Thrash (computer science)
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In computer science, thrash is the poor performance of a virtual memory (or paging) system, when the same pages are being loaded repeatedly due to a lack of main memory to keep them in memory. Depending on the configuration and algorithm, the real throughput of a system can degrade by multiple orders of magnitude.
In software testing, thrashing means to extensively test a software system, giving a program various inputs and observing the behavior and outputs that result.
In computer science (or computer architecture in particular), thrashing refers to the poor performance of cache memory (caching) or virtual memory (paging), constantly swapping data in and out without performing useful work. Thrashing arises from that programs or workloads present little or insufficient locality of reference for caching or paging to work. Put another way, if the working set of a program or a workload cannot be effectively held within the cache or the main memory, then constant yet useless data swapping, i.e., thrashing, will occur. Originally thrashing describes the phenomenon that data are constantly being swapped between main memory and hard disk, thus making sounds due to continuous disk heads moving.
Reference
- M. Morris Mano and Charles R. Kim, "Logic and Computer Design Fundamentals", pp. 622.