Variable timeout method in a missing-interrupt-handler for i/o requests

Abstract

Missing interrupt handler (MIH) internal software features support a variable MIH timeout for I/O requests issued by an operating system (OS), when the same OS is involved with both an executing I/O request and a waiting I/O request. The OS varies its MIH timeout period without a signal from any I/O entity to prevent a false indication of a potential failure in a current I/O device operation. If a current I/O request has not completed when the OS senses the end of a primary MIH timeout period, started when issuing that request, the OS then scans the I/O program of that I/O request for any contained long-running command. (Most I/O requests complete during their primary MIH timeout period.) If a long command is found, the OS extends the MIH timeout period from the primary MIH timeout period to a long MIH timeout period, The latter gives the I/O device more time to complete its operation before the OS indicates it has a potential I/O error condition. But if the OS does not detect any long-running command in its scan of the I/O program, the OS does not extend the primary MIH timeout period, and then the OS declares a potential I/O error condition for the current I/O device operation and invokes a conventional I/O error recovery program, such as retrying that I/O request for a number of times until it runs without error or until a permanent error condition is determined.