Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754895AbYLTBqs (ORCPT ); Fri, 19 Dec 2008 20:46:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752581AbYLTBqk (ORCPT ); Fri, 19 Dec 2008 20:46:40 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:55487 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752326AbYLTBqj (ORCPT ); Fri, 19 Dec 2008 20:46:39 -0500 Date: Fri, 19 Dec 2008 20:46:38 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Pekka Paalanen cc: Ingo Molnar , =?ISO-8859-15?Q?Fr=E9d=E9ric_Weisbecker?= , Pekka J Enberg , LKML , Markus Metzger Subject: Re: ftrace behaviour (was: [PATCH] ftrace: introduce tracing_reset_online_cpus() helper) In-Reply-To: <20081220033822.362bc88a@daedalus.pq.iki.fi> Message-ID: References: <20081220004453.50aec846@daedalus.pq.iki.fi> <20081219225717.GK13409@elte.hu> <20081219233443.GC17984@elte.hu> <20081220033822.362bc88a@daedalus.pq.iki.fi> 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: 1126 Lines: 34 On Sat, 20 Dec 2008, Pekka Paalanen wrote: > On Fri, 19 Dec 2008 19:29:30 -0500 (EST) > Steven Rostedt wrote: > > I thought this was just about not having to do > > $ echo 0 > tracing_enabled > $ echo 28764243 > buffer_size > $ echo 1 > tracing_enabled > > and instead just do > > $ echo 28764243 > buffer_size > > which would do exactly the same, except being easier for the user. > Personally I've never dreamed of any kind of resize-in-flight. > To implement this at the ftrace level should be a trivial change. I'm just saying that doing this at the "ring buffer" level might be a bit more complex. The ring buffer has no idea of ftrace. It should not. It is at a lower lever than ftrace. Although, I do think some of the protecting that is done at the tracing level during resize should be moved down into the ring buffer layer. -- 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/