Re: [PATCH 09/10] time_stats: report information in json format

From: Darrick J. Wong
Date: Sat Feb 24 2024 - 01:02:59 EST

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In reply to: Kent Overstreet: "Re: [PATCH 09/10] time_stats: report information in json format"
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On Sat, Feb 24, 2024 at 12:10:33AM -0500, Kent Overstreet wrote:
> On Fri, Feb 23, 2024 at 08:15:45PM -0800, Darrick J. Wong wrote:
> > On Fri, Feb 23, 2024 at 05:12:26PM -0800, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <djwong@xxxxxxxxxx>
> > >
> > > Export json versions of time statistics information. Given the tabular
> > > nature of the numbers exposed, this will make it a lot easier for higher
> > > (than C) level languages (e.g. python) to import information without
> > > needing to write yet another clumsy string parser.
> > >
> > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> > > Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> > > ---
> > > include/linux/time_stats.h | 2 +
> > > lib/time_stats.c | 87 ++++++++++++++++++++++++++++++++++++++++++++
> > > 2 files changed, 89 insertions(+)
> > >
> > >
> > > diff --git a/include/linux/time_stats.h b/include/linux/time_stats.h
> > > index b3c810fff963a..4e1f5485ed039 100644
> > > --- a/include/linux/time_stats.h
> > > +++ b/include/linux/time_stats.h
> > > @@ -156,6 +156,8 @@ static inline bool track_event_change(struct time_stats *stats, bool v)
> > > struct seq_buf;
> > > void time_stats_to_seq_buf(struct seq_buf *, struct time_stats *,
> > > const char *epoch_name, unsigned int flags);
> > > +void time_stats_to_json(struct seq_buf *, struct time_stats *,
> > > + const char *epoch_name, unsigned int flags);
> > >
> > > void time_stats_exit(struct time_stats *);
> > > void time_stats_init(struct time_stats *);
> > > diff --git a/lib/time_stats.c b/lib/time_stats.c
> > > index 0fb3d854e503b..c0f209dd9f6dd 100644
> > > --- a/lib/time_stats.c
> > > +++ b/lib/time_stats.c
> > > @@ -266,6 +266,93 @@ void time_stats_to_seq_buf(struct seq_buf *out, struct time_stats *stats,
> > > }
> > > EXPORT_SYMBOL_GPL(time_stats_to_seq_buf);
> > >
> > > +void time_stats_to_json(struct seq_buf *out, struct time_stats *stats,
> > > + const char *epoch_name, unsigned int flags)
> > > +{
> > > + struct quantiles *quantiles = time_stats_to_quantiles(stats);
> > > + s64 f_mean = 0, d_mean = 0;
> > > + u64 f_stddev = 0, d_stddev = 0;
> > > +
> > > + if (stats->buffer) {
> > > + int cpu;
> > > +
> > > + spin_lock_irq(&stats->lock);
> > > + for_each_possible_cpu(cpu)
> > > + __time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
> > > + spin_unlock_irq(&stats->lock);
> > > + }
> > > +
> > > + if (stats->freq_stats.n) {
> > > + /* avoid divide by zero */
> > > + f_mean = mean_and_variance_get_mean(stats->freq_stats);
> > > + f_stddev = mean_and_variance_get_stddev(stats->freq_stats);
> > > + d_mean = mean_and_variance_get_mean(stats->duration_stats);
> > > + d_stddev = mean_and_variance_get_stddev(stats->duration_stats);
> > > + } else if (flags & TIME_STATS_PRINT_NO_ZEROES) {
> > > + /* unless we didn't want zeroes anyway */
> > > + return;
> > > + }
> > > +
> > > + seq_buf_printf(out, "{\n");
> > > + seq_buf_printf(out, " \"epoch\": \"%s\",\n", epoch_name);
> > > + seq_buf_printf(out, " \"count\": %llu,\n", stats->duration_stats.n);
> > > +
> > > + seq_buf_printf(out, " \"duration_ns\": {\n");
> > > + seq_buf_printf(out, " \"min\": %llu,\n", stats->min_duration);
> > > + seq_buf_printf(out, " \"max\": %llu,\n", stats->max_duration);
> > > + seq_buf_printf(out, " \"total\": %llu,\n", stats->total_duration);
> > > + seq_buf_printf(out, " \"mean\": %llu,\n", d_mean);
> > > + seq_buf_printf(out, " \"stddev\": %llu\n", d_stddev);
> > > + seq_buf_printf(out, " },\n");
> > > +
> > > + d_mean = mean_and_variance_weighted_get_mean(stats->duration_stats_weighted, TIME_STATS_MV_WEIGHT);
> > > + d_stddev = mean_and_variance_weighted_get_stddev(stats->duration_stats_weighted, TIME_STATS_MV_WEIGHT);
> > > +
> > > + seq_buf_printf(out, " \"duration_ewma_ns\": {\n");
> > > + seq_buf_printf(out, " \"mean\": %llu,\n", d_mean);
> > > + seq_buf_printf(out, " \"stddev\": %llu\n", d_stddev);
