From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751793AbYHSEA3 (ORCPT ); Tue, 19 Aug 2008 00:00:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750788AbYHSEAU (ORCPT ); Tue, 19 Aug 2008 00:00:20 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:39738 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1749667AbYHSEAT (ORCPT ); Tue, 19 Aug 2008 00:00:19 -0400 Date: Tue, 19 Aug 2008 00:00:17 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Mathieu Desnoyers cc: Benjamin Herrenschmidt , Scott Wood , Eran Liberty , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Steven Rostedt , "Paul E. McKenney" Subject: Re: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3) In-Reply-To: <20080819033618.GA24085@Krystal> Message-ID: References: <48A9901B.1080900@redhat.com> <20080818154746.GA26835@Krystal> <48A9AFA7.8080508@freescale.com> <1219110814.8062.2.camel@pasglop> <1219113549.8062.13.camel@pasglop> <20080819024707.GA22659@Krystal> <20080819033618.GA24085@Krystal> 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 On Mon, 18 Aug 2008, Mathieu Desnoyers wrote: > > > > > > > > > > Argh. See text_poke(). It's there exactly for this purpose on x86. > > > > Ouch, I just did. text_poke is quite heavy. It would be interesting to see > > that performed on 20,000 locations at one time. I could play with it, but > > I'm a bit nervous. > > > > It's alread used to modify the LOCK prefixes in alternative.c and did > not seem to be too slow for that.. it should therefore be ok. There's a lot more functions than locks ;-) Anyway, this is only needed after system boot up. But then we do it ever time we start or stop tracing. I'll try it out and see if it is noticable. -- Steve