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EFFICIENT HANDLING OF QUEUED-DIRECT I/O REQUESTS AND COMPLETIONS

  • US 20110106990A1
  • Filed: 10/30/2009
  • Published: 05/05/2011
  • Est. Priority Date: 10/30/2009
  • Status: Active Grant
First Claim
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1. A computer program product for handling of queued-direct input/output (QDIO) requests at an adapter in communication with an I/O device, the computer program product comprising:

  • a storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for implementing a method, the method comprising;

    accessing a queue comprising one or more storage block address lists (SBALs), each SBAL comprised of a plurality of storage block address list entries (SBALEs) and associated with a storage list status block (SLSB);

    reading an SBAL count in one of the SBALEs, the SBAL count indicating a number of the SBALs forming an I/O request to the I/O device; and

    in response to determining that the SBAL count is greater than one, prefetching a number of the SBALs from the queue and associated SLSBs equivalent to the SBAL count without waiting for a notification of completion of each of the SBALs forming the I/O request, and transitioning states of the associated SLSBs from adapter-owned to program-owned.

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