Re: Re: [PATCH 1/3] ftrace: add tracepoint for timer
Date: Thu May 28 2009 - 22:02:30 EST
Thomas Gleixner wrote:
> On Wed, 27 May 2009, Xiao Guangrong wrote:
>>>> + TP_printk("timer=%p func=%pf expires=%lu cpu=%d", __entry->timer,
>>>> + __entry->function, __entry->expires, __entry->cpu)
>>> How do we connect the trace to the jiffies value when the timer
>>> was started ?
>> ftrace already have time information in trace event's output, we can use it instead
> Hmm, I'm not sure whether we can see the jiffies value there, but ok.
>>>> @@ -547,6 +550,7 @@ void init_timer_key(struct timer_list *timer,
>>>> __init_timer(timer, name, key);
>>>> + trace_timer_init(timer);
>>> Can we please avoid to have two debug calls in one 2 line function ?
>> debug_timer_init() must call before object's init, but tracepoint have to call
>> after object's init beacuse if we move the tracepoint to before object init, the
>> object has no data yet.
>>>> + TRACE_EVENT(timer_init,
>>>> + TP_PROTO(struct timer_list *timer),
>>>> + TP_ARGS(timer),
>>>> + TP_STRUCT__entry(
>>>> + __field( void *, timer )
>>>> + ),
>>>> + TP_fast_assign(
>>>> + __entry->timer = timer;
>>>> + ),
>>>> + TP_printk("timer=%p", __entry->timer)
> Is timer different before and after the __init_timer call ?
Yes, timer's pointer is same before and after __init_timer().
We don't need to put debug_timer_init() and trace_timer_init() into different
But, for trace_timer_start() in __mod_timer(), we need to put it after
Nevertheless, it don't means we need separate trace_timer_start() and
debug_timer_activate(), because we can put move debug_timer_activate() below,
timer->expires = expires;
+ trace_timer_start(timer, smp_processor_id());
Then we can also combine debug_timer_activate() and trace_timer_start() into
So we'll do what you suggested.
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