Systematic recovery of excessive spin loops in an n-way mp environment.

摘要

A program executing on a first processor in an MP configuration awaiting the release of a resource held by another processor, detects the expiration of a fixed time interval, and initiates a hierarchy of recovery actions designed to cause the resource to be freed. These actions, targeted at a processor believed to be the one currently holding the resource, are taken only if that processor is not executing an "exempt" routine. The actions, taken in order of increasing severity, are: wait for a second fixed time interval; terminate the routine on the resource-holding processor, allowing retry; terminate the routine without allowing retry; invoke Alternate CP Recovery. The hierarchy is escalated against the target processor until that processor releases the resource, and against other processors in the configuration until the resource is acquired by the first processor. These actions may proceed in parallel for multiple detecting and target processors within an MP environment.