Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755052AbZCULWi (ORCPT ); Sat, 21 Mar 2009 07:22:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753089AbZCULW2 (ORCPT ); Sat, 21 Mar 2009 07:22:28 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:41134 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752821AbZCULW1 (ORCPT ); Sat, 21 Mar 2009 07:22:27 -0400 Date: Sat, 21 Mar 2009 04:13:16 -0700 From: Andrew Morton To: Masami Hiramatsu Cc: Ingo Molnar , Steven Rostedt , Ananth N Mavinakayanahalli , Frederic Weisbecker , LKML , systemtap-ml Subject: Re: [RFC][PATCH -tip 0/5 V2] tracing: kprobe-based event tracer Message-Id: <20090321041316.562e7a0f.akpm@linux-foundation.org> In-Reply-To: <49C443E1.6070400@redhat.com> References: <49C443E1.6070400@redhat.com> X-Mailer: Sylpheed 2.4.7 (GTK+ 2.12.1; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1680 Lines: 35 On Fri, 20 Mar 2009 21:33:21 -0400 Masami Hiramatsu wrote: > echo /debug/tracing/trace Should be cat, I assume? > # tracer: nop > # > # TASK-PID CPU# TIMESTAMP FUNCTION > # | | | | | > <...>-2376 [001] 262.389131: do_sys_open: @do_sys_open+0 0xffffff9c 0x98db83e 0x8880 0x0 > <...>-2376 [001] 262.391166: sys_open: <-do_sys_open+0 0x5 0xc06e8ebb > <...>-2376 [001] 264.384876: do_sys_open: @do_sys_open+0 0xffffff9c 0x98db83e 0x8880 0x0 > <...>-2376 [001] 264.386880: sys_open: <-do_sys_open+0 0x5 0xc06e8ebb > <...>-2084 [001] 265.380330: do_sys_open: @do_sys_open+0 0xffffff9c 0x804be3e 0x0 0x1b6 > <...>-2084 [001] 265.380399: sys_open: <-do_sys_open+0 0x3 0xc06e8ebb Well... this is cool and all that, but nowhere near as useful as kgdb! Its main competition however will be plain old printk. Do we really honestly think that this feature will be sufficiently useful to a sufficiently large number of kernel developers as to warrant inclusion? Perhaps a bit more thought about some more complex use cases would help. And given that the users of this (and other tracing features) are general kernel developers rather than tracing (or kprobes) developers, it would be nice to get some feedback and even testing/usage results from those people. ie: everyone else. -- 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/