Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751728AbYLROiU (ORCPT ); Thu, 18 Dec 2008 09:38:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751481AbYLROiH (ORCPT ); Thu, 18 Dec 2008 09:38:07 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:40729 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271AbYLROiE (ORCPT ); Thu, 18 Dec 2008 09:38:04 -0500 Date: Thu, 18 Dec 2008 15:37:52 +0100 From: Ingo Molnar To: Mike Galbraith Cc: Miklos Szeredi , rjw@sisk.pl, a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org Subject: Re: [Bug #12208] uml is very slow on 2.6.28 host Message-ID: <20081218143752.GB10548@elte.hu> References: <1229397927.5296.48.camel@marge.simson.net> <1229437180.5379.76.camel@marge.simson.net> <1229494628.5280.24.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1229494628.5280.24.camel@marge.simson.net> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Galbraith wrote: > On Tue, 2008-12-16 at 16:27 +0100, Miklos Szeredi wrote: > > > Is there a way to trace what is happening in the scheduler? > > Sure. Ingo has a script for gathering info (attached), if you run it, > please gzip up the output and send me a copy offline to eyeball. > > There's also ftrace, but I've not tried that yet, so can't offer any > advice, I use primitive but effective time_after() + printk() with klogd > wakeup disabled (deadlock). btw., there's a recent commit: 32a7600: printk: make printk more robust by not allowing recursion since then printk shouldnt deadlock anymore, even if called from within the scheduler. Btw., ftrace_printk() can be used similarly (and you can capture it nonstop via /debug/tracing/trace_pipe), and should not deadlock either. Ingo -- 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/