From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:47206)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1XHXmM-0002JZ-SV
	for qemu-devel@nongnu.org; Wed, 13 Aug 2014 08:35:55 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1XHXmD-000175-OO
	for qemu-devel@nongnu.org; Wed, 13 Aug 2014 08:35:46 -0400
Received: from mail-wg0-x22a.google.com ([2a00:1450:400c:c00::22a]:33111)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1XHXmD-000171-Ef
	for qemu-devel@nongnu.org; Wed, 13 Aug 2014 08:35:37 -0400
Received: by mail-wg0-f42.google.com with SMTP id l18so11033205wgh.13
	for <qemu-devel@nongnu.org>; Wed, 13 Aug 2014 05:35:36 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <53EB5B84.20503@redhat.com>
Date: Wed, 13 Aug 2014 14:35:16 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1407209598-2572-1-git-send-email-ming.lei@canonical.com>	<20140805094844.GF4391@noname.str.redhat.com>	<CACVXFVMeu9N9OnTcfGV3EC5HOSBxaxrz2R_aodDG43gusS1dow@mail.gmail.com>	<20140805134815.GD12251@stefanha-thinkpad.redhat.com>	<20140805144728.GH4391@noname.str.redhat.com>	<CACVXFVOyaoHXYpuayk8vOQpUCZ0rjD2rMTKG-wxCKokfarGr_w@mail.gmail.com>	<20140806084855.GA4090@noname.str.redhat.com>	<20140810114624.0305b7af@tom-ThinkPad-T410>	<53E91B5D.4090009@redhat.com>	<CACVXFVPqrJCob8Dn1MtZDOswjiwx8OY10oMsN=b+kxrTh4ZJaA@mail.gmail.com>	<53EA6635.9040600@redhat.com>
	<CACVXFVPxOG5V_sW-BXGm2QiNJgf4DvmJtT6EDDRomc82238S7A@mail.gmail.com>
In-Reply-To: <CACVXFVPxOG5V_sW-BXGm2QiNJgf4DvmJtT6EDDRomc82238S7A@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi
 virtqueue support
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>, Fam Zheng <famz@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>

Il 13/08/2014 12:19, Ming Lei ha scritto:
>> > The problem is that your patches to do touch too much code and subtly
>> > break too much stuff.  The one I wrote does have a little breakage
> Could you give a hint about which stuff are broken? Last time, you mention
> virtio-scsi need to keep AIOCB live after returning, I have fixed it in V1.

They are dataplane-specific, while there's no reason not to have the
same benefits elsewhere.  They are file-specific, while there's no
reason not to have the same benefits for e.g. iSCSI (though iSCSI now
uses coroutines instead of bdrv_aio_*).  They touch AioContext for no
reason, and introduce a bunch of layering violations everywhere.

They are simply the wrong API.

>> > because I don't understand bs->growable 100% and I didn't really put
>> > much effort into it (my deadline being basically "be done as soon as the
>> > shower is free"), and it is ugly as hell, _but_ it should be compatible
>> > with the way the block layer works.
> I will take a careful look to your patch later.
> 
> If coroutine is still there, I think it still can slow down performance.

No, it's not there.  Please try the patch.

Paolo