From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:44451)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1X1rN3-0001VW-Oe
	for qemu-devel@nongnu.org; Tue, 01 Jul 2014 02:16:58 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1X1rMp-0005CY-VQ
	for qemu-devel@nongnu.org; Tue, 01 Jul 2014 02:16:49 -0400
Received: from mail-wi0-x233.google.com ([2a00:1450:400c:c05::233]:48473)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1X1rMp-0005C0-O5
	for qemu-devel@nongnu.org; Tue, 01 Jul 2014 02:16:35 -0400
Received: by mail-wi0-f179.google.com with SMTP id cc10so7128421wib.0
	for <qemu-devel@nongnu.org>; Mon, 30 Jun 2014 23:16:34 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <53B25229.6050105@redhat.com>
Date: Tue, 01 Jul 2014 08:16:09 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1404143260-9368-1-git-send-email-ming.lei@canonical.com>	<1404143260-9368-3-git-send-email-ming.lei@canonical.com>	<53B19ED4.1090508@redhat.com>
	<CACVXFVNE1qH30FM63OFU1taVx6Z4T_Ki5_Rr1Wa527bVhQoCaA@mail.gmail.com>
In-Reply-To: <CACVXFVNE1qH30FM63OFU1taVx6Z4T_Ki5_Rr1Wa527bVhQoCaA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v1 2/3] linux-aio: implement io plug and
	unplug
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Ming Lei <ming.lei@canonical.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Fam Zheng <famz@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>

Il 01/07/2014 03:05, Ming Lei ha scritto:
>> > Busy waiting is not acceptable here (it can be unbounded if, for example, an
>> > NFS server is on the other side of a network partition). You have to add a
>> > bottom half to qemu_laio_state that calls ioq_submit, and schedule it after
>> > calling io_getevents.
>> >
>> > If the bottom half is already scheduled and the queue is full, I guess
>> > there's no other choice than returning -EAGAIN from ioq_enqueue and
>> > ultimately to the guest.
> That is a bit complicated, as you mentioned it is close to
> 2.1 release, could we just keep it simple to return failure to guest
> after retrying several times? Actually, previous dataplane handles
> it by exit(-1), which is unfriendly absolutely.

Indeed, I'd say do not even bother retrying several times. :)

Paolo