Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [PATCH v3.4-rc5] block: iocontext->nr_tasks should be initialized to one | Date | Tue, 01 May 2012 15:04:49 -0400 |
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Vivek Goyal <vgoyal@redhat.com> writes:
> On Tue, May 01, 2012 at 02:48:41PM -0400, Jeff Moyer wrote: >> Vivek Goyal <vgoyal@redhat.com> 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.
Cheers, Jeff
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