Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758609AbZATRyN (ORCPT ); Tue, 20 Jan 2009 12:54:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751534AbZATRx4 (ORCPT ); Tue, 20 Jan 2009 12:53:56 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:63262 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1749667AbZATRx4 (ORCPT ); Tue, 20 Jan 2009 12:53:56 -0500 Date: Tue, 20 Jan 2009 12:53:53 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Ingo Molnar cc: Kevin Shanahan , Avi Kivity , "Rafael J. Wysocki" , Linux Kernel Mailing List , Kernel Testers List , Kevin Shanahan , Mike Galbraith , Peter Zijlstra , =?ISO-8859-15?Q?Fr=E9d=E9ric_Weisbecker?= Subject: Re: [Bug #12465] KVM guests stalling on 2.6.28 (bisected) In-Reply-To: <20090120150408.GD21931@elte.hu> Message-ID: References: <1232410363.4768.21.camel@kulgan.wumi.org.au> <20090120113546.GA26571@elte.hu> <1232455343.4895.4.camel@kulgan.wumi.org.au> <20090120125652.GA1457@elte.hu> <20090120130714.GA11048@elte.hu> <20090120150408.GD21931@elte.hu> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1693 Lines: 46 On Tue, 20 Jan 2009, Ingo Molnar wrote: > > * Steven Rostedt wrote: > > > On Tue, 20 Jan 2009, Ingo Molnar wrote: > > > Another test would be to build the scheduler latency tracer into your > > > kernel: > > > > > > CONFIG_SCHED_TRACER=y > > > > > > And enable it via: > > > > > > echo wakeup > /debug/tracing/current_tracer > > > > > > and you should be seeing the worst-case scheduling latency traces in > > > /debug/tracing/trace, and the largest observed latency will be in > > > /debug/tracing/tracing_max_latency [in microseconds]. > > > > Note, the wakeup latency only tests realtime threads, since other > > threads can have other issues for wakeup. I could change the wakeup > > tracer as wakeup_rt, and make a new "wakeup" that tests all threads, but > > it may be difficult to get something accurate. > > hm, that's a significant regression then. The latency tracer used to > measure the highest-prio task in the system - be that RT or non-rt. Well, it is a regression from what was in -rt yes. But not from what ever was in mainline. But I needed to change this to detect the problem that we solved with push and pull of rt tasks. The wake up of a non-rt tasks always took longer than an -rt task, and by tracing all tasks, I never got the wake up latency of an rt task. As I mentioned earlier, I can make a wakeup-rt to do the rt tracing, and make wakeup do all tasks. -- Steve -- 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/