Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759794AbZCPShy (ORCPT ); Mon, 16 Mar 2009 14:37:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753519AbZCPShp (ORCPT ); Mon, 16 Mar 2009 14:37:45 -0400 Received: from tomts13-srv.bellnexxia.net ([209.226.175.34]:57010 "EHLO tomts13-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753118AbZCPSho (ORCPT ); Mon, 16 Mar 2009 14:37:44 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AtsEAO84vklMQW1W/2dsb2JhbACBTtREg38G Date: Mon, 16 Mar 2009 14:37:39 -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: <20090316183739.GA10292@Krystal> References: <20090312183603.GC3352@redhat.com> <20090314025701.GC22526@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: 14:34:37 up 16 days, 15:00, 2 users, load average: 0.41, 0.70, 0.75 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: 2502 Lines: 66 * Steven Rostedt (rostedt@goodmis.org) wrote: > > On Fri, 13 Mar 2009, Mathieu Desnoyers wrote: > > > * Jason Baron (jbaron@redhat.com) wrote: > > > > > > introduce softirq entry/exit tracepoints. These are useful for > > > augmenting existing tracers, and to figure out softirq frequencies and > > > timings. > > > > > > Signed-off-by: Jason Baron > > > > > > --- > > > > > > include/trace/irq_event_types.h | 12 ++++++++++++ > > > kernel/softirq.c | 7 ++++++- > > > 2 files changed, 18 insertions(+), 1 deletions(-) > > > > > > > > > diff --git a/include/trace/irq_event_types.h b/include/trace/irq_event_types.h > > > index 214bb92..38b4bdd 100644 > > > --- a/include/trace/irq_event_types.h > > > +++ b/include/trace/irq_event_types.h > > > @@ -40,4 +40,16 @@ TRACE_EVENT(irq_handler_exit, > > > __entry->irq, __entry->ret ? "handled" : "unhandled") > > > ); > > > > > > +TRACE_FORMAT(irq_softirq_entry, > > > + TP_PROTO(struct softirq_action *h, struct softirq_action *vec), > > > + TP_ARGS(h, vec), > > > + TP_FMT("softirq=%d action=%s", h - vec, softirq_to_name[h-vec]) > > > + ); > > > + > > > +TRACE_FORMAT(irq_softirq_exit, > > > + TP_PROTO(struct softirq_action *h, struct softirq_action *vec), > > > + TP_ARGS(h, vec), > > > + TP_FMT("softirq=%d action=%s", h - vec, softirq_to_name[h-vec]) > > > > 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. 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/