From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: Network latency regressions from 2.6.22 to 2.6.29 (results with IRQ affinity) Date: Sat, 18 Apr 2009 10:20:28 +0200 Message-ID: <49E98D4C.8020406@cosmosbay.com> References: <49E78A79.6050604@cosmosbay.com> <49E78C1E.9060405@cosmosbay.com> <20090416.160002.09845606.davem@davemloft.net> <49E98CCE.2000701@cosmosbay.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Christoph Lameter , David Miller , Michael Chan , Ben Hutchings , netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:39029 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754366AbZDRIVM convert rfc822-to-8bit (ORCPT ); Sat, 18 Apr 2009 04:21:12 -0400 In-Reply-To: <49E98CCE.2000701@cosmosbay.com> Sender: netdev-owner@vger.kernel.org List-ID: Eric Dumazet a =E9crit : > Christoph Lameter a =E9crit : >> On Thu, 16 Apr 2009, David Miller wrote: >> >>> We really need to find a good way to fix that IRQ affinity issue. >> Here are the results with setting interrupt affinity. We are still l= oosing >> 5 usecs from .22 to .30-rc2. We will investigate more in depth time >> permitting. >> >> UDP ping pong 40 bytes >> >> Kernel Test 1 Test 2 Test 3 Test 4 Avg >> 2.6.22 83.1125 83.4 83.03 82.95 83.07 >> 2.6.23 83.33 83.51 83.18 83.42 83.21 >> 2.6.24 82.7775 82.8 82.77 82.77 82.77 >> 2.6.25 85.875 85.94 85.75 86.06 85.75 >> 2.6.26 87.4025 87.53 87.25 87.3 87.53 >> 2.6.27 87.81 87.81 87.77 87.82 87.84 >> 2.6.28 87.4275 87.77 87.24 87.28 87.42 >> 2.6.29 88.4325 88.48 88.42 88.44 88.39 >> 2.6.30-rc2 88.4925 88.49 88.44 88.56 88.48 >=20 >=20 > You are using UDP, and UDP got memory accounting. This=20 This could explain a slowdown, but not 2.5 us per packet (I take half your 5us, since you are measuring the two ways latencies)