On 12/20/2021 10:01 AM, Jeff Hostetler via GitGitGadget wrote:
> +`"timer"`::
> + This event is generated at the end of the program and contains
> + statistics for a global stopwatch timer.
> ++
> +------------
> +{
> + "event":"timer",
> + ...
> + "name":"test", # timer name
> + "count":42, # number of start+stop intervals
> + "t_total":1.234, # sum of all intervals (by thread or globally)
> + "t_min":0.1, # shortest interval
> + "t_max":0.9, # longest interval
Could you specify the units for these t_* entries? I'm guessing seconds
based on the example, but I've seen similar timers using milliseconds
instead so it's best to be super clear here.
> +/*
> + * Stopwatch timer event. This function writes the previously accumlated
s/accumlated/accumulated/
> + * stopwatch timer values to the event streams. Unlike other Trace2 API
> + * events, this is decoupled from the data collection.
> + *
> + * This does not take a (file,line) pair because a timer event reports
> + * the cummulative time spend in the timer over a series of intervals
s/cummulative/cumulative/
> + * -- it does not represent a single usage (like region or data events
> + * do).
> + *
> + * The thread name is optional. If non-null it will override the
> + * value inherited from the caller's TLS CTX. This allows data
> + * for global timers to be reported without associating it with a
> + * single thread.
> + */
> +typedef void(tr2_tgt_evt_timer_t)(uint64_t us_elapsed_absolute,
> + const char *thread_name,
> + const char *category,
> + const char *timer_name,
> + uint64_t interval_count,
> + uint64_t us_total_time,
> + uint64_t us_min_time,
> + uint64_t us_max_time);
> diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
> index 4ce50944298..9b3905b920c 100644
> --- a/trace2/tr2_tgt_event.c
> +++ b/trace2/tr2_tgt_event.c
...
> +static void fn_timer(uint64_t us_elapsed_absolute,
(I was going to complain about the generic name here, but it's static
to the tr2_tgt_event.c file, so that's fine.)
> + const char *thread_name,
> + const char *category,
> + const char *timer_name,
> + uint64_t interval_count,
> + uint64_t us_total_time,
> + uint64_t us_min_time,
> + uint64_t us_max_time)
> +{
> + const char *event_name = "timer";
> + struct json_writer jw = JSON_WRITER_INIT;
> + double t_abs = (double)us_elapsed_absolute / 1000000.0;
> +
> + double t_total = (double)us_total_time / 1000000.0;
> + double t_min = (double)us_min_time / 1000000.0;
> + double t_max = (double)us_max_time / 1000000.0;
Looks like seconds here. At first glance, I thought this large division
might cause some loss of precision. However, the structure of floating
point numbers means we probably don't lose that much. It might be worth
_considering_ using milliseconds (only divide by 1000.0) but I'm
probably just being paranoid here.
Thanks,
-Stolee
