From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [PATCH 3/3] virtio-blk: Add bio-based IO path for virtio-blk Date: Mon, 18 Jun 2012 19:35:22 +0930 Message-ID: <87zk81x7dp.fsf@rustcorp.com.au> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Christoph Hellwig To: Asias He Return-path: In-Reply-To: <4FDEE0CB.1030505@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 Mon, 18 Jun 2012 16:03:23 +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. Users using a spinning disk still get IO scheduling in the host though. What benefit is there in doing it in the guest as well? Cheers, Rusty.