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Date: Fri, 23 Feb 2024 17:09:49 -0800
Subject: [PATCH 3/4] bcachefs: bch2_time_stats_to_seq_buf()
From: "Darrick J. Wong" <djwong@kernel.org>
To: akpm@linux-foundation.org, daniel@gluo.nz, kent.overstreet@linux.dev,
 djwong@kernel.org
Cc: linux-xfs@vger.kernel.org, linux-bcachefs@vger.kernel.org,
 linux-kernel@vger.kernel.org
Message-ID: <170873667547.1860799.14052301166913996641.stgit@frogsfrogsfrogs>
In-Reply-To: <170873667479.1860799.16660964083961996807.stgit@frogsfrogsfrogs>
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From: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/bcachefs/super.c |    2 +
 fs/bcachefs/util.c  |  133 +++++++++++++++++++++++++++++++++++++++++++++------
 fs/bcachefs/util.h  |    4 ++
 3 files changed, 123 insertions(+), 16 deletions(-)


diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 6b23e11825e6d..b9e2c1032b920 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1262,6 +1262,8 @@ static struct bch_dev *__bch2_dev_alloc(struct bch_fs *c,
 
 	bch2_time_stats_init(&ca->io_latency[READ]);
 	bch2_time_stats_init(&ca->io_latency[WRITE]);
+	ca->io_latency[READ].quantiles_enabled = true;
+	ca->io_latency[WRITE].quantiles_enabled = true;
 
 	ca->mi = bch2_mi_to_cpu(member);
 
diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
index 902f6b1a8a142..4c63f81e18bc4 100644
--- a/fs/bcachefs/util.c
+++ b/fs/bcachefs/util.c
@@ -506,10 +506,8 @@ static inline void pr_name_and_units(struct printbuf *out, const char *name, u64
 
 void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats)
 {
-	const struct time_unit *u;
 	s64 f_mean = 0, d_mean = 0;
-	u64 q, last_q = 0, f_stddev = 0, d_stddev = 0;
-	int i;
+	u64 f_stddev = 0, d_stddev = 0;
 
 	if (stats->buffer) {
 		int cpu;
@@ -608,19 +606,122 @@ void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats
 
 	printbuf_tabstops_reset(out);
 
-	i = eytzinger0_first(NR_QUANTILES);
-	u = pick_time_units(stats->quantiles.entries[i].m);
-
-	prt_printf(out, "quantiles (%s):\t", u->name);
-	eytzinger0_for_each(i, NR_QUANTILES) {
-		bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
-
-		q = max(stats->quantiles.entries[i].m, last_q);
-		prt_printf(out, "%llu ",
-		       div_u64(q, u->nsecs));
-		if (is_last)
-			prt_newline(out);
-		last_q = q;
+	if (stats->quantiles_enabled) {
+		int i = eytzinger0_first(NR_QUANTILES);
+		const struct time_unit *u =
+			pick_time_units(stats->quantiles.entries[i].m);
+		u64 last_q = 0;
+
+		prt_printf(out, "quantiles (%s):\t", u->name);
+		eytzinger0_for_each(i, NR_QUANTILES) {
+			bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
+
+			u64 q = max(stats->quantiles.entries[i].m, last_q);
+			prt_printf(out, "%llu ", div_u64(q, u->nsecs));
+			if (is_last)
+				prt_newline(out);
+			last_q = q;
+		}
+	}
+}
+
+#include <linux/seq_buf.h>
+
+static void seq_buf_time_units_aligned(struct seq_buf *out, u64 ns)
+{
+	const struct time_unit *u = pick_time_units(ns);
+
+	seq_buf_printf(out, "%8llu %s", div64_u64(ns, u->nsecs), u->name);
+}
+
+void bch2_time_stats_to_seq_buf(struct seq_buf *out, struct bch2_time_stats *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)
+			__bch2_time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
+		spin_unlock_irq(&stats->lock);
+	}
+
+	/*
+	 * avoid divide by zero
+	 */
+	if (stats->freq_stats.n) {
+		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);
+	}
+
+	seq_buf_printf(out, "count: %llu\n", stats->duration_stats.n);
+
+	seq_buf_printf(out, "                       since mount        recent\n");
+
+	seq_buf_printf(out, "duration of events\n");
+
+	seq_buf_printf(out, "  min:                     ");
+	seq_buf_time_units_aligned(out, stats->min_duration);
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  max:                     ");
+	seq_buf_time_units_aligned(out, stats->max_duration);
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  total:                   ");
+	seq_buf_time_units_aligned(out, stats->total_duration);
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  mean:                    ");
+	seq_buf_time_units_aligned(out, d_mean);
+	seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->duration_stats_weighted));
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  stddev:                  ");
+	seq_buf_time_units_aligned(out, d_stddev);
+	seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->duration_stats_weighted));
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "time between events\n");
+
+	seq_buf_printf(out, "  min:                     ");
+	seq_buf_time_units_aligned(out, stats->min_freq);
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  max:                     ");
+	seq_buf_time_units_aligned(out, stats->max_freq);
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  mean:                    ");
+	seq_buf_time_units_aligned(out, f_mean);
+	seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->freq_stats_weighted));
+	seq_buf_printf(out, "\n");
+
+	seq_buf_printf(out, "  stddev:                  ");
+	seq_buf_time_units_aligned(out, f_stddev);
+	seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->freq_stats_weighted));
+	seq_buf_printf(out, "\n");
+
+	if (stats->quantiles_enabled) {
+		int i = eytzinger0_first(NR_QUANTILES);
+		const struct time_unit *u =
+			pick_time_units(stats->quantiles.entries[i].m);
+		u64 last_q = 0;
+
+		prt_printf(out, "quantiles (%s):\t", u->name);
+		eytzinger0_for_each(i, NR_QUANTILES) {
+			bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
+
+			u64 q = max(stats->quantiles.entries[i].m, last_q);
+			seq_buf_printf(out, "%llu ", div_u64(q, u->nsecs));
+			if (is_last)
+				seq_buf_printf(out, "\n");
+			last_q = q;
+		}
 	}
 }
 #else
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index c3b11c3d24ea9..7ff2d4fe26f68 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -382,6 +382,7 @@ struct bch2_time_stat_buffer {
 
 struct bch2_time_stats {
 	spinlock_t	lock;
+	bool		quantiles_enabled;
 	/* all fields are in nanoseconds */
 	u64             min_duration;
 	u64		max_duration;
@@ -435,6 +436,9 @@ static inline bool track_event_change(struct bch2_time_stats *stats,
 
 void bch2_time_stats_to_text(struct printbuf *, struct bch2_time_stats *);
 
+struct seq_buf;
+void bch2_time_stats_to_seq_buf(struct seq_buf *, struct bch2_time_stats *);
+
 void bch2_time_stats_exit(struct bch2_time_stats *);
 void bch2_time_stats_init(struct bch2_time_stats *);