Search results
Results from the WOW.Com Content Network
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. [1] A cache is a smaller, faster memory, located closer to a processor core, which stores copies of the data from frequently used main memory locations.
The placement determines whether the cache uses physical or virtual addressing. If the cache is virtually addressed, requests are sent directly from the CPU to the cache, and the TLB is accessed only on a cache miss. If the cache is physically addressed, the CPU does a TLB lookup on every memory operation, and the resulting physical address is ...
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.
Where the translation lookaside buffer (TLB) acting as a cache for the memory management unit (MMU) which translates virtual addresses to physical addresses is too small for the working set of pages. TLB thrashing can occur even if instruction cache or data cache thrashing is not occurring because these are cached in different sizes.
Virtual memory combines active RAM and inactive memory on DASD [a] to form a large range of contiguous addresses.. In computing, virtual memory, or virtual storage, [b] is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" [3] which "creates the illusion to users of a very large (main) memory".
Illustration of cache coloring. Left is virtual memory spaces, center is the physical memory space, and right is the CPU cache.. A physically indexed CPU cache is designed such that addresses in adjacent physical memory blocks take different positions ("cache lines") in the cache, but this is not the case when it comes to virtual memory; when virtually adjacent but not physically adjacent ...
If a process has recently run on one virtual hyper-threaded CPU in a given core, and that virtual CPU is currently busy but its partner CPU is not, cache affinity would suggest that the process should be dispatched to the idle partner CPU. However, the two virtual CPUs compete for essentially all computing, cache, and memory resources.
The memory management unit (MMU) inside the CPU stores a cache of recently used mappings from the operating system's page table. This is called the translation lookaside buffer (TLB), which is an associative cache. When a virtual address needs to be translated into a physical address, the TLB is searched first.