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When FAST I/O Used? RRS feed

Answers

  • FAST_IO is rarely used except for file system drivers.  If the initial driver in a stack does not support FAST_IO and IRP is always called.  If FAST_IO is supported then it can indicate whether it can complete an operation (which it must do without pending the operation) or not, if not an IRP is called.

    Basically, if a driver supports FAST_IO for a given operation and decides it can synchronously complete it then FAST_IO occurs, otherwise the IO manager creates an IRP to do the operation.


    Don Burn Windows Driver Consulting Website: http://www.windrvr.com

    • Marked as answer by Thomas Hopes Thursday, January 21, 2016 2:18 AM
    Thursday, January 21, 2016 1:59 AM

All replies

  • FAST_IO is rarely used except for file system drivers.  If the initial driver in a stack does not support FAST_IO and IRP is always called.  If FAST_IO is supported then it can indicate whether it can complete an operation (which it must do without pending the operation) or not, if not an IRP is called.

    Basically, if a driver supports FAST_IO for a given operation and decides it can synchronously complete it then FAST_IO occurs, otherwise the IO manager creates an IRP to do the operation.


    Don Burn Windows Driver Consulting Website: http://www.windrvr.com

    • Marked as answer by Thomas Hopes Thursday, January 21, 2016 2:18 AM
    Thursday, January 21, 2016 1:59 AM
  • Would  you mind to Answer l  this question as well?
    Thursday, January 21, 2016 2:17 AM