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Date: Thu, 11 Apr 2013 10:02:32 +0200
From: Stefan Hajnoczi <stefanha@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2] rbd: add an asynchronous flush
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To: Josh Durgin <josh.durgin@inktank.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org

On Wed, Apr 10, 2013 at 07:03:39AM -0700, Josh Durgin wrote:
> On 04/02/2013 07:10 AM, Kevin Wolf wrote:
> >Am 29.03.2013 um 21:03 hat Josh Durgin geschrieben:
> >>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.
> >
> >librbd is linked dynamically and the version on the build host isn't
> >necessarily the same as the version qemu is run with. So shouldn't this
> >better be a runtime check?
> 
> While we discuss runtime loading separately, would you mind taking this
> patch as-is for now?

Hi Josh,
I'm happy with Patch v3 1/2.  Does that work for you?

I don't want to take Patch v3 2/2 or the dlsym() function pointer patch.

Stefan