Re: [Qemu-devel] Re: [PATCH] ceph/rbd block driver for qemu-kvm (v3)

[Christian Brunner]

On Tue, Jul 13, 2010 at 11:27:03AM -0700, Yehuda Sadeh Weinraub wrote:
> >
> > There is another problem with very large i/o requests. I suspect that
> > this can be triggered only
> > with qemu-io and not in kvm, but I'll try to get a proper solution it 
> > anyway.
> >
> 
> Have you made any progress with this issue? Just note that there were
> a few changes we introduced recently (a format change that allows
> renaming of rbd images, and some snapshots support), so everything
> will needed to be reposted once we figure out the aio issue.

Attached is a patch where I'm trying to solve the issue
with pthreads locking. It works well with qemu-io, but I'm
not sure if there are interferences with other threads in
qemu/kvm (I didn't have time to test this, yet).

Another thing I'm not sure about is the fact, that these
large I/O requests only happen with qemu-io. I've never seen
this happen inside a virtual machine. So do we really have
to fix this, as it is only a warning message (laggy).

Regards,

Christian

0027-add-queueing-delay-based-on-queuesize.patch
Description: Text document