From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933513Ab1JDTik (ORCPT ); Tue, 4 Oct 2011 15:38:40 -0400 Received: from perches-mx.perches.com ([206.117.179.246]:44226 "EHLO labridge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933497Ab1JDTij (ORCPT ); Tue, 4 Oct 2011 15:38:39 -0400 Message-ID: <1317757118.3580.24.camel@Joe-Laptop> Subject: Re: big picture UDP/IP performance question re 2.6.18 -> 2.6.32 From: Joe Perches To: Christoph Lameter Cc: starlight@binnacle.cx, Eric Dumazet , linux-kernel@vger.kernel.org, netdev , Willy Tarreau , Peter Zijlstra , Stephen Hemminger Date: Tue, 04 Oct 2011 12:38:38 -0700 In-Reply-To: References: <6.2.5.6.2.20111003112108.03a83a28@binnacle.cx> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.0- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-10-04 at 14:16 -0500, Christoph Lameter wrote: > On Mon, 3 Oct 2011, starlight@binnacle.cx wrote: > > I've come to the conclusion that Eric is right > > and the primary issue is an increase in the > > cost of scheduler context switches. Have > > been watching this number and it has held > > pretty close to 200k/sec under all scenarios > > and kernel versions, so it has to be > > a longer code-path, bigger cache pressure > > or both in the scheduler. Sadly this makes > > newer kernels a no-go for us. > We had similar experiences. Basically latency constantly gets screwed up > by the new fancy features being added to the scheduler and network > subsystem (most notorious is the new "fair" scheduler, 2.6.23 made a big > step down). Idly curious, have you compared bfs performance? http://ck.kolivas.org/patches/bfs/bfs-faq.txt