From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161291AbXDKXAB (ORCPT ); Wed, 11 Apr 2007 19:00:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161401AbXDKXAA (ORCPT ); Wed, 11 Apr 2007 19:00:00 -0400 Received: from mx1.redhat.com ([66.187.233.31]:46828 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161291AbXDKW7q (ORCPT ); Wed, 11 Apr 2007 18:59:46 -0400 To: Andrew Morton Cc: Mathieu Desnoyers , linux-kernel@vger.kernel.org, Russell King , systemtap@sources.redhat.com Subject: Re: [PATCH] markers-linker-generic References: <20070410223658.GC7092@Krystal> <20070411074414.GC3752@flint.arm.linux.org.uk> <20070411175110.GA30879@Krystal> <20070411110240.537ee25d.akpm@linux-foundation.org> From: fche@redhat.com (Frank Ch. Eigler) Date: 11 Apr 2007 18:58:50 -0400 In-Reply-To: <20070411110240.537ee25d.akpm@linux-foundation.org> Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: > [...] I am told that the systemtap developers plan to (or are) > using this infrastructure. Indeed. > If correct: what is their reason for preferring it over kprobes? > [...] It's not a preference - it's more of a supplement. It's helpful when some combination of such factors exists: - kprobe int3-fault dispatching overhead orders of magnitude too high - fault dispatching not permissible in some areas - local context variables not easily retrievable via dwarf information - dwarf information not available at all - costs of permanently placed but passive marker acceptable >>From systemtap's point of view, instrumentation hooked to markers, kprobes, and other facilities like timers, coexist just fine. A greater number of probe-able event sources makes for a richer tool. - FChE