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Subject: Re: [PATCH v5 00/45] CPU hotplug: stop_machine()-free CPU hotplug
From: Steven Rostedt <rostedt@goodmis.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Date: Mon, 18 Feb 2013 14:53:15 -0500
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On Mon, 2013-02-18 at 17:50 +0100, Vincent Guittot wrote:

> yes for sure.
> The problem is more linked to cpuidle and function tracer.
> 
> cpu hotplug and function tracer work when cpuidle is disable.
> cpu hotplug and cpuidle works if i don't enable function tracer.
> my platform is dead as soon as I enable function tracer if cpuidle is
> enabled. It looks like some notrace are missing in my platform driver
> but we haven't completely fix the issue yet
> 

You can bisect to find out exactly what function is the problem:

 cat /debug/tracing/available_filter_functions > t
 
f(t) {
 num=`wc -l t`
 sed -ne "1,${num}p" t > t1
 let num=num+1
 sed -ne "${num},$p" t > t2

 cat t1 > /debug/tracing/set_ftrace_filter
 # note this may take a long time to finish

 echo function > /debug/tracing/current_tracer

 <failed? bisect f(t1), if not bisect f(t2)>
}