From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932522AbWCNWND (ORCPT ); Tue, 14 Mar 2006 17:13:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932525AbWCNWNB (ORCPT ); Tue, 14 Mar 2006 17:13:01 -0500 Received: from mustang.oldcity.dca.net ([216.158.38.3]:9095 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S932522AbWCNWNA (ORCPT ); Tue, 14 Mar 2006 17:13:00 -0500 Subject: Re: 2.6.16-rc1: 28ms latency when process with lots of swapped memory exits From: Lee Revell To: Ingo Molnar Cc: linux-kernel , Hugh Dickins In-Reply-To: <20060314212207.GC23458@elte.hu> References: <1142352926.13256.117.camel@mindpipe> <20060314212207.GC23458@elte.hu> Content-Type: text/plain Date: Tue, 14 Mar 2006 17:12:57 -0500 Message-Id: <1142374378.24603.20.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 22:22 +0100, Ingo Molnar wrote: > * 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. > > btw., one good way to get such things fixed is to code up a testcase: a > .c file that just has to be run to reproduce the latency. It might be > less trivial to code that up in some cases (like this one - e.g. you > might have to first get a large chunk of memory swapped out which isnt > easy), but i think it's still worth the effort, as that way you can > gently pressure us lazy upstream maintainers to act quicker, and we can > also easily verify whether the fix does the trick :-) Sure, I'll try. But I've been pounding on this kernel for weeks and only hit this once. And I'm pretty sure I've killed processes with lots of swapped memory. The only new variable was acroread - open 5 PDFs in Firefox tabs, leave it alone for a few days until the kernel swaps it all out, then kill it... Lee