Re: [Qemu-devel] [Qemu-stable] Patch Round-up for stable 1.4.2, freeze on Monday

[mdroth <mdroth@linux.vnet.ibm.com>]

On Fri, May 17, 2013 at 01:43:28PM -0700, Josh Durgin wrote:
> On 05/17/2013 12:08 PM, mdroth wrote:
> >On Fri, May 17, 2013 at 10:46:15AM -0500, Doug Goldstein wrote:
> >>On Tue, May 14, 2013 at 4:52 PM, Michael Roth <mdroth@linux.vnet.ibm.com>wrote:
> >>
> >>>Hi everyone,
> >>>
> >>>The following new patches are queued for QEMU stable v1.4.2:
> >>>
> >>>https://github.com/mdroth/qemu/commits/stable-1.4-staging
> >>>
> >>>The release is planned for 05-24-2013:
> >>>
> >>>http://wiki.qemu.org/Planning/1.4
> >>>
> >>>Please CC qemu-stable@nongnu.org on any patches you think should be
> >>>included in the release. The cut-off date is 05-20-2013 for new patches.
> >>>
> >>>Testing/feedback is greatly appreciated.
> >>>
> >>>Thanks!
> >>>
> >>>
> >>Michael,
> >>
> >>I have one patch in my 1.4 stable queue.
> >>
> >>From: Paolo Bonzini <pbonzini@redhat.com>
> >>Date: Wed, 13 Mar 2013 14:58:13 +0000 (+0100)
> >>Subject: qemu-iotests: add tests for rebasing zero clusters
> >>X-Git-Url: http://git.qemu.org/?p=qemu.git;a=commitdiff_plain;h=acbf30ec601b1f817febc4500025b7c4181312c4
> >>
> >>qemu-iotests: add tests for rebasing zero clusters
> >>
> >>If zero clusters are erroneously treated as unallocated, "qemu-img rebase"
> >>will copy the backing file's contents onto the cluster.
> >>
> >>The bug existed also in image streaming, but since the root cause was in
> >>qcow2's is_allocated implementation it is enough to test it with qemu-img.
> >>
> >>Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >>Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> >>
> >>---
> >>
> >>
> >>It only adds a test for something that was fixed in 1.4.1 (maybe was fixed
> >>by the final 1.4.0 release I can't recall).
> >
> >Thanks, pushed this to staging along with what should be all outstanding
> >patches noted so far.
> 
> Could you add the patch:
> 
> commit dc7588c1eb3008bda53dde1d6b890cd299758155
> Author: Josh Durgin <josh.durgin@inktank.com>
> Date:   Fri Mar 29 13:03:23 2013 -0700
> 
> rbd: add an asynchronous flush
> 
> The existing bdrv_co_flush_to_disk implementation uses rbd_flush(),
> which is sychronous and causes the main qemu thread to block until it
> is complete. This results in unresponsiveness and extra latency for
> the guest.
> 
> Fix this by using an asynchronous version of flush.  This was added to
> librbd with a special #define to indicate its presence, since it will
> be backported to stable versions. Thus, there is no need to check the
> version of librbd.
> 
> Implement this as bdrv_aio_flush, since it matches other aio functions
> in the rbd block driver, and leave out bdrv_co_flush_to_disk when the
> asynchronous version is available.
> 
> Reported-by: Oliver Francke <oliver@filoo.de>
> Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> 
> I sent a cherry-pick of it to qemu-stable a couple days ago, although
> it applies to the stable-1.4 branch cleanly. It fixes a significant
> interactivity and performance problem when rbd is used with caching
> enabled.

Hmm, not sure how that slipped by me. Just applied it to staging tree:

https://github.com/mdroth/qemu/commits/stable-1.4-staging

> 
> Thanks,
> Josh
>