Subject: Re: request to add trace off and trace on with events
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tim Bird <tim.bird@am.sony.com>, Tom Zanussi <tzanussi@gmail.com>,
       Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       Chase Douglas <chase.douglas@canonical.com>,
       LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <20100419220437.GC8811@nowhere>
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Organization: Kihon Technologies Inc.
Date: Mon, 19 Apr 2010 18:13:47 -0400
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On Tue, 2010-04-20 at 00:04 +0200, Frederic Weisbecker wrote:
> On Mon, Apr 19, 2010 at 05:37:54PM -0400, Steven Rostedt wrote:

> > # cat event/sched/sched_switch/triggers/tracing_off
> > disabled
> > 
> > Or it can be a filter, or enabled.
> 
> 
> Yep, since it would share exatly the same code than filter (as
> filter basically becomes a trigger command), it can behave the
> same: displaying "none" when there is no filter, or a filter.
> 

Then do we make the triggers themselves directories too?

# ls event/sched/sched_switch/triggers/tracing_off
filter   enable

?

> 
> > 
> > This could also allow a user to do:
> > 
> > echo "(a > 100)" > tracing_on
> > echo "(a < 100)" > tracing_off
> 
> 
> Yeah :)
> But if the scope of the "tracing off" is only for this event, then
> rather use:
> 
> echo "(a < 100)" > filter
> 
> You could have tracing_off/on that have this event scope and
> tracing_off/on_all for a global tracing scope.

The two are not equivalent. In fact, just enabling a trigger does not
mean that the event itself will be traced.

-- Steve


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