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From: Derrick Stolee <stolee@gmail.com>
To: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH 6/9] trace2: add timer events to perf and event target formats
Date: Tue, 21 Dec 2021 09:20:26 -0500	[thread overview]
Message-ID: <8f62bae5-0026-c2c8-baa0-fd50b8d1668c@gmail.com> (raw)
In-Reply-To: <c5d5ff05e6ca5729993133ce0b6b94af2503808a.1640012469.git.gitgitgadget@gmail.com>

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

  parent reply	other threads:[~2021-12-21 14:20 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-20 15:01 [PATCH 0/9] Trace2 stopwatch timers and global counters Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 1/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 2/9] trace2: convert tr2tls_thread_ctx.thread_name from strbuf to char* Jeff Hostetler via GitGitGadget
2021-12-20 16:31   ` Ævar Arnfjörð Bjarmason
2021-12-20 19:07     ` Jeff Hostetler
2021-12-20 19:35       ` Ævar Arnfjörð Bjarmason
2021-12-22 16:32         ` Jeff Hostetler
2021-12-21  7:33     ` Junio C Hamano
2021-12-21  7:22   ` Junio C Hamano
2021-12-22 16:28     ` Jeff Hostetler
2021-12-22 19:57       ` Junio C Hamano
2021-12-20 15:01 ` [PATCH 3/9] trace2: defer free of TLS CTX until program exit Jeff Hostetler via GitGitGadget
2021-12-21  7:30   ` Junio C Hamano
2021-12-22 21:59     ` Jeff Hostetler
2021-12-22 22:56       ` Junio C Hamano
2021-12-22 23:04         ` Jeff Hostetler
2021-12-23  7:38         ` Johannes Sixt
2021-12-23 18:18           ` Junio C Hamano
2021-12-27 18:51             ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 4/9] trace2: add thread-name override to event target Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 5/9] trace2: add thread-name override to perf target Jeff Hostetler via GitGitGadget
2021-12-20 15:01 ` [PATCH 6/9] trace2: add timer events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-20 16:39   ` Ævar Arnfjörð Bjarmason
2021-12-20 19:44     ` Jeff Hostetler
2021-12-21 14:20   ` Derrick Stolee [this message]
2021-12-20 15:01 ` [PATCH 7/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2021-12-20 16:42   ` Ævar Arnfjörð Bjarmason
2021-12-22 21:38     ` Jeff Hostetler
2021-12-21 14:45   ` Derrick Stolee
2021-12-22 21:57     ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 8/9] trace2: add counter events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-20 16:51   ` Ævar Arnfjörð Bjarmason
2021-12-22 22:56     ` Jeff Hostetler
2021-12-20 15:01 ` [PATCH 9/9] trace2: add global counters Jeff Hostetler via GitGitGadget
2021-12-20 17:14   ` Ævar Arnfjörð Bjarmason
2021-12-22 22:18     ` Jeff Hostetler
2021-12-21 14:51 ` [PATCH 0/9] Trace2 stopwatch timers and " Derrick Stolee
2021-12-21 23:27   ` Matheus Tavares
2021-12-28 19:36 ` [PATCH v2 " Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 1/9] trace2: use size_t alloc,nr_open_regions in tr2tls_thread_ctx Jeff Hostetler via GitGitGadget
2021-12-29  0:48     ` Ævar Arnfjörð Bjarmason
2021-12-28 19:36   ` [PATCH v2 2/9] trace2: convert tr2tls_thread_ctx.thread_name from strbuf to flex array Jeff Hostetler via GitGitGadget
2021-12-29  1:11     ` Ævar Arnfjörð Bjarmason
2021-12-29 16:46       ` Jeff Hostetler
2021-12-28 19:36   ` [PATCH v2 3/9] trace2: defer free of thread local storage until program exit Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 4/9] trace2: add thread-name override to event target Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 5/9] trace2: add thread-name override to perf target Jeff Hostetler via GitGitGadget
2021-12-29  1:48     ` Ævar Arnfjörð Bjarmason
2021-12-29 17:15       ` Jeff Hostetler
2021-12-28 19:36   ` [PATCH v2 6/9] trace2: add timer events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 7/9] trace2: add stopwatch timers Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 8/9] trace2: add counter events to perf and event target formats Jeff Hostetler via GitGitGadget
2021-12-28 19:36   ` [PATCH v2 9/9] trace2: add global counters Jeff Hostetler via GitGitGadget
2021-12-29  1:54   ` [PATCH v2 0/9] Trace2 stopwatch timers and " Ævar Arnfjörð Bjarmason
2021-12-30 16:42     ` Jeff Hostetler

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