From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750766AbWCNTFu (ORCPT ); Tue, 14 Mar 2006 14:05:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751988AbWCNTFt (ORCPT ); Tue, 14 Mar 2006 14:05:49 -0500 Received: from viper.oldcity.dca.net ([216.158.38.4]:52127 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S1750766AbWCNTFs (ORCPT ); Tue, 14 Mar 2006 14:05:48 -0500 Subject: Re: 2.6.16-rc1: 28ms latency when process with lots of swapped memory exits From: Lee Revell To: Hugh Dickins Cc: linux-kernel , Ingo Molnar In-Reply-To: References: <1142352926.13256.117.camel@mindpipe> Content-Type: text/plain Date: Tue, 14 Mar 2006 14:05:45 -0500 Message-Id: <1142363146.13256.145.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.5.92 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2006-03-14 at 18:40 +0000, Hugh Dickins wrote: > On Tue, 14 Mar 2006, Lee Revell wrote: > > > I've been testign for weeks with 2.6.16-rc1 + the latency trace patch > > and the longest latencies measured were 10-15ms due to the well known > > rt_run_flush issue. Today I got one twice as long, when a Firefox > > process with a bunch of acroreads in tabs, from a new code path. > > > > It seems to trigger when a process with a large amount of memory swapped > > out exits. > > > > Can this be solved with a cond_resched? > > Not that easily, I think. > > Are you testing with CONFIG_PREEMPT=y, as I'd expect? I thought > cond_resched() adds nothing to that case (and we keep on intending > but forgetting to make it compile away to nothing in that case). > Or am I confused? > Thanks for the explanation - I am the one confused (PREEMPT is on so cond_resched would be pointless). Lee