From: Kevin Wolf <kwolf@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: ming.lei@canonical.com, pl@kamp.de, qemu-devel@nongnu.org,
stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted
Date: Tue, 16 Dec 2014 12:07:27 +0100 [thread overview]
Message-ID: <20141216110727.GA27195@noname.str.redhat.com> (raw)
In-Reply-To: <1418305950-30924-2-git-send-email-pbonzini@redhat.com>
Am 11.12.2014 um 14:52 hat Paolo Bonzini geschrieben:
> Keep a queue of requests that were not submitted; pass them to
> the kernel when a completion is reported, unless the queue is
> plugged.
>
> The array of iocbs is rebuilt every time from scratch. This
> avoids keeping the iocbs array and list synchronized.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Just found out that in qemu-img bench, this patch seems to cost about
5-8% for me.
An optimisation for the unplugged case would probably be easy, but that
would be cheating, as the devices that we're really interested in always
plug the queue (perhaps I should extend qemu-img bench to do that
optionally, too).
Anything clever that we can do about this? Or will we just have to live
with the fact that sending a single request is now slower than it used
to be before bdrv_plug?
Kevin
next prev parent reply other threads:[~2014-12-16 11:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-11 13:52 [Qemu-devel] [PATCH v2 0/5] linux-aio: rewrite and simplify queuing code Paolo Bonzini
2014-12-11 13:52 ` [Qemu-devel] [PATCH v2 1/5] linux-aio: queue requests that cannot be submitted Paolo Bonzini
2014-12-16 11:07 ` Kevin Wolf [this message]
2014-12-16 11:28 ` Paolo Bonzini
2014-12-16 13:10 ` Kevin Wolf
2014-12-16 18:28 ` Paolo Bonzini
2014-12-16 20:26 ` Paolo Bonzini
2014-12-17 12:34 ` Paolo Bonzini
2014-12-17 15:03 ` Paolo Bonzini
2014-12-11 13:52 ` [Qemu-devel] [PATCH v2 2/5] linux-aio: track whether the queue is blocked Paolo Bonzini
2014-12-11 13:52 ` [Qemu-devel] [PATCH v2 3/5] linux-aio: rename LaioQueue idx field to "n" Paolo Bonzini
2014-12-11 13:52 ` [Qemu-devel] [PATCH v2 4/5] linux-aio: drop return code from laio_io_unplug and ioq_submit Paolo Bonzini
2014-12-11 13:52 ` [Qemu-devel] [PATCH v2 5/5] linux-aio: simplify removal of completed iocbs from the list Paolo Bonzini
2014-12-11 14:49 ` [Qemu-devel] [PATCH v2 0/5] linux-aio: rewrite and simplify queuing code Kevin Wolf
2014-12-12 17:07 ` Stefan Hajnoczi
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