From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756401Ab2GCNbR (ORCPT ); Tue, 3 Jul 2012 09:31:17 -0400 Received: from mail-yw0-f51.google.com ([209.85.213.51]:64694 "EHLO mail-yw0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752252Ab2GCNbQ (ORCPT ); Tue, 3 Jul 2012 09:31:16 -0400 Message-ID: <4FF2F417.2010209@redhat.com> Date: Tue, 03 Jul 2012 15:31:03 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Rusty Russell CC: Asias He , kvm@vger.kernel.org, "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Sasha Levin , 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> In-Reply-To: <8762a6y89v.fsf@rustcorp.com.au> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 02/07/2012 08:41, Rusty Russell ha scritto: >> With the same workload in guest, the guest fires 200K requests to host >> with merges enabled in guest (echo 0 > /sys/block/vdb/queue/nomerges), >> while the guest fires 40000K requests to host with merges disabled in >> guest (echo 2 > /sys/block/vdb/queue/nomerges). This show that the merge >> in block layer reduces the total number of requests fire to host a lot >> (40000K / 200K = 20). >> 40000 / 200 is 200, not 20. :) Paolo