bcachefs: pull out time_stats.[ch]

prep work for lifting out of fs/bcachefs/

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

11 files changed, 326 insertions, 279 deletions

diff --git a/fs/bcachefs/Makefile b/fs/bcachefs/Makefile
index 3433959d4f35..b02796c8a595 100644
--- a/fs/bcachefs/Makefile
+++ b/fs/bcachefs/Makefile
@@ -82,6 +82,7 @@ bcachefs-y		:=	\
 	super-io.o		\
 	sysfs.o			\
 	tests.o			\
+	time_stats.o		\
 	thread_with_file.o	\
 	trace.o			\
 	two_state_shared_lock.o	\
diff --git a/fs/bcachefs/alloc_foreground.c b/fs/bcachefs/alloc_foreground.c
index 633d3223b353..ca58193dd902 100644
--- a/fs/bcachefs/alloc_foreground.c
+++ b/fs/bcachefs/alloc_foreground.c
@@ -236,8 +236,7 @@ static struct open_bucket *__try_alloc_bucket(struct bch_fs *c, struct bch_dev *
 		if (cl)
 			closure_wait(&c->open_buckets_wait, cl);
 
-		track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket],
-				   &c->blocked_allocate_open_bucket, true);
+		track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket], true);
 		spin_unlock(&c->freelist_lock);
 		return ERR_PTR(-BCH_ERR_open_buckets_empty);
 	}
@@ -263,11 +262,8 @@ static struct open_bucket *__try_alloc_bucket(struct bch_fs *c, struct bch_dev *
 	ca->nr_open_buckets++;
 	bch2_open_bucket_hash_add(c, ob);
 
-	track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket],
-			   &c->blocked_allocate_open_bucket, false);
-
-	track_event_change(&c->times[BCH_TIME_blocked_allocate],
-			   &c->blocked_allocate, false);
+	track_event_change(&c->times[BCH_TIME_blocked_allocate_open_bucket], false);
+	track_event_change(&c->times[BCH_TIME_blocked_allocate], false);
 
 	spin_unlock(&c->freelist_lock);
 	return ob;
@@ -555,8 +551,7 @@ again:
 			goto again;
 		}
 
-		track_event_change(&c->times[BCH_TIME_blocked_allocate],
-				   &c->blocked_allocate, true);
+		track_event_change(&c->times[BCH_TIME_blocked_allocate], true);
 
 		ob = ERR_PTR(-BCH_ERR_freelist_empty);
 		goto err;
diff --git a/fs/bcachefs/bcachefs.h b/fs/bcachefs/bcachefs.h
index af7c798945f1..17a5a7151901 100644
--- a/fs/bcachefs/bcachefs.h
+++ b/fs/bcachefs/bcachefs.h
@@ -212,6 +212,7 @@
 #include "recovery_types.h"
 #include "sb-errors_types.h"
 #include "seqmutex.h"
+#include "time_stats.h"
 #include "util.h"
 
 #ifdef CONFIG_BCACHEFS_DEBUG
@@ -924,8 +925,6 @@ struct bch_fs {
 	/* ALLOCATOR */
 	spinlock_t		freelist_lock;
 	struct closure_waitlist	freelist_wait;
-	u64			blocked_allocate;
-	u64			blocked_allocate_open_bucket;
 
 	open_bucket_idx_t	open_buckets_freelist;
 	open_bucket_idx_t	open_buckets_nr_free;
diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 59d6e262277f..f314b2e78ec3 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -566,8 +566,7 @@ out:
 		ret = -BCH_ERR_journal_res_get_blocked;
 
 	if (ret == JOURNAL_ERR_max_in_flight &&
-	    track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight],
-			       &j->max_in_flight_start, true)) {
+	    track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight], true)) {
 
 		struct printbuf buf = PRINTBUF;
 		prt_printf(&buf, "seq %llu\n", journal_cur_seq(j));
diff --git a/fs/bcachefs/journal_io.c b/fs/bcachefs/journal_io.c
index 8ded059591c7..d76c3c0c203f 100644
--- a/fs/bcachefs/journal_io.c
+++ b/fs/bcachefs/journal_io.c
@@ -1680,8 +1680,7 @@ static CLOSURE_CALLBACK(journal_write_done)
 		bch2_journal_reclaim_fast(j);
 		bch2_journal_space_available(j);
 
