From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [v3 RFC PATCH 0/4] Implement multiqueue virtio-net Date: Thu, 28 Oct 2010 07:50:54 +0200 Message-ID: <20101028055054.GG5599@redhat.com> References: <20101020085452.15579.76002.sendpatchset@krkumar2.in.ibm.com> <20101025161718.GA19559@redhat.com> <20101026093846.GA6766@redhat.com> <20101026110913.GC7922@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: anthony@codemonkey.ws, arnd@arndb.de, avi@redhat.com, davem@davemloft.net, eric.dumazet@gmail.com, kvm@vger.kernel.org, netdev@vger.kernel.org, rusty@rustcorp.com.au To: Krishna Kumar2 Return-path: Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Oct 28, 2010 at 10:44:14AM +0530, Krishna Kumar2 wrote: > "Michael S. Tsirkin" wrote on 10/26/2010 04:39:13 PM: > > (merging two posts into one) > > > I think we discussed the need for external to guest testing > > over 10G. For large messages we should not see any change > > but you should be able to get better numbers for small messages > > assuming a MQ NIC card. > > For external host, there is a contention among different > queues (vhosts) when packets are processed in tun/bridge, > unless I implement MQ TX for macvtap (tun/bridge?). So > my testing shows a small improvement (1 to 1.5% average) > in BW and a rise in SD (between 10-15%). For remote host, > I think tun/macvtap needs MQ TX support? Confused. I thought this *is* with a multiqueue tun/macvtap? bridge does not do any queueing AFAIK ... I think we need to fix the contention. With migration what was guest to host a minute ago might become guest to external now ... > > > > > Results for UDP BW tests (unidirectional, sum across > > > > > 3 iterations, each iteration of 45 seconds, default > > > > > netperf, vhosts bound to cpus 0-3; no other tuning): > > > > > > > > Is binding vhost threads to CPUs really required? > > > > What happens if we let the scheduler do its job? > > > > > > Nothing drastic, I remember BW% and SD% both improved a > > > bit as a result of binding. > > > > If there's a significant improvement this would mean that > > we need to rethink the vhost-net interaction with the scheduler. > > I will get a test run with and without binding and post the > results later today. > > Thanks, > > - KK