linux-kernel - Re: [PATCH 4/4] perf tools: Complete support for dynamic strings

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Message-ID: <20090831165924.GA6048@nowhere>
Date:	Mon, 31 Aug 2009 18:59:26 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 4/4] perf tools: Complete support for dynamic strings

On Mon, Aug 31, 2009 at 10:11:33AM +0200, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@...il.com> wrote:
> 
> > Complete support for __str_loc type strings of ftrace events which
> > have dynamic offsets values set for each of them inside their sammples.
> > 
> > Before:
> >         geany-5759  [000]     0.000000: lock_release: name
> >         geany-5759  [000]     0.000000: lock_release: name
> >         geany-5759  [000]     0.000000: lock_release: name
> >   kondemand/0-362   [000]     0.000000: lock_release: name
> >       pdflush-421   [000]     0.000000: lock_release: name
> > 
> > After:
> >         geany-5759  [000]     0.000000: lock_release: &u->lock
> >         geany-5759  [000]     0.000000: lock_release: key
> >         geany-5759  [000]     0.000000: lock_release: &group->notification_mutex
> >   kondemand/0-362   [000]     0.000000: lock_release: &rq->lock
> >       pdflush-421   [000]     0.000000: lock_release: &rq->lock
> 
> I've applied all five patches, thanks Frederic!
> 
> Also, i think this makes perf trace quite functional already so i 
> merged that topic (and these commits) into tracing/core, for v2.6.32 
> merging.



Ok.


 
> One thing that i noticed which is still quite quirky are the 
> parameters to perf record. (needing -R and the :r postfix to events) 
> Could something more intuitive be done here?


I hope. It's not that easy, at least for me, to find something intuitive
there.

I've thought about

  -e *sys:event  (because the * suggests a deref that takes the content)
                 But that's a bit convoluted. And moreover we may want
                 to support basic regex later for event selection.

If someone has an idea, please tell me.

Another thing. We could, by default display a small comment while
selecting an event without its content:

"Opening counter sys:event. Type -R if you want raw sampling."

The user could shut that up with a -q option.

> Also, i think people would like to use wildcards in event 
> specifiers, such as:
> 
>   perf record -e timer/*
> 
> To capture all timer events:
> 
>  hrtimer_cancel
>  hrtimer_expire_entry
>  hrtimer_expire_exit
>  hrtimer_init
>  hrtimer_start
>  itimer_expire
>  itimer_state
>  timer_cancel
>  timer_expire_entry
>  timer_expire_exit
>  timer_init
>  timer_start
>
> Instead of having to type:
> 
> perf record -e hrtimer_cancel -e hrtimer_expire_entry \
>  -e hrtimer_expire_exit -e hrtimer_init -e hrtimer_start \
>  -e itimer_expire -e itimer_state -e timer_cancel \
>  -e timer_expire_entry -e timer_expire_exit -e timer_init \
>  -e timer_start
> 
> which is not quite realistic.


Totally agreed, it was in my todo list.

But don't you think
	perf record -e timer:*
is more intuitive and follows the current logic?

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