Patent ID: 9424196
Filing Date: 2016-08-23
CPC Classification: G06F,Y02D

Claim Text:
1. A method, comprising: receiving, by a controller, a request to perform a release space operation; determining that a new discard scan has to be performed on a cache, in response to the received request to perform the release space operation; and determining how many task control blocks are to be allocated to perform the new discard scan, based on determining whether input/output (I/O) operations on the cache that cannot be performed exceed a threshold number of I/O operations, the method further comprising: in response to determining that the already allocated number of task control blocks exceed a threshold number of task control blocks, allocating only one task control block to perform the new discard scan; and in response to determining that the already allocated number of task control blocks does not exceed the threshold number of task control blocks, allocating a plurality of task control blocks to perform the new discard scan, wherein the number of task control blocks allocated for all discard scans do not exceed ten percent of a total number of task control blocks in the controller, and wherein other task control blocks are used for purposes other than discard scans, and wherein the method further comprises: allocating an anchor task control block and then allocating subscan task control blocks to perform the new discard scan, wherein the anchor task control block and each of the subscan task control blocks are executed in parallel; determining that no additional task control blocks are available to allocate to the new discard scan; and queuing the new discard scan until a task control block is made available via completion of at least one of the discard scans that are already in progress.