-		track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight],
-				   &j->max_in_flight_start, false);
+		track_event_change(&c->times[BCH_TIME_blocked_journal_max_in_flight], false);
 
 		journal_wake(j);
 	}
diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c
index b975b5727471..ab811c0dad26 100644
--- a/fs/bcachefs/journal_reclaim.c
+++ b/fs/bcachefs/journal_reclaim.c
@@ -62,12 +62,9 @@ void bch2_journal_set_watermark(struct journal *j)
 		? BCH_WATERMARK_reclaim
 		: BCH_WATERMARK_stripe;
 
-	if (track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_space],
-			       &j->low_on_space_start, low_on_space) ||
-	    track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_pin],
-			       &j->low_on_pin_start, low_on_pin) ||
-	    track_event_change(&c->times[BCH_TIME_blocked_write_buffer_full],
-			       &j->write_buffer_full_start, low_on_wb))
+	if (track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_space], low_on_space) ||
+	    track_event_change(&c->times[BCH_TIME_blocked_journal_low_on_pin], low_on_pin) ||
+	    track_event_change(&c->times[BCH_TIME_blocked_write_buffer_full], low_on_wb))
 		trace_and_count(c, journal_full, c);
 
 	swap(watermark, j->watermark);
diff --git a/fs/bcachefs/journal_types.h b/fs/bcachefs/journal_types.h
index 3696aac3ccb7..8c053cb64ca5 100644
--- a/fs/bcachefs/journal_types.h
+++ b/fs/bcachefs/journal_types.h
@@ -287,11 +287,6 @@ struct journal {
 	u64			nr_noflush_writes;
 	u64			entry_bytes_written;
 
