Re: [PATCH v3] time: alarmtimer: Add the trcepoints for alarmtimer

[Steven Rostedt]

On Tue, 11 Oct 2016 18:48:16 +0800
Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:

> For system debugging, we sometimes want to know who sets one
> alarm timer, the time of the timer, when the timer started and
> fired and so on. Thus adding tracepoints can help us trace the
> alarmtimer information.
> 
> For example, when we debug the system supend/resume, if the
> system is always resumed by RTC alarm, we can find out which
> process set the alarm timer to resume system by below trace log:
> 
> ......
> 
> Binder:3292_2-3304  [000] d..2   149.981123: alarmtimer_cancel:
> alarmtimer:ffffffc1319a7800 type:ALARM_REALTIME
> expires:1325463120000000000 now:1325376810370370245
> 
> Binder:3292_2-3304  [000] d..2   149.981136: alarmtimer_start:
> alarmtimer:ffffffc1319a7800 type:ALARM_REALTIME
> expires:1325376840000000000 now:1325376810370384591
> 
> Binder:3292_9-3953  [000] d..2   150.212991: alarmtimer_cancel:
> alarmtimer:ffffffc1319a5a00 type:ALARM_BOOTTIME
> expires:179552000000 now:150154008122
> 
> Binder:3292_9-3953  [000] d..2   150.213006: alarmtimer_start:
> alarmtimer:ffffffc1319a5a00 type:ALARM_BOOTTIME
> expires:179551000000 now:150154025622
> 
> ......
> 
> system_server-3000  [002] ...1  1087.737565: alarmtimer_suspend:
> alarmtimer type:ALARM_BOOTTIME expires: 1325376839802714584
> 
> ......
> 
> >From the trace log, we can find out the 'Binder:3292_2' process  
> set one alarm timer which resumes the system.
> 
> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
> ---
> Changes since v2:
>  - Save time as s64 type.
>  - Remove 'process_name' parameter and add 'now' parameter.
>  - Rename the trace event name.
>  - Remove restart trace event.
>  - Other optimization.
> ---
>  include/trace/events/alarmtimer.h |   92 +++++++++++++++++++++++++++++++++++++
>  kernel/time/alarmtimer.c          |   16 ++++++-
>  2 files changed, 106 insertions(+), 2 deletions(-)
>  create mode 100644 include/trace/events/alarmtimer.h
> 
> diff --git a/include/trace/events/alarmtimer.h b/include/trace/events/alarmtimer.h
> new file mode 100644
> index 0000000..4c92a3e
> --- /dev/null
> +++ b/include/trace/events/alarmtimer.h
> @@ -0,0 +1,92 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM alarmtimer
> +
> +#if !defined(_TRACE_ALARMTIMER_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_ALARMTIMER_H
> +
> +#include <linux/alarmtimer.h>
> +#include <linux/rtc.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_DEFINE_ENUM(ALARM_REALTIME);
> +TRACE_DEFINE_ENUM(ALARM_BOOTTIME);
> +
> +#define show_alarm_type(type)	__print_flags(type, " | ",	\
> +	{ 1 << ALARM_REALTIME, "ALARM_REALTIME" },		\
> +	{ 1 << ALARM_BOOTTIME, "ALARM_BOOTTIME" })

Why have the "ALARM_" prefix in the string? We already know that these
are "alarm" tracepoints. They just make the lines longer than they need
to be.

Other than that, from a tracing point of view, this looks fine to me.

Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

-- Steve


> +
> +TRACE_EVENT(alarmtimer_suspend,
> +
> +	TP_PROTO(ktime_t expires, int flag),
> +
> +	TP_ARGS(expires, flag),
> +
> +	TP_STRUCT__entry(
> +		__field(s64, expires)
> +		__field(unsigned char, alarm_type)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->expires = expires.tv64;
> +		__entry->alarm_type = flag;
> +	),
> +
> +	TP_printk("alarmtimer type:%s expires:%llu",
> +		  show_alarm_type((1 << __entry->alarm_type)),
> +		  __entry->expires
> +	)
> +);
> +
> +DECLARE_EVENT_CLASS(alarm_class,
> +
> +	TP_PROTO(struct alarm *alarm, ktime_t now),
> +
> +	TP_ARGS(alarm, now),
> +
> +	TP_STRUCT__entry(
> +		__field(void *,	alarm)
> +		__field(unsigned char, alarm_type)
> +		__field(s64, expires)
> +		__field(s64, now)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->alarm = alarm;
> +		__entry->alarm_type = alarm->type;
> +		__entry->expires = alarm->node.expires.tv64;
> +		__entry->now = now.tv64;
> +	),
> +
> +	TP_printk("alarmtimer:%p type:%s expires:%llu now:%llu",
> +		  __entry->alarm,
> +		  show_alarm_type((1 << __entry->alarm_type)),
> +		  __entry->expires,
> +		  __entry->now
> +	)
> +);
> +
> +DEFINE_EVENT(alarm_class, alarmtimer_fired,
> +
> +	TP_PROTO(struct alarm *alarm, ktime_t now),
> +
> +	TP_ARGS(alarm, now)
> +);
> +
> +DEFINE_EVENT(alarm_class, alarmtimer_start,
> +
> +	TP_PROTO(struct alarm *alarm, ktime_t now),
> +
> +	TP_ARGS(alarm, now)
> +);
> +
> +DEFINE_EVENT(alarm_class, alarmtimer_cancel,
> +
> +	TP_PROTO(struct alarm *alarm, ktime_t now),
> +
> +	TP_ARGS(alarm, now)
> +);
> +
> +#endif /* _TRACE_ALARMTIMER_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
> index c3aad68..4e10dad 100644
> --- a/kernel/time/alarmtimer.c
> +++ b/kernel/time/alarmtimer.c
> @@ -26,6 +26,9 @@
>  #include <linux/workqueue.h>
>  #include <linux/freezer.h>
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/alarmtimer.h>
> +
>  /**
>   * struct alarm_base - Alarm timer bases
>   * @lock:		Lock for syncrhonized access to the base
> @@ -194,6 +197,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
>  	}
>  	spin_unlock_irqrestore(&base->lock, flags);
>  
> +	trace_alarmtimer_fired(alarm, base->gettime());
>  	return ret;
>  
>  }
> @@ -222,7 +226,7 @@ static int alarmtimer_suspend(struct device *dev)
>  	ktime_t min, now;
>  	unsigned long flags;
>  	struct rtc_device *rtc;
> -	int i;
> +	int i, type = 0;
>  	int ret;
>  
>  	spin_lock_irqsave(&freezer_delta_lock, flags);
> @@ -247,8 +251,10 @@ static int alarmtimer_suspend(struct device *dev)
>  		if (!next)
>  			continue;
>  		delta = ktime_sub(next->expires, base->gettime());
> -		if (!min.tv64 || (delta.tv64 < min.tv64))
> +		if (!min.tv64 || (delta.tv64 < min.tv64)) {
>  			min = delta;
> +			type = i;
> +		}
>  	}
>  	if (min.tv64 == 0)
>  		return 0;
> @@ -264,6 +270,8 @@ static int alarmtimer_suspend(struct device *dev)
>  	now = rtc_tm_to_ktime(tm);
>  	now = ktime_add(now, min);
>  
> +	trace_alarmtimer_suspend(now, type);
> +
>  	/* Set alarm, if in the past reject suspend briefly to handle */
>  	ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
>  	if (ret < 0)
> @@ -342,6 +350,8 @@ void alarm_start(struct alarm *alarm, ktime_t start)
>  	alarmtimer_enqueue(base, alarm);
>  	hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
>  	spin_unlock_irqrestore(&base->lock, flags);
> +
> +	trace_alarmtimer_start(alarm, base->gettime());
>  }
>  EXPORT_SYMBOL_GPL(alarm_start);
>  
> @@ -390,6 +400,8 @@ int alarm_try_to_cancel(struct alarm *alarm)
>  	if (ret >= 0)
>  		alarmtimer_dequeue(base, alarm);
>  	spin_unlock_irqrestore(&base->lock, flags);
> +
> +	trace_alarmtimer_cancel(alarm, base->gettime());
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(alarm_try_to_cancel);