Re: wakeup tracer not able to capture traces on 3.4 kernel

From: Prabhat Kumar Ravi
Date: Thu Aug 29 2013 - 11:12:14 EST


On Thu, Aug 29, 2013 at 7:41 PM, Prabhat Kumar Ravi
<prabhatravi09@xxxxxxxxx> wrote:
> Hi,
>
> I trying to capture traces through wakeup tracer, but not able to
> capture it on 3.4 kernel with cortex A9 processor, armv7.
> {{{
> / # mount -t debugfs nodev /debug
> / # sysctl kernel.ftrace_enabled=1
> kernel.ftrace_enabled = 1
> / # echo wakeup > /debug/tracing/current_tracer
> / # echo latency-format > /debug/tracing/trace_options
> / # echo 0 > /debug/tracing/tracing_max_latency
> / # echo 1 > /debug/tracing/tracing_on
> / # sleep 10
> / # echo 0 > /debug/tracing/tracing_on
> / # cat /debug/tracing/trace
> # tracer: wakeup
> #
> }}}

My target board is xilinx-zc702,
here in kernel/trace/trace.c:
void tracing_record_cmdline(struct task_struct *tsk)
{
if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
!tracing_is_on())
-------------------------------> it not coming here at all.
return;

trace_save_cmdline(tsk);
}

Regards,
Prabhat
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