-	u64			low_on_space_start;
-	u64			low_on_pin_start;
-	u64			max_in_flight_start;
-	u64			write_buffer_full_start;
-
 	struct bch2_time_stats	*flush_write_time;
 	struct bch2_time_stats	*noflush_write_time;
 	struct bch2_time_stats	*flush_seq_time;
diff --git a/fs/bcachefs/time_stats.c b/fs/bcachefs/time_stats.c
new file mode 100644
index 000000000000..d2f7ddbf6c31
--- /dev/null
+++ b/fs/bcachefs/time_stats.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/preempt.h>
+#include <linux/time.h>
+#include <linux/spinlock.h>
+
+#include "eytzinger.h"
+#include "time_stats.h"
+
+static const struct time_unit time_units[] = {
+	{ "ns",		1		 },
+	{ "us",		NSEC_PER_USEC	 },
+	{ "ms",		NSEC_PER_MSEC	 },
+	{ "s",		NSEC_PER_SEC	 },
+	{ "m",          (u64) NSEC_PER_SEC * 60},
+	{ "h",          (u64) NSEC_PER_SEC * 3600},
+	{ "eon",        U64_MAX          },
+};
+
+const struct time_unit *bch2_pick_time_units(u64 ns)
+{
+	const struct time_unit *u;
+
+	for (u = time_units;
+	     u + 1 < time_units + ARRAY_SIZE(time_units) &&
+	     ns >= u[1].nsecs << 1;
+	     u++)
+		;
+
+	return u;
+}
+
+static void quantiles_update(struct quantiles *q, u64 v)
+{
+	unsigned i = 0;
+
+	while (i < ARRAY_SIZE(q->entries)) {
+		struct quantile_entry *e = q->entries + i;
+
+		if (unlikely(!e->step)) {
+			e->m = v;
+			e->step = max_t(unsigned, v / 2, 1024);
+		} else if (e->m > v) {
+			e->m = e->m >= e->step
+				? e->m - e->step
+				: 0;
+		} else if (e->m < v) {
+			e->m = e->m + e->step > e->m
+				? e->m + e->step
+				: U32_MAX;
+		}
+
+		if ((e->m > v ? e->m - v : v - e->m) < e->step)
+			e->step = max_t(unsigned, e->step / 2, 1);
+
+		if (v >= e->m)
+			break;
+
+		i = eytzinger0_child(i, v > e->m);
+	}
+}
+
+static inline void time_stats_update_one(struct bch2_time_stats *stats,
+					      u64 start, u64 end)
+{
+	u64 duration, freq;
+
+	if (time_after64(end, start)) {
+		duration = end - start;
+		mean_and_variance_update(&stats->duration_stats, duration);
+		mean_and_variance_weighted_update(&stats->duration_stats_weighted, duration);
+		stats->max_duration = max(stats->max_duration, duration);
+		stats->min_duration = min(stats->min_duration, duration);
+		stats->total_duration += duration;
+
+		if (stats->quantiles_enabled)
+			quantiles_update(&stats->quantiles, duration);
+	}
+
+	if (stats->last_event && time_after64(end, stats->last_event)) {
+		freq = end - stats->last_event;
+		mean_and_variance_update(&stats->freq_stats, freq);
+		mean_and_variance_weighted_update(&stats->freq_stats_weighted, freq);
+		stats->max_freq = max(stats->max_freq, freq);
+		stats->min_freq = min(stats->min_freq, freq);
+	}
+
+	stats->last_event = end;
+}
+
+void __bch2_time_stats_clear_buffer(struct bch2_time_stats *stats,
+				    struct time_stat_buffer *b)
+{
+	for (struct time_stat_buffer_entry *i = b->entries;
+	     i < b->entries + ARRAY_SIZE(b->entries);
+	     i++)
+		time_stats_update_one(stats, i->start, i->end);
+	b->nr = 0;
+}
+
+static noinline void time_stats_clear_buffer(struct bch2_time_stats *stats,
+					     struct time_stat_buffer *b)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&stats->lock, flags);
+	__bch2_time_stats_clear_buffer(stats, b);
+	spin_unlock_irqrestore(&stats->lock, flags);
+}
+
+void __bch2_time_stats_update(struct bch2_time_stats *stats, u64 start, u64 end)
+{
+	unsigned long flags;
+
+	WARN_ONCE(!stats->duration_stats_weighted.weight ||
+		  !stats->freq_stats_weighted.weight,
+		  "uninitialized bch2_time_stats");
+
+	if (!stats->buffer) {
+		spin_lock_irqsave(&stats->lock, flags);
+		time_stats_update_one(stats, start, end);
+
+		if (mean_and_variance_weighted_get_mean(stats->freq_stats_weighted) < 32 &&
+		    stats->duration_stats.n > 1024)
+			stats->buffer =
+				alloc_percpu_gfp(struct time_stat_buffer,
+						 GFP_ATOMIC);
+		spin_unlock_irqrestore(&stats->lock, flags);
+	} else {
+		struct time_stat_buffer *b;
+
+		preempt_disable();
+		b = this_cpu_ptr(stats->buffer);
+
+		BUG_ON(b->nr >= ARRAY_SIZE(b->entries));
+		b->entries[b->nr++] = (struct time_stat_buffer_entry) {
+			.start = start,
+			.end = end
+		};
+
+		if (unlikely(b->nr == ARRAY_SIZE(b->entries)))
+			time_stats_clear_buffer(stats, b);
+		preempt_enable();
+	}
+}
+
+void bch2_time_stats_exit(struct bch2_time_stats *stats)
+{
+	free_percpu(stats->buffer);
+}
+
+void bch2_time_stats_init(struct bch2_time_stats *stats)
