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, 03 Jul 2012 22:02:05 +0800 Message-ID: <4FF2FB5D.5030102@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> <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> <4FF2F417.2010209@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4FF2F417.2010209@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 To: Paolo Bonzini Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Sasha Levin , Christoph Hellwig List-Id: virtualization@lists.linuxfoundation.org On 07/03/2012 09:31 PM, Paolo Bonzini wrote: > 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. :) Crap, I wrote one more zero here. Actually, it is 4000K. So the factor is still 4000K/200k = 20 ;-) -- Asias