> > > + seq_buf_printf(out, " },\n");
> > > +
> > > + seq_buf_printf(out, " \"frequency_ns\": {\n");
> >
> > I took the variable names too literally here; these labels really ought
> > to be "between_ns" and "between_ewma_ns" to maintain consistency with
> > the labels in the table format.
> >
> > > + seq_buf_printf(out, " \"min\": %llu,\n", stats->min_freq);
> > > + seq_buf_printf(out, " \"max\": %llu,\n", stats->max_freq);
> > > + seq_buf_printf(out, " \"mean\": %llu,\n", f_mean);
> > > + seq_buf_printf(out, " \"stddev\": %llu\n", f_stddev);
> > > + seq_buf_printf(out, " },\n");
> > > +
> > > + f_mean = mean_and_variance_weighted_get_mean(stats->freq_stats_weighted, TIME_STATS_MV_WEIGHT);
> > > + f_stddev = mean_and_variance_weighted_get_stddev(stats->freq_stats_weighted, TIME_STATS_MV_WEIGHT);
> > > +
> > > + seq_buf_printf(out, " \"frequency_ewma_ns\": {\n");
> > > + seq_buf_printf(out, " \"mean\": %llu,\n", f_mean);
> > > + seq_buf_printf(out, " \"stddev\": %llu\n", f_stddev);
> > > +
> > > + if (quantiles) {
> > > + u64 last_q = 0;
> > > +
> > > + /* close frequency_ewma_ns but signal more items */
> >
> > (also this comment)
> >
> > > + seq_buf_printf(out, " },\n");
> > > +
> > > + seq_buf_printf(out, " \"quantiles_ns\": [\n");
> > > + eytzinger0_for_each(i, NR_QUANTILES) {
> > > + bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
> > > +
> > > + u64 q = max(quantiles->entries[i].m, last_q);
> > > + seq_buf_printf(out, " %llu", q);
> > > + if (!is_last)
> > > + seq_buf_printf(out, ", ");
> > > + last_q = q;
> > > + }
> > > + seq_buf_printf(out, " ]\n");
> > > + } else {
> > > + /* close frequency_ewma_ns without dumping further */
> >
> > (this one too)
> >
> > Kent, would you mind making that edit the next time you reflow your
> > branch?
> >
> > --D
> >
> > > + seq_buf_printf(out, " }\n");
> > > + }
> > > +
> > > + seq_buf_printf(out, "}\n");
> > > +}
> > > +EXPORT_SYMBOL_GPL(time_stats_to_json);
> > > +
> > > void time_stats_exit(struct time_stats *stats)
> > > {
> > > free_percpu(stats->buffer);
> > >
> > >
>
>
> From 5885a65fa5a0aace7bdf1a8fa58ac2bca3b15900 Mon Sep 17 00:00:00 2001
> From: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> Date: Sat, 24 Feb 2024 00:10:06 -0500
> Subject: [PATCH] fixup! time_stats: report information in json format
>
>
> diff --git a/lib/time_stats.c b/lib/time_stats.c
> index 0b90c80cba9f..d7dd64baebb8 100644
> --- a/lib/time_stats.c
> +++ b/lib/time_stats.c
> @@ -313,7 +313,7 @@ void time_stats_to_json(struct seq_buf *out, struct time_stats *stats,
> seq_buf_printf(out, " \"stddev\": %llu\n", d_stddev);
> seq_buf_printf(out, " },\n");
>
> - seq_buf_printf(out, " \"frequency_ns\": {\n");
> + seq_buf_printf(out, " \"between_ns\": {\n");
> seq_buf_printf(out, " \"min\": %llu,\n", stats->min_freq);
> seq_buf_printf(out, " \"max\": %llu,\n", stats->max_freq);
> seq_buf_printf(out, " \"mean\": %llu,\n", f_mean);
> @@ -323,14 +323,14 @@ void time_stats_to_json(struct seq_buf *out, struct time_stats *stats,
> f_mean = mean_and_variance_weighted_get_mean(stats->freq_stats_weighted, TIME_STATS_MV_WEIGHT);
> f_stddev = mean_and_variance_weighted_get_stddev(stats->freq_stats_weighted, TIME_STATS_MV_WEIGHT);
>
> - seq_buf_printf(out, " \"frequency_ewma_ns\": {\n");
> + seq_buf_printf(out, " \"between_ewma_ns\": {\n");

Looks good to me,
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>

--D

> seq_buf_printf(out, " \"mean\": %llu,\n", f_mean);
> seq_buf_printf(out, " \"stddev\": %llu\n", f_stddev);
>
> if (quantiles) {
> u64 last_q = 0;
>
> - /* close frequency_ewma_ns but signal more items */
> + /* close between_ewma_ns but signal more items */
> seq_buf_printf(out, " },\n");
>
> seq_buf_printf(out, " \"quantiles_ns\": [\n");
> @@ -345,7 +345,7 @@ void time_stats_to_json(struct seq_buf *out, struct time_stats *stats,
> }
> seq_buf_printf(out, " ]\n");
> } else {
> - /* close frequency_ewma_ns without dumping further */
> + /* close between_ewma_ns without dumping further */
> seq_buf_printf(out, " }\n");
> }
>

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In reply to: Kent Overstreet: "Re: [PATCH 09/10] time_stats: report information in json format"
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