From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:57730)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <s.priebe@profihost.ag>) id 1Szo6h-0002Ke-6X
	for qemu-devel@nongnu.org; Fri, 10 Aug 2012 08:14:24 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <s.priebe@profihost.ag>) id 1Szo6d-0001xW-2m
	for qemu-devel@nongnu.org; Fri, 10 Aug 2012 08:14:23 -0400
Received: from mail.profihost.ag ([85.158.179.208]:34139)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <s.priebe@profihost.ag>) id 1Szo6c-0001xF-Py
	for qemu-devel@nongnu.org; Fri, 10 Aug 2012 08:14:19 -0400
Message-ID: <5024FB17.7060706@profihost.ag>
Date: Fri, 10 Aug 2012 14:14:15 +0200
From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
MIME-Version: 1.0
References: <502283FA.2080506@profihost.ag> <5022912B.2000607@redhat.com>
	<50235527.4090804@profihost.ag> <50236059.7060801@redhat.com>
	<4A799203-5BFF-4DE9-9B85-459096EBEC22@profihost.ag>
	<50236484.2090702@redhat.com> <502369C7.7000300@profihost.ag>
	<CAJSP0QWXNcaGg=R5wOvzd_UVW2xNkGWS_7m8oQKpYpk4OcpLMg@mail.gmail.com>
	<50238E2A.1050203@profihost.ag> <5024D2E7.40700@profihost.ag>
	<5024E06A.4070603@redhat.com> <5024E232.5020706@profihost.ag>
	<5024E2CB.2050208@redhat.com>
	<CAN05THTUC36MU9oNrw3sDjFLb=8PFwL4WQj1JxZOV6vBCZU7jg@mail.gmail.com>
	<5024F73E.2060609@profihost.ag>
	<CAN05THTK_Nmj96tmFQJjfOtvBbGgGu1KfmrPYzFrHpbRshW6Qw@mail.gmail.com>
In-Reply-To: <CAN05THTK_Nmj96tmFQJjfOtvBbGgGu1KfmrPYzFrHpbRshW6Qw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] virtio-scsi vs. virtio-blk
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: ronnie sahlberg <ronniesahlberg@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@gmail.com>

Am 10.08.2012 14:04, schrieb ronnie sahlberg:
> On Fri, Aug 10, 2012 at 9:57 PM, Stefan Priebe - Profihost AG
> <s.priebe@profihost.ag> wrote:
>> Am 10.08.2012 13:12, schrieb ronnie sahlberg:
>>
>>> You want discard to work?
>>
>> Yes
>>
>>
>>> You are using qemu 1.0 ?
>>
>> actual qemu-kvm git
>>
>>
>>> So you dont have the qemu support for scsi-generic passthrough to iscsi
>>> devices.
>>
>> Why?
>>
>
> scsi-generic passthrough I think was added for iscsi in 1.1
> so in 1.0 your guest will talk scsi to qemu, and invoke the
> scsi-emulation in qemu.
> It then will call functions like 'bdrv_aio_discard()" in libiscsi
> that will translate it back into a scsi command again and pass it to
> the target.
>
> It still works, it just means you have a small degradation of
> performance compared to if you could send the SCSI CDB straight
> through to the iscsi target as you can in qemu 1.1
> Very likely so small performance hit that you can not even measure it.

which version are you talking about? I use qemu-kvm.git so this is 
upcomming 1.2 and i use libiscsi 1.5.0.

Greets,
Stefan