Re: Ftrace: can trace kthread?

[Yong Zhang]

On Thu, Oct 21, 2010 at 4:21 PM, Figo.zhang
<zhangtianfei@xxxxxxxxxxxxxxxx> wrote:
> On Thu, 2010-10-21 at 16:10 +0800, Yong Zhang wrote:
>> On Thu, Oct 21, 2010 at 3:55 PM, Figo.zhang
>> <zhangtianfei@xxxxxxxxxxxxxxxx> wrote:
>> > hi,
>> >
>> > is it ftrace in 2.6.36-rc8 can trace the kthread?
>>
>> How about the set_ftrace_pid interface?
>>
>
> i try by set_ftrace_pid, it also can't ftrace the kswapd.

Are you sure kswapd got chance to run on your system?

BTW, I can successfully trace bdi_writeback_thread,
# tracer: function
#
#           TASK-PID    CPU#    TIMESTAMP  FUNCTION
#              | |       |          |         |
       flush-8:0-374   [000] 600743.828496: finish_task_switch <-schedule
       flush-8:0-374   [000] 600743.828498: perf_event_task_sched_in
<-finish_task_switch
       flush-8:0-374   [000] 600743.828498: del_timer_sync <-schedule_timeout
       flush-8:0-374   [000] 600743.828499: try_to_del_timer_sync
<-del_timer_sync
       flush-8:0-374   [000] 600743.828499: lock_timer_base
<-try_to_del_timer_sync
       flush-8:0-374   [000] 600743.828499: _spin_lock_irqsave <-lock_timer_base
       flush-8:0-374   [000] 600743.828500: _spin_unlock_irqrestore
<-try_to_del_timer_sync
       flush-8:0-374   [000] 600743.828500: kthread_should_stop
<-bdi_writeback_task

Thanks,
Yong
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