From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753911Ab2GWFwk (ORCPT ); Mon, 23 Jul 2012 01:52:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59859 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753652Ab2GWFwi (ORCPT ); Mon, 23 Jul 2012 01:52:38 -0400 Message-ID: <500CE72B.2040101@redhat.com> Date: Mon, 23 Jul 2012 13:54:51 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120210 Thunderbird/10.0.1 MIME-Version: 1.0 To: Sasha Levin CC: "Michael S. Tsirkin" , mashirle@us.ibm.com, krkumar2@in.ibm.com, habanero@linux.vnet.ibm.com, rusty@rustcorp.com.au, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, edumazet@google.com, tahm@linux.vnet.ibm.com, jwhan@filewood.snu.ac.kr, davem@davemloft.net, akong@redhat.com, kvm@vger.kernel.org, sri@us.ibm.com Subject: Re: [net-next RFC V5 4/5] virtio_net: multiqueue support References: <1341484194-8108-1-git-send-email-jasowang@redhat.com> <1341484194-8108-5-git-send-email-jasowang@redhat.com> <20120720134014.GD16550@redhat.com> <500A9A72.20507@gmail.com> In-Reply-To: <500A9A72.20507@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/21/2012 08:02 PM, Sasha Levin wrote: > On 07/20/2012 03:40 PM, Michael S. Tsirkin wrote: >>> - err = init_vqs(vi); >>>> + if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) >>>> + vi->has_cvq = true; >>>> + >> How about we disable multiqueue if there's no cvq? >> Will make logic a bit simpler, won't it? > multiqueues don't really depend on cvq. Does this added complexity really justifies adding an artificial limit? > Yes, it does not depends on cvq. Cvq were just used to negotiate the number of queues a guest wishes to use which is really useful (at least for now). Since multiqueue can not out-perform for single queue in every kinds of workloads or benchmark, so we want to let guest driver use single queue by default even when multiqueue were enabled by management software and let use to enalbe it through ethtool. So user could not feel regression when it switch to use a multiqueue capable driver and backend. So the only difference is the user experiences. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/