Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269135AbUICDEb (ORCPT ); Thu, 2 Sep 2004 23:04:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269119AbUICDDq (ORCPT ); Thu, 2 Sep 2004 23:03:46 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:50571 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S269252AbUIBWGx (ORCPT ); Thu, 2 Sep 2004 18:06:53 -0400 Subject: Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-R0 From: Lee Revell To: Ingo Molnar Cc: linux-kernel , "K.R. Foley" , Felipe Alfaro Solana , Daniel Schmitt , Mark_H_Johnson@raytheon.com, "P.O. Gaillard" In-Reply-To: <20040902215728.GA28571@elte.hu> References: <20040902063335.GA17657@elte.hu> <20040902065549.GA18860@elte.hu> <20040902111003.GA4256@elte.hu> <20040902215728.GA28571@elte.hu> Content-Type: text/plain Message-Id: <1094162812.1347.54.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Thu, 02 Sep 2004 18:06:53 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1379 Lines: 36 On Thu, 2004-09-02 at 17:57, Ingo Molnar wrote: > i've released the -R0 patch: > > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc1-bk4-R0 > > ontop of: > > http://redhat.com/~mingo/voluntary-preempt/diff-bk-040828-2.6.8.1.bz2 > > i've given up on the netdev_backlog_granularity approach, and as a > replacement i've modified specific network drivers to return at a safe > point if softirq preemption is requested. Makes sense, netdev_max_backlog never made a difference on my system (via-rhine driver). If you read that Microsoft paper I posted a link to earlier, they describe all of the main categories of latencies we have dealt with. They give special mention to network driver DPCs/softirqs. The worst offender was a driver that used a DPC/softirq to reset the card if there was no traffic in 10 seconds, to work around a hardware lockup bug in some versions. Since the reset path was never designed to be fast this caused problems. They also mention a similar problem to the one that still exists with the via-rhine driver (fixed in -mm) where it uses a DPC to poll for link status. Lee - 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/