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SubjectRe: [PATCH v2 1/2] ftrace: add tracepoint for timer
On Wed, Jun 17, 2009 at 05:39:19PM +0800, Xiao Guangrong wrote:
> This patch is modify from Mathieu's patch base on Ingo's suggestion, the
> original patch can be found here:
> http://marc.info/?l=linux-kernel&m=123791201816247&w=2
>
> Great thanks to Thomas for giving me so many valuable advices.
>
> Those tracepoints are wanted and useful:
> 1: We can detect a timer's delay
> 2: We can monitor the lifecycle and behaviors of a timer
>
> Thus they help in analysing and debuging.
>
> Example ftrace output:
> insmod-3743 [001] 217105.738770: timer_init: timer=e0b3e4c8
> insmod-3743 [001] 217105.738868: timer_start: timer=e0b3e4c8 func=timer_fun expires=442863 timeout=50
> <idle>-0 [001] 217105.935436: timer_expire: timer=e0b3e4c8 func=timer_fun jiffies=442863
> <idle>-0 [001] 217105.935440: timer_cancel: timer=e0b3e4c8 func=timer_fun
>
> We expect the timer expires at 442863, after 50 jiffies, actually the timer
> expires at 442863, so it is delayed by 0 jiffies.
>
> Changelog v1->v2:
> 1: Add jiffies info into timer
> 2: Combine debugobjects and trace as Thomas's suggestion
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>


Thomas, are you fine with these patches?
If so, I can prepare a pull request to Ingo, unless he prefers to
apply them himself.

Thanks,
Frederic.



> ---
> include/trace/events/timer.h | 82 ++++++++++++++++++++++++++++++++++++++++++
> kernel/timer.c | 33 +++++++++++++++--
> 2 files changed, 111 insertions(+), 4 deletions(-)
>
> diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
> index 6e7beb5..e9c51ee 100644
> --- a/include/trace/events/timer.h
> +++ b/include/trace/events/timer.h
> @@ -110,6 +110,88 @@ TRACE_EVENT(hrtimer_exit,
> "HRTIMER_RESTART" : "HRTIMER_NORESTART")
> );
>
> +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)
> +);
> +
> +TRACE_EVENT(timer_start,
> +
> + TP_PROTO(struct timer_list *timer, unsigned long expires),
> +
> + TP_ARGS(timer, expires),
> +
> + TP_STRUCT__entry(
> + __field( void *, timer )
> + __field( void *, function )
> + __field( unsigned long, expires )
> + __field( int, timeout )
> + ),
> +
> + TP_fast_assign(
> + __entry->timer = timer;
> + __entry->function = timer->function;
> + __entry->expires = expires;
> + __entry->timeout = timer->expires - jiffies;
> + ),
> +
> + TP_printk("timer=%p func=%pf expires=%lu timeout=%d", __entry->timer,
> + __entry->function, __entry->expires, __entry->timeout)
> +);
> +
> +TRACE_EVENT(timer_expire,
> +
> + TP_PROTO(struct timer_list *timer),
> +
> + TP_ARGS(timer),
> +
> + TP_STRUCT__entry(
> + __field( void *, timer )
> + __field( void *, function )
> + __field( unsigned long, jiffies )
> + ),
> +
> + TP_fast_assign(
> + __entry->timer = timer;
> + __entry->function = timer->function;
> + __entry->jiffies = jiffies;
> + ),
> +
> + TP_printk("timer=%p func=%pf jiffies=%lu", __entry->timer,
> + __entry->function, __entry->jiffies)
> +);
> +
> +TRACE_EVENT(timer_cancel,
> +
> + TP_PROTO(struct timer_list *timer),
> +
> + TP_ARGS(timer),
> +
> + TP_STRUCT__entry(
> + __field( void *, timer )
> + __field( void *, function )
> + ),
> +
> + TP_fast_assign(
> + __entry->timer = timer;
> + __entry->function = timer->function;
> + ),
> +
> + TP_printk("timer=%p func=%pf", __entry->timer, __entry->function)
> +);
> +
> #endif /* _TRACE_TIMER_H */
>
> /* This part must be outside protection */
> diff --git a/kernel/timer.c b/kernel/timer.c
> index d07c900..11660c7 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -521,6 +521,30 @@ static inline void debug_timer_activate(struct timer_list *timer) { }
> static inline void debug_timer_deactivate(struct timer_list *timer) { }
> #endif
>
> +static inline void debug_and_trace_timer_init(struct timer_list *timer)
> +{
> + debug_timer_init(timer);
> + trace_timer_init(timer);
> +}
> +
> +static inline void
> +debug_and_trace_timer_activate(struct timer_list *timer, unsigned long expires)
> +{
> + debug_timer_activate(timer);
> + trace_timer_start(timer, expires);
> +}
> +
> +static inline void debug_and_trace_timer_expire(struct timer_list *timer)
> +{
> + trace_timer_expire(timer);
> +}
> +
> +static inline void debug_and_trace_timer_deactivate(struct timer_list *timer)
> +{
> + debug_timer_deactivate(timer);
> + trace_timer_cancel(timer);
> +}
> +
> static void __init_timer(struct timer_list *timer,
> const char *name,
> struct lock_class_key *key)
> @@ -549,7 +573,7 @@ void init_timer_key(struct timer_list *timer,
> const char *name,
> struct lock_class_key *key)
> {
> - debug_timer_init(timer);
> + debug_and_trace_timer_init(timer);
> __init_timer(timer, name, key);
> }
> EXPORT_SYMBOL(init_timer_key);
> @@ -568,7 +592,7 @@ static inline void detach_timer(struct timer_list *timer,
> {
> struct list_head *entry = &timer->entry;
>
> - debug_timer_deactivate(timer);
> + debug_and_trace_timer_deactivate(timer);
>
> __list_del(entry->prev, entry->next);
> if (clear_pending)
> @@ -629,7 +653,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
> goto out_unlock;
> }
>
> - debug_timer_activate(timer);
> + debug_and_trace_timer_activate(timer, expires);
>
> new_base = __get_cpu_var(tvec_bases);
>
> @@ -781,7 +805,7 @@ void add_timer_on(struct timer_list *timer, int cpu)
> BUG_ON(timer_pending(timer) || !timer->function);
> spin_lock_irqsave(&base->lock, flags);
> timer_set_base(timer, base);
> - debug_timer_activate(timer);
> + debug_and_trace_timer_activate(timer, timer->expires);
> internal_add_timer(base, timer);
> /*
> * Check whether the other CPU is idle and needs to be
> @@ -952,6 +976,7 @@ static inline void __run_timers(struct tvec_base *base)
> unsigned long data;
>
> timer = list_first_entry(head, struct timer_list,entry);
> + debug_and_trace_timer_expire(timer);
> fn = timer->function;
> data = timer->data;
>
> --
> 1.6.1.2
>
>



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