From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753299Ab2GFBBh (ORCPT ); Thu, 5 Jul 2012 21:01:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38475 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752157Ab2GFBBf (ORCPT ); Thu, 5 Jul 2012 21:01:35 -0400 Message-ID: <4FF63954.5040408@redhat.com> Date: Fri, 06 Jul 2012 09:03:16 +0800 From: Asias He User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: Rusty Russell CC: Sasha Levin , dlaor@redhat.com, kvm@vger.kernel.org, "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Christoph Hellwig 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> <87zk81x7dp.fsf@rustcorp.com.au> <4FDF0DA7.40604@redhat.com> <1340019575.22848.2.camel@lappy> <4FDFE926.7030309@redhat.com> <87r4svxcjw.fsf@rustcorp.com.au> <4FF10B31.60609@redhat.com> <8762a6y89v.fsf@rustcorp.com.au> <4FF23F4B.2040803@redhat.com> <87lij0w8np.fsf@rustcorp.com.au> In-Reply-To: <87lij0w8np.fsf@rustcorp.com.au> 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 07/04/2012 10:40 AM, Rusty Russell wrote: > On Tue, 03 Jul 2012 08:39:39 +0800, Asias He wrote: >> On 07/02/2012 02:41 PM, Rusty Russell wrote: >>> Sure, our guest merging might save us 100x as many exits as no merging. >>> But since we're not doing many requests, does it matter? >> >> We can still have many requests with slow devices. The number of >> requests depends on the workload in guest. E.g. 512 IO threads in guest >> keeping doing IO. > > You can have many requests outstanding. But if the device is slow, the > rate of requests being serviced must be low. Yes. > Am I misunderstanding something? I thought if you could have a high > rate of requests, it's not a slow device. Sure. -- Asias