Selectively retaining a topmost subpool expansion to prevent thrashing

A method for improving subpool performance comprising:

• queuing an expansion to a memory subpool on top of the subpool when a subpool expansion size is tuned to a maximum size;
• retaining the expansion queued on top of the subpool while the subpool expansion size is tuned to the maximum size;
• and
• wherein the retaining step retains only one expansion, the one on to the subpool, while other subpool expansions are released when storage is no longer immediately needed by the associated processes for which the expansion was established.

A computer program product improving subpool performance, the computer program product comprising:

• a non-transitory computer usable medium having computer usable program code embodied therewith, the computer usable program code comprising:
• computer usable program code configured to determine an appropriate subpool expansion size needed to satisfy storage requests by processes able to utilize a subpool of memory;
• computer usable program code configured to dynamically repeat the determining of the appropriate subpool expansion size as storage requirements change;
• computer usable program code configured to selectively add an expansion to the subpool to satisfy storage requests when additional storage is needed;
• computer usable program code configured to queue the added expansion on top of the subpool when a value of the subpool expansion size is a maximum size at a time that the added expansion is to be queued;
• computer usable program code configured to queue the added expansion on bottom of the subpool when the value of the subpool expansion size less than the maximum size at a time that the added expansion is to be queued;
• computer usable program code configured to determine that processes utilizing the queued expansion of the subpool have completed processing so that the queued expansion is no longer immediately necessary for storage of values relating to currently executing processes;
• computer usable program code configured to retain only one expansion queued on top of the subpool and when the value of the subpool expansion size is the maximum size at a time the currently executing processes utilizing the queued expansion have completed processing;
• and
• computer usable program code configured to release the queued expansion when the queued expansion is not on top of the subpool and when the queued expansion is on top of the subpool and when the value of the subpool expansion size is less than the maximum size at the time the currently executing processes utilizing the queued expansion have completed processing.