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Message-ID: <20090224193952.GB27491@elte.hu>
Date: Tue, 24 Feb 2009 20:39:52 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org,
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>,
Jason Baron <jbaron@...hat.com>,
Martin Bligh <mbligh@...gle.com>,
Mathieu Desnoyers <compudj@...stal.dyndns.org>,
"Frank Ch. Eigler" <fche@...hat.com>,
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
* Steven Rostedt <rostedt@...dmis.org> wrote:
> 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. Then it gives a tracer an
> opportunity to override the header macro and use the default
> trace format to trace the object.
>
> For example (and used in this patch series), the sched
> tracepoint declarations are moved from include/trace/sched.h
> to include/trace/sched_event_types.h, and instead of using the
> macro DECLARE_TRACE we use DECLARE_TRACE_FMT. The first three
> arguments are the same, but it adds 2 more arguments. A printf
> format and arguments.
>
> The new trace/sched.h file contains:
>
> #include <linux/sched.h>
> #include <linux/tracepoint.h>
>
> #include <trace/sched_event_types.h>
>
> The sched_event_types.h file has:
>
> DECLARE_TRACE_FMT(sched_kthread_stop,
> TPPROTO(struct task_struct *t),
> TPARGS(t),
> "task %s:%d", TPARGS(t->comm, t->pid));
>
> The tracepoint.h defines DECLARE_TRACE_FMT as:
>
> #define DECLARE_TRACE_FMT(name, proto, args, fmt, fmt_args) \
> DECLARE_TRACE(name, TPPROTO(proto), TPARGS(args))
>
>
> But in kernel/trace/events.c we have:
>
> /* trace/<type>.h here */
> #include <trace/sched.h>
>
> #include "trace_events.h"
>
> /* trace/<type>_event_types.h here */
> #include <trace/sched_event_types.h>
>
> The trace_events.h redefines the DECLARE_TRACE_FMT and makes a
> hook for to automate adding event points.
>
> To add event points, convert to the DECLARE_TRACE_FMT, add
> your default printf format, and then add to events.c, the
> <type>.h and <type>_event_types.h as described. Then your
> trace points will appear in the event tracer.
>
> Next I'll convert the rest of the tracepoints that are already
> defined to this format.
Looks very good - especially the VFS enumeration of all present
tracepoints. Let me know when it gets into pullable state.
Ingo
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