From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754710Ab1F2KgS (ORCPT ); Wed, 29 Jun 2011 06:36:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11571 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753247Ab1F2KgP (ORCPT ); Wed, 29 Jun 2011 06:36:15 -0400 Message-ID: <4E0B0007.3050901@redhat.com> Date: Wed, 29 Jun 2011 12:35:51 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Mnenhy/0.8.3 Thunderbird/3.1.10 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: Christoph Hellwig , Hannes Reinecke , Linux Virtualization , Linux Kernel Mailing List , qemu-devel , Rusty Russell , Stefan Hajnoczi , Christoph Hellwig , "kvm@vger.kernel.org" Subject: Re: virtio scsi host draft specification, v3 References: <4DEE2B15.4090809@redhat.com> <4DF21447.6090005@suse.de> <20110612075140.GB11941@redhat.com> <4E0AE0FE.2090905@redhat.com> <20110629100341.GC22900@infradead.org> <4E0AF925.2050707@redhat.com> <20110629103139.GC16757@redhat.com> In-Reply-To: <20110629103139.GC16757@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/29/2011 12:31 PM, Michael S. Tsirkin wrote: > On Wed, Jun 29, 2011 at 12:06:29PM +0200, Paolo Bonzini wrote: >> On 06/29/2011 12:03 PM, Christoph Hellwig wrote: >>>> I agree here, in fact I misread Hannes's comment as "if a driver >>>> uses more than one queue it is responsibility of the driver to >>>> ensure strict request ordering". If you send requests to different >>>> queues, you know that those requests are independent. I don't think >>>> anything else is feasible in the virtio framework. >>> >>> That doesn't really fit very well with the SAM model. If we want >>> to use multiple queues for a single LUN it has to be transparent to >>> the SCSI command stream. Then again I don't quite see the use for >>> that anyway. >> >> Agreed, I see a use for multiple queues (MSI-X), but not for >> multiple queues shared by a single LUN. > > Then let's make it explicit in the spec? What, forbid it or say ordering is not guaranteed? The latter is already explicit with the wording suggested in the thread. Paolo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:55279) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qbs7v-0008Nw-HQ for qemu-devel@nongnu.org; Wed, 29 Jun 2011 06:36:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Qbs7t-0000R5-IA for qemu-devel@nongnu.org; Wed, 29 Jun 2011 06:36:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34700) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qbs7t-0000Qs-3n for qemu-devel@nongnu.org; Wed, 29 Jun 2011 06:36:09 -0400 Message-ID: <4E0B0007.3050901@redhat.com> Date: Wed, 29 Jun 2011 12:35:51 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <4DEE2B15.4090809@redhat.com> <4DF21447.6090005@suse.de> <20110612075140.GB11941@redhat.com> <4E0AE0FE.2090905@redhat.com> <20110629100341.GC22900@infradead.org> <4E0AF925.2050707@redhat.com> <20110629103139.GC16757@redhat.com> In-Reply-To: <20110629103139.GC16757@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] virtio scsi host draft specification, v3 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Christoph Hellwig , Stefan Hajnoczi , "kvm@vger.kernel.org" , Rusty Russell , Linux Kernel Mailing List , qemu-devel , Christoph Hellwig , Hannes Reinecke , Linux Virtualization On 06/29/2011 12:31 PM, Michael S. Tsirkin wrote: > On Wed, Jun 29, 2011 at 12:06:29PM +0200, Paolo Bonzini wrote: >> On 06/29/2011 12:03 PM, Christoph Hellwig wrote: >>>> I agree here, in fact I misread Hannes's comment as "if a driver >>>> uses more than one queue it is responsibility of the driver to >>>> ensure strict request ordering". If you send requests to different >>>> queues, you know that those requests are independent. I don't think >>>> anything else is feasible in the virtio framework. >>> >>> That doesn't really fit very well with the SAM model. If we want >>> to use multiple queues for a single LUN it has to be transparent to >>> the SCSI command stream. Then again I don't quite see the use for >>> that anyway. >> >> Agreed, I see a use for multiple queues (MSI-X), but not for >> multiple queues shared by a single LUN. > > Then let's make it explicit in the spec? What, forbid it or say ordering is not guaranteed? The latter is already explicit with the wording suggested in the thread. Paolo