Hello,

Is there any way of prioritizing / reordering / rescheduling disk requests
in Windows, maybe via a file system or disk filter driver?

The idea would be to effectively shuffle them around according to their
importance. This importance could, for example, be determined according to
the PID which generated the original request (assuming the PID is
determinable).
In addition to some kind of "shuffle", maybe some functionality could be
included that would examine the PID that originated a disk request and
accordingly either send it on for processing immediately, and hold it in a
"pending" queue.

In the same way that processes can be prioritised so that certain tasks take
precedence over others, I'd like to provide similar kind of functionality for
disk requests.

Having done some research into this topic, I haven't yet found anything
about whether this is possible in Windows (although it seems possible in
Linux - and this product seems to do the kind of thing I'd like to do in
Windows: http://db.cwi.nl/rapporten/abstract.php?abstractnr=610), so I
thought I would ask the question.

Thanks in advance for any advice or pointers that may help,
JP

Go to the OSR lists, this was discussed in the last few months there.
Basically, every approach to this decreases performance of Windows
significantly.


--
Don Burn (MVP, Windows DDK)
Windows 2k/XP/2k3 Filesystem and Driver Consulting
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"J Prendergast" <j.prendergast@nospam.nospam> wrote in message
news95AF49F-5ED7-483A-8504-6ACE795836F0@microsoft.com...

Don Burn wrote:
the lower level of the storage stack (disk.sys and below) are dealing
entirely with anonymous blobs of SRBs that are prioritized based on
efficiency of delivery to/from the physical media and nothing else. A
priority scheme based on PID would be an upper level storage stack
concept - filesystem level. Note also that process id and disk IO are
generally not related in any way once the original request has entered
the filesystem.

--

=====================
Mark Roddy DDK MVP
Windows 2003/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com