From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268544AbUHaXHx (ORCPT ); Tue, 31 Aug 2004 19:07:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269115AbUHaXGw (ORCPT ); Tue, 31 Aug 2004 19:06:52 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:45287 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S269204AbUHaXDU (ORCPT ); Tue, 31 Aug 2004 19:03:20 -0400 Subject: Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q5 From: Lee Revell To: Ingo Molnar Cc: Daniel Schmitt , "K.R. Foley" , Felipe Alfaro Solana , linux-kernel , Mark_H_Johnson@raytheon.com, tytso@mit.edu In-Reply-To: <20040831065327.GA30631@elte.hu> References: <200408282210.03568.pnambic@unu.nu> <20040828203116.GA29686@elte.hu> <1093727453.8611.71.camel@krustophenia.net> <20040828211334.GA32009@elte.hu> <1093727817.860.1.camel@krustophenia.net> <1093737080.1385.2.camel@krustophenia.net> <1093746912.1312.4.camel@krustophenia.net> <20040829054339.GA16673@elte.hu> <20040830090608.GA25443@elte.hu> <1093934448.5403.4.camel@krustophenia.net> <20040831065327.GA30631@elte.hu> Content-Type: text/plain Message-Id: <1093993396.3404.17.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Tue, 31 Aug 2004 19:03:17 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2004-08-31 at 02:53, Ingo Molnar wrote: > > > > > > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc1-bk4-Q5 > > ok. It seems the random driver is _mostly_ in shape latency-wise, except > the IP rekeying visible in the above trace. To solve this problem, could > you try the patch below, ontop of -Q5? It moves the random seed > generation outside of the spinlock - AFAICS the spinlock is only needed > to protect the IP sequence counter itself. This solves the problem with the random driver. The worst latencies I am seeing are in netif_receive_skb(). With netdev_max_backlog set to 8, the worst is about 160 usecs: http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-Q5#/var/www/2.6.9-rc1-Q5/trace2.txt http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-Q5#/var/www/2.6.9-rc1-Q5/trace3.txt Setting netdev_max_backlog to 1 has no effect: http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-Q5#/var/www/2.6.9-rc1-Q5/trace4.txt I would expect this one to scale with CPU speed, so this is pretty good considering my relatively underpowered system. I would imagine on a fast UP system you would not see any latencies worse than 100 usecs. Lee