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Date: Thu, 18 Nov 2010 15:02:55 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
        Darren Hart <dvhart@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "jason.wessel" <jason.wessel@windriver.com>,
        "Ted Ts'o" <tytso@mit.edu>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [RFC][PATCH 0/2] tracing: Have trace_printk()s in the events/
	directory
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On Thu, Nov 18, 2010 at 08:06:36AM -0500, Steven Rostedt wrote:
> On Thu, 2010-11-18 at 13:53 +0100, Frederic Weisbecker wrote:
> > n other solution, which have been talking with Thomas yesterday, would be
> > to allow having a single fd for several perf_events at once. That would
> > solve some problems when you have hundreds of events opened (think about
> > wide tracing, or use of all individual syscalls).
> 
> I would highly recommend this. One type of tracing I do all the time is
> to enable all events (over 600). I don't think that is currently
> possible with trace and/or perf.


Yep.



> Ftrace has no issue simple because it just stores all the events into a
> single buffer (per cpu though). It does not care if there's one event or
> 1000.
> 
> You need to figure out how to do this as well with the function tracer.


Yeah for the function (and graph) tracers, I really plan to make it a single
event. I mean one for the function tracer and one for the function graph.
Although we may want two for the function graph tracer actually. One for
entry, one for exit.