linux-kernel - Re: [RFC PATCH 03/10] ftrace: Drop the ftrace_profile

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Date:	Thu, 21 Jan 2010 23:52:46 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Masami Hiramatsu <mhiramat@...hat.com>
Subject: Re: [RFC PATCH 03/10] ftrace: Drop the ftrace_profile_enabled
 checks in tracing hot path

On Thu, 2010-01-21 at 23:09 -0500, Mathieu Desnoyers wrote:
> * Steven Rostedt (rostedt@...dmis.org) wrote:

> > Hmm, interesting. Maybe something like that might work. But what if
> > CONFIG_PREEMPT is enabled but CONFIG_FREEZER is not?
> 
> Then you may want to make the function tracer depend on CONFIG_FREEZER,
> but maybe Masami has other ideas ?

egad no! This is just to help add guarantees to those that use the
function tracer that when the tracing is disabled, it is guaranteed that
no more tracing will be called by the function tracer. Currently,
nothing relies on this. But we may add cases that might need this.

In fact, only those that need this requirement would need to do this
trick. Anyway, we could make those depend on CONFIG_FREEZER, but that
just seems to be a strange dependency.

-- Steve


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