[PATCH 5/5] bcache: Convert to lib/time_stats

[Kent Overstreet <kent.overstreet@linux.dev>]

delete bcache's time stats code, convert to newer version from bcachefs.

example output:

root@moria-kvm:/sys/fs/bcache/bdaedb8c-4554-4dd2-87e4-276e51eb47cc# cat internal/btree_sort_times
count: 6414
                       since mount        recent
duration of events
  min:                          440 ns
  max:                         1102 us
  total:                        674 ms
  mean:                         105 us     102 us
  stddev:                       101 us      88 us
time between events
  min:                          881 ns
  max:                            3 s
  mean:                           7 ms       6 ms
  stddev:                        52 ms       6 ms

Cc: Coly Li <colyli@suse.de>
Cc: linux-bcache@vger.kernel.org
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
 drivers/md/bcache/Kconfig  |  1 +
 drivers/md/bcache/bcache.h |  1 +
 drivers/md/bcache/bset.c   |  6 +++--
 drivers/md/bcache/bset.h   |  1 +
 drivers/md/bcache/btree.c  |  6 ++---
 drivers/md/bcache/super.c  |  7 +++++
 drivers/md/bcache/sysfs.c  | 25 +++++++++---------
 drivers/md/bcache/util.c   | 30 ----------------------
 drivers/md/bcache/util.h   | 52 +++++---------------------------------
 9 files changed, 37 insertions(+), 92 deletions(-)

diff --git a/drivers/md/bcache/Kconfig b/drivers/md/bcache/Kconfig
index b2d10063d35f..7ea057983d3d 100644
--- a/drivers/md/bcache/Kconfig
+++ b/drivers/md/bcache/Kconfig
@@ -5,6 +5,7 @@ config BCACHE
 	select BLOCK_HOLDER_DEPRECATED if SYSFS
 	select CRC64
 	select CLOSURES
+	select TIME_STATS
 	help
 	Allows a block device to be used as cache for other devices; uses
 	a btree for indexing and the layout is optimized for SSDs.
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 6ae2329052c9..76e7b494c394 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -186,6 +186,7 @@
 #include <linux/rbtree.h>
 #include <linux/rwsem.h>
 #include <linux/refcount.h>
+#include <linux/time_stats.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
 #include <linux/kthread.h>
diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index 2bba4d6aaaa2..31c08d4ab83b 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -1177,6 +1177,7 @@ struct bkey *bch_btree_iter_next_filter(struct btree_iter *iter,
 
 void bch_bset_sort_state_free(struct bset_sort_state *state)
 {
+	time_stats_exit(&state->time);
 	mempool_exit(&state->pool);
 }
 
@@ -1184,6 +1185,7 @@ int bch_bset_sort_state_init(struct bset_sort_state *state,
 			     unsigned int page_order)
 {
 	spin_lock_init(&state->time.lock);
+	time_stats_init(&state->time);
 
 	state->page_order = page_order;
 	state->crit_factor = int_sqrt(1 << page_order);
@@ -1286,7 +1288,7 @@ static void __btree_sort(struct btree_keys *b, struct btree_iter *iter,
 	bch_bset_build_written_tree(b);
 
 	if (!start)
-		bch_time_stats_update(&state->time, start_time);
+		time_stats_update(&state->time, start_time);
 }
 
 void bch_btree_sort_partial(struct btree_keys *b, unsigned int start,
@@ -1329,7 +1331,7 @@ void bch_btree_sort_into(struct btree_keys *b, struct btree_keys *new,
 
 	btree_mergesort(b, new->set->data, &iter, false, true);
 
-	bch_time_stats_update(&state->time, start_time);
+	time_stats_update(&state->time, start_time);
 
 	new->set->size = 0; // XXX: why?
 }
diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h
index d795c84246b0..13e524ad7783 100644
--- a/drivers/md/bcache/bset.h
+++ b/drivers/md/bcache/bset.h
@@ -3,6 +3,7 @@
 #define _BCACHE_BSET_H
 
 #include <linux/kernel.h>
+#include <linux/time_stats.h>
 #include <linux/types.h>
 
