Re: Ftrace doesn't work anymore on latest tip

From: Frédéric Weisbecker
Date: Tue Oct 28 2008 - 05:02:24 EST


2008/10/28 Frédéric Weisbecker <fweisbec@xxxxxxxxx>:
> 2008/10/28 Steven Rostedt <rostedt@xxxxxxxxxxx>:
>>
>> On Tue, 28 Oct 2008, Fr?d?ric Weisbecker wrote:
>>
>>> Hi,
>>>
>>> I tried to launch the function tracer with the latest -tip.
>>> With DYNAMIC_FTRACE (I just tried one time), I set "function" to
>>> current_trace and it blocks during writing. I can't
>>> even switch to another console.
>>> Without DYNAMIC_FTRACE I can set the tracer to function but it doesn't
>>> produce any trace, even on trace or tracing_pipe.
>>>
>>> My config is in attachment.
>>> I will try some revert...or some other tracers.
>>>
>>
>>
>> You might want to update your config (make oldconfig?) The latest tip has
>> FUNCTION_TRACER instead of FTRACE.
>>
>> Also, the config you sent me, does not even have FTRACE on :-/
>>
>> CONFIG_HAVE_FTRACE=y
>> CONFIG_HAVE_DYNAMIC_FTRACE=y
>> CONFIG_HAVE_FTRACE_MCOUNT_RECORD=y
>> CONFIG_TRACER_MAX_TRACE=y
>> CONFIG_RING_BUFFER=y
>> CONFIG_TRACING=y
>> # CONFIG_FTRACE is not set
>> # CONFIG_IRQSOFF_TRACER is not set
>> # CONFIG_PREEMPT_TRACER is not set
>> # CONFIG_SYSPROF_TRACER is not set
>> CONFIG_SCHED_TRACER=y
>> CONFIG_CONTEXT_SWITCH_TRACER=y
>
> Sorry I sent a config for the mainline.
> This new one is the right.
>

One other point: I can't assign the sched_switch tracer.
echo sched_switch > current_tracer returns -EINVAL with
CONFIG_DYNAMIC_FTRACE disabled (didn't tested with enabled).

I will check that more deeper when I'll have more time.
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