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    SubjectRe: [PATCH v3.4-rc5] block: iocontext->nr_tasks should be initialized to one
    Vivek Goyal <> writes:

    > On Tue, May 01, 2012 at 02:48:41PM -0400, Jeff Moyer wrote:
    >> Vivek Goyal <> writes:
    >> > On Tue, May 01, 2012 at 02:31:07PM -0400, Jeff Moyer wrote:
    >> >
    >> > [..]
    >> >> > But as to actual users, I really don't know. I agree it's probably not
    >> >> > that widely used. If google still had that code search, we could get a
    >> >> > better idea :-)
    >> >>
    >> >> I know of one project: the venerable dump/restore utility uses CLONE_IO.
    >> >
    >> > I thought you wrote cooperating queue logic to fix dump as it was not
    >> > using CLONE_IO and IO from multiple threads was going in separate
    >> > queues.
    >> That's correct. I believe I sent the patch for dump before the kernel
    >> patch was accepted. Plus, it can't hurt, right?
    > Ok, so now you have fixed dump to use CLONE_IO.
    > So only other user of coop thing remaining potentially is qemu. I was

    No, that's not the *only* other potential user. ;-) I wouldn't be
    surprised if nfsd benefitted from the merging. I also wouldn't be
    surprised if other 3rd party apps did. Are you trying to make a case to
    get rid of the queue merging logic?

    > doing some qemu testing where threads were doing IO to nearby area
    > but no coop merging was taking place. So not sure in practice how well
    > does it work.

    Well, that sounds like it warrants further investigation.

    > Thought, that's irrlevant for this discussion. Thought of mentioning
    > this observation.

    If you can provide a reproducer, I'll be happy to take a look.


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