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Variable timeout method in a missing-interrupt-handler for I/O requests issued by the same operating system

  • US 5,768,620 A
  • Filed: 04/09/1996
  • Issued: 06/16/1998
  • Est. Priority Date: 04/09/1996
  • Status: Expired due to Fees
First Claim
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1. A method of avoiding false detection of missing I/O interrupt signals by an operating system (OS) for use in a computer arrangement having at least one OS and a missing interrupt handler (MIH) process for detecting a potentially failed input/output (I/O) device operation for an I/O request issued by the OS to an I/O subsystem, the MIH process comprising the steps of:

  • sending by the OS to the I/O subsystem a first I/O request and a second I/O request, the first I/O request associated with a first I/O program containing at least one command for controlling an I/O device, the second I/O request associated with a second I/O program containing at least one command for controlling the I/O device,operating the I/O device under control of the first I/O program for the first I/O request, delaying operation of the second I/O request in the I/O subsystem because of the I/O device currently operating for the first I/O request,measuring MIH time for a primary MIH timeout period starting when the second I/O request is made to wait by the I/O subsystem,signalling a device-completion interrupt to the OS when and if the I/O device successfully completes operation for the first I/O request,terminating the measurement step if the device-completion interrupt for the first I/O request is received by the OS before measuring the end of the primary MIH timeout period,but scanning the first I/O program for a long command requiring the I/O device to operate for an excessive amount of time if no device-end interrupt is received by the OS before measuring the end of the primary MIH timeout period,continuing measuring the MIH time for a secondary MIH timeout period if the scanning step finds the long command in the first I/O program, andterminating the continuing measuring step if the device-completion interrupt for the first I/O request is received by the OS before the measuring step indicates the end of the secondary MIH timeout period.

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