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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 ...
Cache in E (R) or M (D) state (exclusiveness) – The write can take place locally without any other action. The state is set (or remains) M (D) Write Miss – Write Allocate – Read with Intent to Modified operation – Like a Read miss operation plus an invalidate command, then the cache is written (updated)
The external memory model is related to the cache-oblivious model, but algorithms in the external memory model may know both the block size and the cache size. For this reason, the model is sometimes referred to as the cache-aware model. [5] The model consists of a processor with an internal memory or cache of size M, connected to an unbounded ...
Cache coherence is the discipline which ensures that the changes in the values of shared operands (data) are propagated throughout the system in a timely fashion. [2] The following are the requirements for cache coherence: [3] Write Propagation Changes to the data in any cache must be propagated to other copies (of that cache line) in the peer ...
The cache is required to write the data back to the main memory at some time in the future, before permitting any other read of the (no longer valid) main memory state. The write-back changes the line to the Shared state(S). Exclusive (E) The cache line is present only in the current cache, but is clean - it matches main memory. It may be ...
A two-level adaptive predictor remembers the history of the last n occurrences of the branch and uses one saturating counter for each of the possible 2 n history patterns. This method is illustrated in figure 3. Consider the example of n = 2. This means that the last two occurrences of the branch are stored in a two-bit shift register.
In computing, cache replacement policies (also known as cache replacement algorithms or cache algorithms) are optimizing instructions or algorithms which a computer program or hardware-maintained structure can utilize to manage a cache of information. Caching improves performance by keeping recent or often-used data items in memory locations ...
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.