+{
+	memset(stats, 0, sizeof(*stats));
+	stats->duration_stats_weighted.weight = 8;
+	stats->freq_stats_weighted.weight = 8;
+	stats->min_duration = U64_MAX;
+	stats->min_freq = U64_MAX;
+	spin_lock_init(&stats->lock);
+}
diff --git a/fs/bcachefs/time_stats.h b/fs/bcachefs/time_stats.h
new file mode 100644
index 000000000000..d0291ea863ba
--- /dev/null
+++ b/fs/bcachefs/time_stats.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * bch2_time_stats - collect statistics on events that have a duration, with nicely
+ * formatted textual output on demand
+ *
+ * - percpu buffering of event collection: cheap enough to shotgun
+ *   everywhere without worrying about overhead
+ *
+ * tracks:
+ *  - number of events
+ *  - maximum event duration ever seen
+ *  - sum of all event durations
+ *  - average event duration, standard and weighted
+ *  - standard deviation of event durations, standard and weighted
+ * and analagous statistics for the frequency of events
+ *
+ * We provide both mean and weighted mean (exponentially weighted), and standard
+ * deviation and weighted standard deviation, to give an efficient-to-compute
+ * view of current behaviour versus. average behaviour - "did this event source
+ * just become wonky, or is this typical?".
+ *
+ * Particularly useful for tracking down latency issues.
+ */
+#ifndef _BCACHEFS_TIME_STATS_H
+#define _BCACHEFS_TIME_STATS_H
+
+#include <linux/sched/clock.h>
+#include <linux/spinlock_types.h>
+
+#include "mean_and_variance.h"
+
+struct time_unit {
+	const char	*name;
+	u64		nsecs;
+};
+
+/*
+ * given a nanosecond value, pick the preferred time units for printing:
+ */
+const struct time_unit *bch2_pick_time_units(u64 ns);
+
+/*
+ * quantiles - do not use:
+ *
+ * Only enabled if bch2_time_stats->quantiles_enabled has been manually set - don't
+ * use in new code.
+ */
+
+#define NR_QUANTILES	15
+#define QUANTILE_IDX(i)	inorder_to_eytzinger0(i, NR_QUANTILES)
+#define QUANTILE_FIRST	eytzinger0_first(NR_QUANTILES)
+#define QUANTILE_LAST	eytzinger0_last(NR_QUANTILES)
+
+struct quantiles {
+	struct quantile_entry {
+		u64	m;
+		u64	step;
+	}		entries[NR_QUANTILES];
+};
+
+struct time_stat_buffer {
+	unsigned	nr;
+	struct time_stat_buffer_entry {
+		u64	start;
+		u64	end;
+	}		entries[32];
+};
+
+struct bch2_time_stats {
+	spinlock_t	lock;
+	bool		quantiles_enabled;
+	/* all fields are in nanoseconds */
+	u64             min_duration;
+	u64		max_duration;
+	u64		total_duration;
+	u64             max_freq;
+	u64             min_freq;
+	u64		last_event;
+	u64		last_event_start;
+	struct quantiles quantiles;
+
+	struct mean_and_variance	  duration_stats;
+	struct mean_and_variance_weighted duration_stats_weighted;
+	struct mean_and_variance	  freq_stats;
+	struct mean_and_variance_weighted freq_stats_weighted;
+	struct time_stat_buffer __percpu *buffer;
+};
+
+void __bch2_time_stats_clear_buffer(struct bch2_time_stats *, struct time_stat_buffer *);
+void __bch2_time_stats_update(struct bch2_time_stats *stats, u64, u64);
+
+/**
+ * time_stats_update - collect a new event being tracked
+ *
+ * @stats	- bch2_time_stats to update
+ * @start	- start time of event, recorded with local_clock()
+ *
+ * The end duration of the event will be the current time
+ */
+static inline void bch2_time_stats_update(struct bch2_time_stats *stats, u64 start)
+{
+	__bch2_time_stats_update(stats, start, local_clock());
+}
+
+/**
+ * track_event_change - track state change events
+ *
+ * @stats	- bch2_time_stats to update
+ * @v		- new state, true or false
+ *
+ * Use this when tracking time stats for state changes, i.e. resource X becoming
+ * blocked/unblocked.
+ */
+static inline bool track_event_change(struct bch2_time_stats *stats, bool v)
+{
+	if (v != !!stats->last_event_start) {
+		if (!v) {
+			bch2_time_stats_update(stats, stats->last_event_start);
+			stats->last_event_start = 0;
+		} else {
+			stats->last_event_start = local_clock() ?: 1;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+void bch2_time_stats_exit(struct bch2_time_stats *);
+void bch2_time_stats_init(struct bch2_time_stats *);
+
+#endif /* _BCACHEFS_TIME_STATS_H */
diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
index bd3687a726f7..96de039fc890 100644
--- a/fs/bcachefs/util.c
+++ b/fs/bcachefs/util.c
@@ -337,157 +337,16 @@ void bch2_prt_datetime(struct printbuf *out, time64_t sec)
 }
 #endif
 
