FastIoDispatch and File System Filters

Discussion in 'Windows Vista Drivers' started by Subodh Radheshyam Gupta, Dec 16, 2004.

  1. When a File System Filter Driver Does not have Fast io Routiens in that case
    what will happens of these 2s -

    1- Io Manager will generate and IRP and send it to Filter anyways.
    or
    2- Io manager will bypass the filter and call lower /lowest drivers Fast Io
    Routines when a FastIo requst is initialted ?That means filter wont be able
    to see the Fast IO Requests generated.

    Subodh
     
    Subodh Radheshyam Gupta, Dec 16, 2004
    #1
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  2. Subodh Radheshyam Gupta

    Mark Roddy Guest

    FastIo does not bypass the original target driver. Either it is
    transformed into an equivalent IRP request or it fails.

    --

    =====================
    Mark Roddy DDK MVP
    Windows 2003/XP/2000 Consulting
    Hollis Technology Solutions 603-321-1032
     
    Mark Roddy, Dec 16, 2004
    #2
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  3. Hi mark,
    Thanks..So in case if filter does not have implemented FastIo
    Routines.,,.and underlying FS supports it..that means loss of performance..Is
    there any way to measure the loss ?
    Regards
    Subodh
     
    Subodh Radheshyam Gupta, Dec 17, 2004
    #3
  4. Subodh Radheshyam Gupta

    Mark Roddy Guest


    Sure: run performance test without filter driver. Run performance test
    with filter driver. Compare.

    I believe that filesystem filter drivers generally require some of the
    fastio interfaces for correct behavior. You should get the IFS kit from
    microsoft and study the samples there for a better understanding of how
    this all works.


    --

    =====================
    Mark Roddy DDK MVP
    Windows 2003/XP/2000 Consulting
    Hollis Technology Solutions 603-321-1032
     
    Mark Roddy, Dec 17, 2004
    #4
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