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From: Steven Rostedt <>
To: Ingo Molnar <>
Cc: Zdenek Kabelac <>,
	Linux Kernel Mailing List <>,
	Peter Zijlstra <>
Subject: Re: sys_sched_yield keeps locked irq before call of schedule()
Date: Thu, 6 Nov 2008 09:46:57 -0500 (EST)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, 6 Nov 2008, Ingo Molnar wrote:
> > 
> > Quick note. Currently ftrace_printk only shows up if it is set in the 
> > iter_ctrl.
> > 
> >   echo trace_printk > /debug/tracing/iter_ctrl
> > 
> > I'll send out a patch to have it on by default.
> ok, agreed - but in that case please make the NOP tracer 
> tracing_enabled=0 by default. (we'll get a lot of ftrace_printk 
> tracepoints by default otherwise)

Hmm, I think it may be good to leave it on even for the nop tracer.

ftrace_printk's should not be out in open code unless someone is actually 
debugging it. You can use ftrace_printk inside a tracer to write stuff, 
but that printk should be protected somehow by the encompassing tracer.


	some_tracer(void) {
		if (!tracer_enabled)
		ftrace_printk("my special stuff\n");

I would think if someone is debugging their code by using ftrace_printk, 
they probably want it to show up right away, without having to remember to 
do a...

	echo trace_printk > /debug/tracing/iter_ctrl

And still have it show up in the nop tracer.

-- Steve

      reply	other threads:[~2008-11-06 14:47 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-05 12:57 Zdenek Kabelac
2008-11-05 13:01 ` Ingo Molnar
2008-11-05 13:09   ` Zdenek Kabelac
2008-11-05 14:05     ` Arnd Bergmann
2008-11-05 14:37       ` Zdenek Kabelac
2008-11-06  7:57     ` Ingo Molnar
2008-11-06 13:46       ` Steven Rostedt
2008-11-06 14:34         ` Ingo Molnar
2008-11-06 14:46           ` Steven Rostedt [this message]

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