From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [net-next PATCH 1/3] net: make default tx_queue_len configurable Date: Thu, 13 Aug 2015 15:10:33 +0200 Message-ID: <20150813151033.048d73b8@redhat.com> References: <1438203103-27013-2-git-send-email-phil@nwl.cc> <20150729210618.GF32705@breakpoint.cc> <20150729213428.GC15554@orbit.nwl.cc> <20150729.143731.834219016906219771.davem@davemloft.net> <20150811174807.3e00b4da@redhat.com> <20150811162335.GB32353@orbit.nwl.cc> <20150812011347.GA58200@Alexeis-MacBook-Pro.local> <20150813011339.GF32353@orbit.nwl.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Alexei Starovoitov , netdev@vger.kernel.org, brouer@redhat.com To: Phil Sutter Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35489 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751692AbbHMNKe (ORCPT ); Thu, 13 Aug 2015 09:10:34 -0400 In-Reply-To: <20150813011339.GF32353@orbit.nwl.cc> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 13 Aug 2015 03:13:40 +0200 Phil Sutter wrote: > On Tue, Aug 11, 2015 at 06:13:49PM -0700, Alexei Starovoitov wrote: > > In general 'changing the default' may be an acceptable thing, but then > > it needs to strongly justified. How much performance does it bring? > > A quick test on my local VM with veth and netperf (netserver and veth > peer in different netns) I see an increase of about 5% of throughput > when using noqueue instead of the default pfifo_fast. Good that you can show 5% improvement with a single netperf flow. We are saving approx 6 atomic operations avoiding the qdisc code path. This fixes a scalability issue with veth. Thus, the real performance boost will happen with multiple flows and multiple CPU cores in action. You can try with a multi core VM and use super_netperf. https://github.com/borkmann/stuff/blob/master/super_netperf -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer