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Message-ID: <20090225141948.GA3123@redhat.com>
Date: Wed, 25 Feb 2009 09:19:49 -0500
From: Jason Baron <jbaron@...hat.com>
To: "Frank Ch. Eigler" <fche@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Theodore Tso <tytso@....edu>,
Arjan van de Ven <arjan@...radead.org>,
Pekka Paalanen <pq@....fi>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Martin Bligh <mbligh@...gle.com>,
Mathieu Desnoyers <compudj@...stal.dyndns.org>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Jens Axboe <jens.axboe@...cle.com>,
Masami Hiramatsu <mhiramat@...hat.com>
Subject: Re: [PATCH 0/4][RFC] event tracer
On Tue, Feb 24, 2009 at 09:10:33PM -0500, Frank Ch. Eigler wrote:
> Hi -
>
> > This is still RFC, do not pull.
> > This patch set gives the ability to add a format string and args to
> > a trace point declaration. [...]
>
> It looks like a good compromise, a dual to the trace_mark_tp
> prototype, and a plausible replacement for markers. Thank you. The
> main thing this would lose is a callback API to intercept generic
> varargs event flavour, which we in systemtap land enjoy using, but
> before too long we would make do.
>
Along these lines, I think it should be possible to have
'DEFINE_TRACE_FMT' define an additional tracepoint with a
signature that is simply a fomat string and a list of args. This
tracpoint is then what could be registred with the original tracepoint.
Then, event_trace_printk can be registered with this additional
tracepoint. In this way different consumers would be able to register
not only with the oringal tracepoint, but also with a format string
callback version of it. this obviously adds extra functions call, but at
the advantage of additional flexibility. If ppl think this makes sense,
I can prototype a patch.
thanks,
-Jason
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