-static const struct time_unit {
-	const char	*name;
-	u64		nsecs;
-} time_units[] = {
-	{ "ns",		1		 },
-	{ "us",		NSEC_PER_USEC	 },
-	{ "ms",		NSEC_PER_MSEC	 },
-	{ "s",		NSEC_PER_SEC	 },
-	{ "m",          (u64) NSEC_PER_SEC * 60},
-	{ "h",          (u64) NSEC_PER_SEC * 3600},
-	{ "eon",        U64_MAX          },
-};
-
-static const struct time_unit *pick_time_units(u64 ns)
-{
-	const struct time_unit *u;
-
-	for (u = time_units;
-	     u + 1 < time_units + ARRAY_SIZE(time_units) &&
-	     ns >= u[1].nsecs << 1;
-	     u++)
-		;
-
-	return u;
-}
-
 void bch2_pr_time_units(struct printbuf *out, u64 ns)
 {
-	const struct time_unit *u = pick_time_units(ns);
+	const struct time_unit *u = bch2_pick_time_units(ns);
 
 	prt_printf(out, "%llu %s", div_u64(ns, u->nsecs), u->name);
 }
 
-/* time stats: */
-
-#ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
-static void bch2_quantiles_update(struct bch2_quantiles *q, u64 v)
-{
-	unsigned i = 0;
-
-	while (i < ARRAY_SIZE(q->entries)) {
-		struct bch2_quantile_entry *e = q->entries + i;
-
-		if (unlikely(!e->step)) {
-			e->m = v;
-			e->step = max_t(unsigned, v / 2, 1024);
-		} else if (e->m > v) {
-			e->m = e->m >= e->step
-				? e->m - e->step
-				: 0;
-		} else if (e->m < v) {
-			e->m = e->m + e->step > e->m
-				? e->m + e->step
-				: U32_MAX;
-		}
-
-		if ((e->m > v ? e->m - v : v - e->m) < e->step)
-			e->step = max_t(unsigned, e->step / 2, 1);
-
-		if (v >= e->m)
-			break;
-
-		i = eytzinger0_child(i, v > e->m);
-	}
-}
-
-static inline void bch2_time_stats_update_one(struct bch2_time_stats *stats,
-					      u64 start, u64 end)
-{
-	u64 duration, freq;
-
-	if (time_after64(end, start)) {
-		duration = end - start;
-		mean_and_variance_update(&stats->duration_stats, duration);
-		mean_and_variance_weighted_update(&stats->duration_stats_weighted, duration);
-		stats->max_duration = max(stats->max_duration, duration);
-		stats->min_duration = min(stats->min_duration, duration);
-		stats->total_duration += duration;
-		bch2_quantiles_update(&stats->quantiles, duration);
-	}
-
-	if (stats->last_event && time_after64(end, stats->last_event)) {
-		freq = end - stats->last_event;
-		mean_and_variance_update(&stats->freq_stats, freq);
-		mean_and_variance_weighted_update(&stats->freq_stats_weighted, freq);
-		stats->max_freq = max(stats->max_freq, freq);
-		stats->min_freq = min(stats->min_freq, freq);
-	}
-
-	stats->last_event = end;
-}
-
-static void __bch2_time_stats_clear_buffer(struct bch2_time_stats *stats,
-					   struct bch2_time_stat_buffer *b)
-{
-	for (struct bch2_time_stat_buffer_entry *i = b->entries;
-	     i < b->entries + ARRAY_SIZE(b->entries);
-	     i++)
-		bch2_time_stats_update_one(stats, i->start, i->end);
-	b->nr = 0;
-}
-
-static noinline void bch2_time_stats_clear_buffer(struct bch2_time_stats *stats,
-						  struct bch2_time_stat_buffer *b)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&stats->lock, flags);
-	__bch2_time_stats_clear_buffer(stats, b);
-	spin_unlock_irqrestore(&stats->lock, flags);
-}
-
-void __bch2_time_stats_update(struct bch2_time_stats *stats, u64 start, u64 end)
-{
-	unsigned long flags;
-
-	WARN_ONCE(!stats->duration_stats_weighted.weight ||
-		  !stats->freq_stats_weighted.weight,
-		  "uninitialized time_stats");
-
-	if (!stats->buffer) {
-		spin_lock_irqsave(&stats->lock, flags);
-		bch2_time_stats_update_one(stats, start, end);
-
-		if (mean_and_variance_weighted_get_mean(stats->freq_stats_weighted) < 32 &&
-		    stats->duration_stats.n > 1024)
-			stats->buffer =
-				alloc_percpu_gfp(struct bch2_time_stat_buffer,
-						 GFP_ATOMIC);
-		spin_unlock_irqrestore(&stats->lock, flags);
-	} else {
-		struct bch2_time_stat_buffer *b;
-
-		preempt_disable();
-		b = this_cpu_ptr(stats->buffer);
-
-		BUG_ON(b->nr >= ARRAY_SIZE(b->entries));
-		b->entries[b->nr++] = (struct bch2_time_stat_buffer_entry) {
-			.start = start,
-			.end = end
-		};
-
-		if (unlikely(b->nr == ARRAY_SIZE(b->entries)))
-			bch2_time_stats_clear_buffer(stats, b);
-		preempt_enable();
-	}
-}
-
 static void bch2_pr_time_units_aligned(struct printbuf *out, u64 ns)
 {
-	const struct time_unit *u = pick_time_units(ns);
+	const struct time_unit *u = bch2_pick_time_units(ns);
 
