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Variable timeout method for improving missing-interrupt-handler operations in an environment having I/O devices shared by one or more systems

  • US 5,894,583 A
  • Filed: 04/09/1996
  • Issued: 04/13/1999
  • Est. Priority Date: 04/09/1996
  • Status: Expired due to Fees
First Claim
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1. A method for use in a computer arrangement having a plurality of operating systems (OSs) in which each OS has a missing interrupt handler (MIH) process for detecting a failed input/output (I/O) device operation for an I/O request issued by the OS to an I/O subsystem, the OSs sharing at least one I/O controller connected to I/O devices, the MIH process comprising the steps of;

  • storing a plurality of MIH timeout extension values in the computer arrangement accessible to the MIH process including a primary timeout value and a secondary timeout value,storing at least one CU threshold timeout value accessible to the CU,sending an I/O request from the OS to the CU for an operation by an I/O device connected to the CU, and rejecting the I/O request by the CU if the I/O device is not then available for use by the I/O request,starting a MIH timer process from a zero time value and using the primary timeout value as a current MIH timeout value for the I/O request when the I/O request is sent to the CU, and signalling an MIH timeout when and if the MIH timer process reaches a time equal to or greater than the current MIH timeout value,contending by the I/O request with any other concurrent I/O requests in the CU for use of the I/O device,initiating an CU threshold timer process from a zero time value to measure CU threshold elapsed time for the I/O request if the I/O request is rejected by the CU when the I/O device is busy,indicating a CU threshold timeout if elapsed time measured by the CU threshold timer process is equal to or greater than the CU threshold timeout value,CU signalling a long-busy interrupt to the OS when and if the CU threshold timer process indicates the CU threshold timeout,replacing the current MIH timeout value with the MIH secondary timeout value for an OS timer process in response to the CU signalling of the long-busy interrupt, andsignalling the MIH timeout when and if the MIH timer process reaches an elapsed time equal to or greater than the MIH secondary timeout value to indicate the I/O device operation has failed.

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