Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762678AbZAPQC3 (ORCPT ); Fri, 16 Jan 2009 11:02:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754808AbZAPQCP (ORCPT ); Fri, 16 Jan 2009 11:02:15 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:53090 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754696AbZAPQCN (ORCPT ); Fri, 16 Jan 2009 11:02:13 -0500 Date: Fri, 16 Jan 2009 17:02:02 +0100 From: Ingo Molnar To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Andrew Morton , Frederic Weisbecker , Chris Mason Subject: Re: [PATCH 0/2] ftrace: updates to tip Message-ID: <20090116160202.GA15209@elte.hu> References: <20090116004050.273665842@goodmis.org> <20090116112345.GC20082@elte.hu> <20090116152103.GA28643@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Content-Length: 1284 Lines: 33 * Steven Rostedt wrote: > > On Fri, 16 Jan 2009, Ingo Molnar wrote: > > > > > > But I do notice that not all functions produce a valid stack trace. > > > Maybe it would be better to add that api :-? > > > > yes - i think that API would be more intuitive, and that way people could > > mix more interesting functions (with stack traces) with less important > > functions (no stack traces). > > Ah, that's the point. We can't mix and match on these. Either all > functions that are traced do the stack trace, or none do. This is where > the new api may be confusing. [...] that would be confusing indeed. > [...] We can register a function to be traced via the function pointer, > and we can pick which functions to trace, but we can not separate out > different functions for different traces. Why not? We could have a hash of all traced functions with metadata attached. Since patching functions in/out would be a relatively rare operation, this would be a highly efficient read-mostly hash. 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/