Patent ID: 8468536
Filing Date: 2013-06-18
Classification: G06F

Abstract:
1. A computer-implemented method comprising: providing least recently used (LRU) selection logic which controllably pass requests for access to computer system resources to a shared resource via a first level and a second level; determining whether a request in a request group includes active blocking conditions preventing the request from being presented to the LRU selection logic; presenting the request to LRU selection logic at the first level, when it is determined based on determining that the active blocking conditions do not exist for the request; determining whether the request is a LRU request of the request group at the first level, and the request group is flagged as an LRU request group based on any active LRU request in the request group being completed; forwarding the request to the second level based on determining that the request is the LRU request of the request group; comparing the request to an LRU request from each of a plurality of request groups at the second level to determine whether the request is a LRU request of the plurality of request groups; selecting the LRU request of the plurality of request groups to access the shared resource; maintaining a value of a first latching element and a second latching element at the first and second levels respectively; determining whether the selected LRU request at the first level has finished accessing the shared resource; updating a corresponding first latching element of the LRU request at the first level by resetting the corresponding first latching element of the LRU request to mark the LRU request as a newest request based on the LRU request at the first level finishing access to the shared resource; determining whether the marked LRU request is the oldest of the request group at the first level; and updating a corresponding second latching element of the request group at the second level by resetting the corresponding second latching element of the request group to mark the request group as the newest based on the marked LRU request being the oldest of the request within the request group at the first level.