 cache, then the data is read from L1 cache and returned to the processor. If the block is not found in the L1 cache, but present in the L2 cache, then the cache block is fetched from the L2 cache and placed in L1.
It is different than the external memory model because cache-oblivious algorithms do not know the block size or the cache size. In particular, the cache-oblivious model is an abstract machine (i.e., a theoretical model of computation). It is similar to the RAM machine model which replaces the Turing machine's infinite tape with an infinite array.
Hence most of the entries in the directory will belong to uncached blocks. In the sparse directory format the wastage is reduced by storing only the cached blocks in the directory. [citation needed] Consider a processor with a cache size of 64KB with a block size of 32 bytes and the main memory size to be 4MB. The maximum number of entries that ...