From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932079AbVHSDfD (ORCPT ); Thu, 18 Aug 2005 23:35:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932118AbVHSDfB (ORCPT ); Thu, 18 Aug 2005 23:35:01 -0400 Received: from mustang.oldcity.dca.net ([216.158.38.3]:26832 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S932086AbVHSDfA (ORCPT ); Thu, 18 Aug 2005 23:35:00 -0400 Subject: Re: [RFC] IPV4 long lasting timer function From: Lee Revell To: tglx@linutronix.de Cc: "David S. Miller" , Ingo Molnar , LKML In-Reply-To: <1124312341.23647.277.camel@tglx.tec.linutronix.de> References: <1124312341.23647.277.camel@tglx.tec.linutronix.de> Content-Type: text/plain Date: Thu, 18 Aug 2005 23:34:57 -0400 Message-Id: <1124422498.25424.13.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.3.7 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2005-08-17 at 22:59 +0200, Thomas Gleixner wrote: > Hi, > > while tracking down some timer related ugliness I stumbled over the > timer driven function rt_secret_rebuild(), which does a loop over > rt_has_mask (1024 in my case) entries and possibly some subsequent > variable sized loops inside each step. > > On a 300MHZ PPC system this accumulated to a worst case total of >5ms. I > could not reproduce it with this magnitude, but applying heavy > networking load is definitely triggering this behaviour. > > Shouldn't this be converted to a workqueue, which gets triggered by a > timer instead of blocking the timer softirq and therefor the delivery of > other timer functions that long ? Wow, blast from the past! This was one of the very first problematic code paths Ingo and I identified in the early days of the voluntary preempt patch (using the crude ALSA xrun debug mechanism which was the best we had before /proc/latency_trace). IIRC I was able to trivially reproduce it by leaving gtk-gnutella running overnight with a few active searches/downloads. Lee