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This cache was termed Level 1 or L1 cache to differentiate it from the slower on-motherboard, or Level 2 (L2) cache. These on-motherboard caches were much larger, with the most common size being 256 KiB. There were some system boards that contained sockets for the Intel 485Turbocache daughtercard which had either 64 or 128 Kbyte of cache memory.
However, with a multiple-level cache, if the computer misses the cache closest to the processor (level-one cache or L1) it will then search through the next-closest level(s) of cache and go to main memory only if these methods fail. The general trend is to keep the L1 cache small and at a distance of 1–2 CPU clock cycles from the processor ...
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 ...
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 ...
Since each cache block is of size 4 bytes and is 2-way set-associative, the total number of sets in the cache is 256/(4 * 2), which equals 32 sets. Set-Associative Cache. The incoming address to the cache is divided into bits for Offset, Index and Tag. Offset corresponds to the bits used to determine the byte to be accessed from the cache line.
Level 2 (L2) Instruction and data (shared) – 1 MiB [citation needed] [original research] in size. Best access speed is around 200 GB/s [9] Level 3 (L3) Shared cache – 6 MiB [citation needed] [original research] in size. Best access speed is around 100 GB/s [9] Level 4 (L4) Shared cache – 128 MiB [citation needed] [original research] in size.
Unsuccessful attempts to read or write data from the cache (cache misses) result in lower level or main memory access, which increases latency. There are three basic types of cache misses known as the 3Cs [2] and some other less popular cache misses.
Though initially proposed by Jouppi to improve cache performance of a direct-mapped cache Level 1, modern day microprocessors with multi-level cache hierarchy employ Level 3 or Level 4 cache to act as victim cache for the cache lying above it in the memory hierarchy. Intel's Crystal Well [2] of its Haswell processors introduced an on-package ...