From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753924Ab2FSCUQ (ORCPT ); Mon, 18 Jun 2012 22:20:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54660 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751726Ab2FSCUO (ORCPT ); Mon, 18 Jun 2012 22:20:14 -0400 Message-ID: <4FDFE22E.3030003@redhat.com> Date: Tue, 19 Jun 2012 10:21:34 +0800 From: Asias He User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: Rusty Russell , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Christoph Hellwig , Minchan Kim Subject: Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk References: <1340002390-3950-1-git-send-email-asias@redhat.com> <1340002390-3950-4-git-send-email-asias@redhat.com> <87hau9yse7.fsf@rustcorp.com.au> <4FDEE0CB.1030505@redhat.com> <20120618101349.GC23134@redhat.com> In-Reply-To: <20120618101349.GC23134@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/18/2012 06:13 PM, Michael S. Tsirkin wrote: > On Mon, Jun 18, 2012 at 04:03:23PM +0800, Asias He wrote: >> On 06/18/2012 03:46 PM, Rusty Russell wrote: >>> On Mon, 18 Jun 2012 14:53:10 +0800, Asias He wrote: >>>> This patch introduces bio-based IO path for virtio-blk. >>> >>> Why make it optional? >> >> request-based IO path is useful for users who do not want to bypass >> the IO scheduler in guest kernel, e.g. users using spinning disk. >> For users using fast disk device, e.g. SSD device, they can use >> bio-based IO path. > > OK I guess but then it should be per-device. There could be > a mix of slow and fast disks :) Yes, per-device might be useful. There are issues which need solving. - How do we tell the drive which IO path to use - Device add some flag - Old qemu/lkvm can not turn this feature on - Through /sys filesystem attribute - How do we handle the switch from one path to anther. So, let's add the per-device feature later. -- Asias From mboxrd@z Thu Jan 1 00:00:00 1970 From: Asias He Subject: Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk Date: Tue, 19 Jun 2012 10:21:34 +0800 Message-ID: <4FDFE22E.3030003@redhat.com> References: <1340002390-3950-1-git-send-email-asias@redhat.com> <1340002390-3950-4-git-send-email-asias@redhat.com> <87hau9yse7.fsf@rustcorp.com.au> <4FDEE0CB.1030505@redhat.com> <20120618101349.GC23134@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Christoph Hellwig To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20120618101349.GC23134@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: kvm.vger.kernel.org On 06/18/2012 06:13 PM, Michael S. Tsirkin wrote: > On Mon, Jun 18, 2012 at 04:03:23PM +0800, Asias He wrote: >> On 06/18/2012 03:46 PM, Rusty Russell wrote: >>> On Mon, 18 Jun 2012 14:53:10 +0800, Asias He wrote: >>>> This patch introduces bio-based IO path for virtio-blk. >>> >>> Why make it optional? >> >> request-based IO path is useful for users who do not want to bypass >> the IO scheduler in guest kernel, e.g. users using spinning disk. >> For users using fast disk device, e.g. SSD device, they can use >> bio-based IO path. > > OK I guess but then it should be per-device. There could be > a mix of slow and fast disks :) Yes, per-device might be useful. There are issues which need solving. - How do we tell the drive which IO path to use - Device add some flag - Old qemu/lkvm can not turn this feature on - Through /sys filesystem attribute - How do we handle the switch from one path to anther. So, let's add the per-device feature later. -- Asias