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Cache placement policies are policies that determine where a particular memory block can be placed when it goes into a CPU cache. A block of memory cannot necessarily be placed at an arbitrary location in the cache; it may be restricted to a particular cache line or a set of cache lines [1] by the cache's placement policy. [2] [3]
The RRIP backend makes the eviction decisions. The sampled cache and OPT generator set the initial RRPV value of the inserted cache lines. Hawkeye won the CRC2 cache championship in 2017, [24] and Harmony [25] is an extension of Hawkeye which improves prefetching performance. Block diagram of the Mockingjay cache replacement policy
The placement policy decides where in the cache a copy of a particular entry of main memory will go. If the placement policy is free to choose any entry in the cache to hold the copy, the cache is called fully associative. At the other extreme, if each entry in the main memory can go in just one place in the cache, the cache is direct-mapped.
The merit of inclusive policy is that, in parallel systems with per-processor private cache if there is a cache miss other peer caches are checked for the block. If the lower level cache is inclusive of the higher level cache and it is a miss in the lower level cache, then the higher level cache need not be searched.
Consider the following illustration: T[0] = T[0] + 1; for i in 0..sizeof(CACHE) C[i] = C[i] + 1; T[0] = T[0] + C[sizeof(CACHE)-1]; (The assumptions here are that the cache is composed of only one level, it is unlocked, the replacement policy is pseudo-LRU, all data is cacheable, the set associativity of the cache is N (where N > 1), and at most one processor register is available to contain ...
When the CPU cache was moved inside the CPU, the CPUs implemented fixed-range MTRRs which cover the first megabyte of memory to be compatible to what PC-BIOSes provided at that time. These are used to control the cache policy needed for VGA accesses and all other memory-accesses done while the system is in real mode.
Diagram of a CPU memory cache operation. In computing, a cache (/ k æ ʃ / ⓘ KASH) [1] is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere.
[e] Writes back all modified cache lines in the processor's internal cache to main memory and invalidates the internal caches. ^ Using BSWAP with 16-bit registers is not disallowed per se (it will execute without producing an #UD or other exceptions) but is documented to produce undefined results – it is reported to produce various different ...