Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754576Ab1DLNI3 (ORCPT ); Tue, 12 Apr 2011 09:08:29 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:52635 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750901Ab1DLNI2 (ORCPT ); Tue, 12 Apr 2011 09:08:28 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=Y9ZKGy5I8/3xdU8vzvT4t4F7VzEJTumo/2hc0UV50WxlOfm7VDyakuOXlyuYkCo3vv AgoRxzbFL4Cy7c9M7KT5QEqldFEgQMXUbLGLIZdlpSKKzHofcUVCXbRhGPh1dAtsaSQ6 DzfWqxiPVvmruvoI0GAO3u+CiNVrDZt0uZ3AQ= Subject: Re: Loopback and Nagle's algorithm From: Eric Dumazet To: Jiri Kosina Cc: Adam McLaurin , Will Newton , linux-kernel@vger.kernel.org, netdev In-Reply-To: References: <1302575869.13492.1440076201@webmail.messagingengine.com> <1302606246.21782.1440195277@webmail.messagingengine.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 12 Apr 2011 15:08:23 +0200 Message-ID: <1302613703.3233.40.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1073 Lines: 34 Le mardi 12 avril 2011 à 13:54 +0200, Jiri Kosina a écrit : > On Tue, 12 Apr 2011, Adam McLaurin wrote: > > > > It may be caused by an increase in context switch rate, as both sender > > > and receiver are on the same machine. > > > > I'm not sure that's what's happening, since the box where I'm running > > this test has 8 physical CPU's and 32 cores in total. > > Have you tried firing up the testcase under perf, to see what it reveals > as the bottleneck? > CC netdev This rings a bell here. I suspect we hit mod_timer() / lock_timer_base() because of delack timer constantly changing. I remember raising this point last year : http://kerneltrap.org/mailarchive/linux-netdev/2010/5/20/6277741 David answer : http://kerneltrap.org/mailarchive/linux-netdev/2010/6/2/6278430 I am afraid no change was done... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/