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Efficiency of memory hierarchy use: Although random-access memory presents the programmer with the ability to read or write anywhere at any time, in practice latency and throughput are affected by the efficiency of the cache, which is improved by increasing the locality of reference. Poor locality of reference results in cache thrashing and ...
In computing, a memory access pattern or IO access pattern is the pattern with which a system or program reads and writes memory on secondary storage.These patterns differ in the level of locality of reference and drastically affect cache performance, [1] and also have implications for the approach to parallelism [2] [3] and distribution of workload in shared memory systems. [4]
LIRS (Low Inter-reference Recency Set) is a page replacement algorithm with an improved performance over LRU (Least Recently Used) and many other newer replacement algorithms. [1] This is achieved by using "reuse distance" [ 2 ] as the locality metric for dynamically ranking accessed pages to make a replacement decision.
Most modern CPUs are so fast that for most program workloads, the bottleneck is the locality of reference of memory accesses and the efficiency of the caching and memory transfer between different levels of the hierarchy [citation needed]. As a result, the CPU spends much of its time idling, waiting for memory I/O to complete.
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 ...
This is primarily due to CPU caching which exploits spatial locality of reference. [1] In addition, contiguous access makes it possible to use SIMD instructions that operate on vectors of data. In some media such as magnetic-tape data storage , accessing sequentially is orders of magnitude faster than nonsequential access.
Set-associative cache is a trade-off between direct-mapped cache and fully associative cache. A set-associative cache can be imagined as a n × m matrix. The cache is divided into ‘n’ sets and each set contains ‘m’ cache lines. A memory block is first mapped onto a set and then placed into any cache line of the set.
It could be worse: IBM System/360 mainframes only have an unsigned 12-bit offset. However, the principle of locality of reference applies: over a short time span, most of the data items a program wants to access are fairly close to each other. This addressing mode is closely related to the indexed absolute addressing mode.