[rtc-linux] Re: [PATCH 2/2] time: alarmtimer: Add the trcepoints for alarmtimer

On Wed, 21 Sep 2016, Baolin Wang wrote:

On 21 September 2016 at 06:27, Thomas Gleixner [off-list ref] wrote:

quoted

quoted

+     TP_fast_assign(
+             __entry->second = rtc_time->tm_sec;
+             __entry->minute = rtc_time->tm_min;
+             __entry->hour = rtc_time->tm_hour;
+             __entry->day = rtc_time->tm_mday;
+             __entry->mon = rtc_time->tm_mon;
+             __entry->year = rtc_time->tm_year;
+             __entry->alarm_type = flag;

What's the value of storing the alarm time in RTC format?

As suggested by Steven, change the type of RTC value to save trace buffer.

A single u64 does not take more storage space than this and it's a single
store.
 

quoted

2) You store the expiry time again in RTC format. Store the information in
   a plain u64 and be done with it.

But I still think the RTC format is more readable for debugging alarm timer.

That's what post processing is for.
 

quoted

What's the point of this conditional? Avoiding rtc_ktime_to_tm() ? Oh well...

quoted

+             tm_set = rtc_ktime_to_tm(now);
+             trace_alarmtimer_suspend(&tm_set, type);

"now" is CLOCK_REALTIME based. You store the type of the alarm timer which
is the first to expire and therefor is the one setting the RTC value, but
we don't know which timer it is. Useful - NOT!

We can know the timer by comparing the expire time.

Please make it similar to the timer/hrtimer tracing so people can reuse
their postprocessing scripts with minimial tweaks.

Thanks,

	tglx

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