From: Kevin Wolf <kwolf@redhat.com>
To: Josh Durgin <josh.durgin@inktank.com>
Cc: qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2] rbd: add an asynchronous flush
Date: Tue, 2 Apr 2013 16:10:42 +0200 [thread overview]
Message-ID: <20130402141042.GL2341@dhcp-200-207.str.redhat.com> (raw)
In-Reply-To: <1364587403-30689-1-git-send-email-josh.durgin@inktank.com>
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?
> 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>
Looks good otherwise.
Kevin
next prev parent reply other threads:[~2013-04-02 14:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-29 7:59 [Qemu-devel] [PATCH] rbd: add an asynchronous flush Josh Durgin
2013-03-29 20:03 ` [Qemu-devel] [PATCH v2] " Josh Durgin
2013-04-02 14:10 ` Kevin Wolf [this message]
2013-04-04 8:35 ` [Qemu-devel] [PATCH v3 1/2] " Josh Durgin
2013-04-04 8:35 ` [Qemu-devel] [PATCH 2/2] rbd: disable unsupported librbd functions at runtime Josh Durgin
2013-04-04 10:10 ` Kevin Wolf
2013-04-04 16:50 ` Josh Durgin
2013-04-05 9:31 ` Kevin Wolf
2013-04-10 0:05 ` [Qemu-devel] [PATCH v3 2/2] rbd: link and load librbd dynamically Josh Durgin
2013-04-10 8:09 ` Stefan Hajnoczi
2013-04-10 14:52 ` [Qemu-devel] runtime Block driver modules (was Re: [PATCH v3 2/2] rbd: link and load librbd dynamically) Josh Durgin
2013-04-10 15:08 ` [Qemu-devel] [PATCH v3 2/2] rbd: link and load librbd dynamically Anthony Liguori
2013-04-10 21:19 ` Paolo Bonzini
2013-04-11 8:04 ` Stefan Hajnoczi
2013-04-11 7:59 ` Stefan Hajnoczi
2013-06-21 18:42 ` Sage Weil
2013-06-21 19:08 ` Alex Bligh
2013-06-21 19:13 ` Anthony Liguori
2013-04-10 14:03 ` [Qemu-devel] [PATCH v2] rbd: add an asynchronous flush Josh Durgin
2013-04-11 8:02 ` Stefan Hajnoczi
2013-04-11 8:48 ` Kevin Wolf
2013-04-11 17:19 ` Josh Durgin
2013-04-12 6:50 ` Kevin Wolf
2013-04-12 7:42 ` Stefan Hajnoczi
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