Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764475AbYARXNW (ORCPT ); Fri, 18 Jan 2008 18:13:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758529AbYARXNL (ORCPT ); Fri, 18 Jan 2008 18:13:11 -0500 Received: from mx1.redhat.com ([66.187.233.31]:52157 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762387AbYARXNJ (ORCPT ); Fri, 18 Jan 2008 18:13:09 -0500 Date: Fri, 18 Jan 2008 18:11:09 -0500 From: "Frank Ch. Eigler" To: Arjan van de Ven Cc: "Frank Ch. Eigler" , Arjan van de Ven , Linux Kernel Mailing List , Linus Torvalds , Ingo Molnar , Andrew Morton Subject: Re: [patch 2/3] Latencytop instrumentations part 1 Message-ID: <20080118231109.GC27193@redhat.com> References: <4790E3A6.7060807@linux.intel.com> <20080118094048.10e79ff9@laptopd505.fenrus.org> <20080118143334.28ba08ca@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080118143334.28ba08ca@laptopd505.fenrus.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1233 Lines: 28 Hi - On Fri, Jan 18, 2008 at 02:33:34PM -0800, Arjan van de Ven wrote: > [...] > > Can you suggest of some reason why all this instrumentation could > > not be in the form of standard markers (perhaps conditionally > > compiled out if necessary)? > > sure. Every instrumentation you see is of the nested kind (since the lowest level > of nesting is already automatic via wchan). > If markers can provide me the following semantics, I'd be MORE than happy to use markers: > [...] > If markers can provide that semantics ... you sold me. Further to what acme said, markers are semantics-free. Callback functions that implement your entry & exit semantics can be attached at run time, at your pleasure. (So can systemtap probes, for that matter.) The main difference would be that these callback functions would have manage the per-thread LIFO data structures themselves, instead of allocating backpointers on the kernel stack. (Bonus marks for not modifying task_struct. :-) - FChE -- 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/