Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761277AbZCPT2c (ORCPT ); Mon, 16 Mar 2009 15:28:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753519AbZCPT2X (ORCPT ); Mon, 16 Mar 2009 15:28:23 -0400 Received: from tomts43-srv.bellnexxia.net ([209.226.175.110]:39387 "EHLO tomts43-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753830AbZCPT2W (ORCPT ); Mon, 16 Mar 2009 15:28:22 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AtsEAONEvklMQW1W/2dsb2JhbACBTtNTg38G Date: Mon, 16 Mar 2009 15:28:17 -0400 From: Mathieu Desnoyers To: Steven Rostedt Cc: Jason Baron , mingo@elte.hu, linux-kernel@vger.kernel.org, acme@ghostprotocols.net, fweisbec@gmail.com, fche@redhat.com, peterz@infradead.org Subject: Re: [Patch 2/2] tracepoints for softirq entry/exit - tracepoints Message-ID: <20090316192817.GC11878@Krystal> References: <20090312183603.GC3352@redhat.com> <20090314025701.GC22526@Krystal> <20090316183739.GA10292@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 15:24:28 up 16 days, 15:50, 3 users, load average: 0.20, 0.46, 0.58 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2405 Lines: 61 * Steven Rostedt (rostedt@goodmis.org) wrote: > > On Mon, 16 Mar 2009, Steven Rostedt wrote: > > > > > On Mon, 16 Mar 2009, Mathieu Desnoyers wrote: > > > > > > > > > > The softirq tracepoints are a good idea indeed (I have similar ones in > > > > > the LTTng tree). My main concern is about the fact that you output the > > > > > softirq name in plain text to the trace buffers. I would rather prefer > > > > > to save only the softirq (h-vec) into the trace and dump the mapping > > > > > (h-vec) to name only once, so we can save precious trace bytes. > > > > > > > > The TP_FMT is only used by those tracers that want to use it. Any tracer > > > > can still hook directly to the trace point and do what every they want. > > > > > > > > -- Steve > > > > > > > > > > By doing so, you are removing the ability to use the TP_FMT information > > > to perform high-speed system-wide tracing. I thought the goal was to > > > create a unified buffering, but sadly I don't see the high-speed > > > requirements being part of that plan. > > > > TP_FMT has nothing to do with the unified buffering. The unified buffer > > does not even know about it. But if you want high-speed event tracing, > > that is what the TRACE_EVENT was created for. > > Here's an example: > > The "event tracing" uses the format field to show those events for the > hook in the sched switching, and wake ups. > > The wake up tracer on the other hand, does not care about the format, it > only cares about having a hook where a a task is woken up, and where it > gets scheduled in, and perhaps events in between. But it uses its own > formatting to do the output. > > -- Steve > If I understand you correctly, the format string is only useful to the text-output tracer ? Why can't it be used to identify both text and binary events ? And remember that from my perspective, information is only useful if available for system-wide tracing. Specialized tracers come as a subset of system-wide tracing anyway when the latter is implemented with the proper hooks. Mathieu -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- 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/