 	prt_printf(out, "%llu ", div64_u64(ns, u->nsecs));
 	prt_tab_rjust(out);
@@ -506,10 +365,8 @@ 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;
@@ -608,39 +465,24 @@ 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 =
+			bch2_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;
+		}
 	}
 }
-#else
-void bch2_time_stats_to_text(struct printbuf *out, struct bch2_time_stats *stats) {}
-#endif
-
-void bch2_time_stats_exit(struct bch2_time_stats *stats)
-{
-	free_percpu(stats->buffer);
-}
-
-void bch2_time_stats_init(struct bch2_time_stats *stats)
-{
-	memset(stats, 0, sizeof(*stats));
-	stats->duration_stats_weighted.weight = 8;
-	stats->freq_stats_weighted.weight = 8;
-	stats->min_duration = U64_MAX;
-	stats->min_freq = U64_MAX;
-	spin_lock_init(&stats->lock);
-}
 
 /* ratelimit: */
 
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index 4aba415ab5b8..7ffbddb80400 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -21,6 +21,7 @@
 #include "mean_and_variance.h"
 
 #include "darray.h"
+#include "time_stats.h"
 
 struct closure;
 
@@ -329,84 +330,8 @@ static inline void prt_bdevname(struct printbuf *out, struct block_device *bdev)
 #endif
 }
 
-#define NR_QUANTILES	15
-#define QUANTILE_IDX(i)	inorder_to_eytzinger0(i, NR_QUANTILES)
-#define QUANTILE_FIRST	eytzinger0_first(NR_QUANTILES)
-#define QUANTILE_LAST	eytzinger0_last(NR_QUANTILES)
-
-struct bch2_quantiles {
-	struct bch2_quantile_entry {
-		u64	m;
-		u64	step;
-	}		entries[NR_QUANTILES];
-};
-
-struct bch2_time_stat_buffer {
-	unsigned	nr;
-	struct bch2_time_stat_buffer_entry {
-		u64	start;
-		u64	end;
-	}		entries[32];
-};
-
-struct bch2_time_stats {
-	spinlock_t	lock;
-	/* all fields are in nanoseconds */
-	u64             min_duration;
-	u64		max_duration;
-	u64		total_duration;
-	u64             max_freq;
-	u64             min_freq;
-	u64		last_event;
-	struct bch2_quantiles quantiles;
-
-	struct mean_and_variance	  duration_stats;
-	struct mean_and_variance_weighted duration_stats_weighted;
-	struct mean_and_variance	  freq_stats;
-	struct mean_and_variance_weighted freq_stats_weighted;
-	struct bch2_time_stat_buffer __percpu *buffer;
-};
-
-#ifndef CONFIG_BCACHEFS_NO_LATENCY_ACCT
-void __bch2_time_stats_update(struct bch2_time_stats *stats, u64, u64);
-
-static inline void bch2_time_stats_update(struct bch2_time_stats *stats, u64 start)
-{
-	__bch2_time_stats_update(stats, start, local_clock());
-}
-
-static inline bool track_event_change(struct bch2_time_stats *stats,
-				      u64 *start, bool v)
-{
-	if (v != !!*start) {
-		if (!v) {
-			bch2_time_stats_update(stats, *start);
-			*start = 0;
-		} else {
-			*start = local_clock() ?: 1;
-			return true;
-		}
-	}
-
-	return false;
-}
-#else
-static inline void __bch2_time_stats_update(struct bch2_time_stats *stats, u64 start, u64 end) {}
-static inline void bch2_time_stats_update(struct bch2_time_stats *stats, u64 start) {}
-static inline bool track_event_change(struct bch2_time_stats *stats,
-				      u64 *start, bool v)
-{
-	bool ret = v && !*start;
-	*start = v;
-	return ret;
-}
-#endif
-
 void bch2_time_stats_to_text(struct printbuf *, struct bch2_time_stats *);
 
-void bch2_time_stats_exit(struct bch2_time_stats *);
-void bch2_time_stats_init(struct bch2_time_stats *);
-
 #define ewma_add(ewma, val, weight)					\
 ({									\
 	typeof(ewma) _ewma = (ewma);					\