From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] kvm:virtio-net: Run TX from the I/O thread Date: Thu, 22 Jan 2009 15:41:16 +0200 Message-ID: <4978777C.6020703@redhat.com> References: <20090121230642.10404.65372.stgit@kvm.aw> <1232628422.4533.14.camel@blaa> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Alex Williamson , kvm@vger.kernel.org To: Mark McLoughlin Return-path: Received: from mx2.redhat.com ([66.187.237.31]:41385 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752331AbZAVNlV (ORCPT ); Thu, 22 Jan 2009 08:41:21 -0500 In-Reply-To: <1232628422.4533.14.camel@blaa> Sender: kvm-owner@vger.kernel.org List-ID: Mark McLoughlin wrote: > Hi Alex, > > On Wed, 2009-01-21 at 16:08 -0700, Alex Williamson wrote: > >> This is an attempt to improve the latency of virtio-net while not hurting >> throughput. I wanted to try moving packet TX into a different thread >> so we can quickly return to the guest after it kicks us to send packets >> out. I also switched the order of when the tx_timer comes into play, so >> we can get an inital burst of packets out, then wait for the timer to >> fire and notify us if there's more to do. Here's what it does for me >> (average of 5 runs each, testing to a remote system on a 1Gb network): >> >> netperf TCP_STREAM: 939.22Mb/s -> 935.24Mb/s = 99.58% >> netperf TCP_RR: 2028.72/s -> 3927.99/s = 193.62% >> tbench: 92.99MB/s -> 99.97MB/s = 107.51% >> >> I'd be interested to hear if it helps or hurts anyone else. Thanks, >> > > Avi and I went back and forth on this one in great detail before: > > http://www.mail-archive.com/kvm@vger.kernel.org/msg06431.html > > Avi's arguments make a lot of sense, but looking over those patches > again now, I still think that applying them would be a better approach > than what we have right now. > I can go with that. Anthony, should I wait for a qemu iothread so it can go upstream directly? -- error compiling committee.c: too many arguments to function