 #include "bcache_ondisk.h"
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 196cdacce38f..0ed337c5f0dc 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -270,7 +270,7 @@ static void bch_btree_node_read(struct btree *b)
 		goto err;
 
 	bch_btree_node_read_done(b);
-	bch_time_stats_update(&b->c->btree_read_time, start_time);
+	time_stats_update(&b->c->btree_read_time, start_time);
 
 	return;
 err:
@@ -1852,7 +1852,7 @@ static void bch_btree_gc(struct cache_set *c)
 	bch_btree_gc_finish(c);
 	wake_up_allocators(c);
 
-	bch_time_stats_update(&c->btree_gc_time, start_time);
+	time_stats_update(&c->btree_gc_time, start_time);
 
 	stats.key_bytes *= sizeof(uint64_t);
 	stats.data	<<= 9;
@@ -2343,7 +2343,7 @@ static int btree_split(struct btree *b, struct btree_op *op,
 	btree_node_free(b);
 	rw_unlock(true, n1);
 
-	bch_time_stats_update(&b->c->btree_split_time, start_time);
+	time_stats_update(&b->c->btree_split_time, start_time);
 
 	return 0;
 err_free2:
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index dc3f50f69714..625e4883299c 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1676,6 +1676,9 @@ static CLOSURE_CALLBACK(cache_set_free)
 
 	debugfs_remove(c->debug);
 
+	time_stats_exit(&c->btree_read_time);
+	time_stats_exit(&c->btree_split_time);
+	time_stats_exit(&c->btree_gc_time);
 	bch_open_buckets_free(c);
 	bch_btree_cache_free(c);
 	bch_journal_free(c);
@@ -1913,6 +1916,10 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 	INIT_LIST_HEAD(&c->btree_cache_freed);
 	INIT_LIST_HEAD(&c->data_buckets);
 
+	time_stats_init(&c->btree_gc_time);
+	time_stats_init(&c->btree_split_time);
+	time_stats_init(&c->btree_read_time);
+
 	iter_size = ((meta_bucket_pages(sb) * PAGE_SECTORS) / sb->block_size + 1) *
 		sizeof(struct btree_iter_set);
 
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index a438efb66069..01cc5c632f08 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -14,6 +14,7 @@
 #include "features.h"
 
 #include <linux/blkdev.h>
+#include <linux/seq_buf.h>
 #include <linux/sort.h>
 #include <linux/sched/clock.h>
 
@@ -79,10 +80,10 @@ read_attribute(active_journal_entries);
 read_attribute(backing_dev_name);
 read_attribute(backing_dev_uuid);
 
-sysfs_time_stats_attribute(btree_gc,	sec, ms);
-sysfs_time_stats_attribute(btree_split, sec, us);
-sysfs_time_stats_attribute(btree_sort,	ms,  us);
-sysfs_time_stats_attribute(btree_read,	ms,  us);
+read_attribute(btree_gc_times);
+read_attribute(btree_split_times);
+read_attribute(btree_sort_times);
+read_attribute(btree_read_times);
 
 read_attribute(btree_nodes);
 read_attribute(btree_used_percent);
@@ -743,10 +744,10 @@ SHOW(__bch_cache_set)
 	sysfs_print(btree_cache_max_chain,	bch_cache_max_chain(c));
 	sysfs_print(cache_available_percent,	100 - c->gc_stats.in_use);
 
-	sysfs_print_time_stats(&c->btree_gc_time,	btree_gc, sec, ms);
-	sysfs_print_time_stats(&c->btree_split_time,	btree_split, sec, us);
-	sysfs_print_time_stats(&c->sort.time,		btree_sort, ms, us);
-	sysfs_print_time_stats(&c->btree_read_time,	btree_read, ms, us);
+	sysfs_print_time_stats(&c->btree_gc_time,	btree_gc_times);
+	sysfs_print_time_stats(&c->btree_split_time,	btree_split_times);
+	sysfs_print_time_stats(&c->sort.time,		btree_sort_times);
+	sysfs_print_time_stats(&c->btree_read_time,	btree_read_times);
 
 	sysfs_print(btree_used_percent,	bch_btree_used(c));
 	sysfs_print(btree_nodes,	c->gc_stats.nodes);
@@ -989,10 +990,10 @@ KTYPE(bch_cache_set);
 static struct attribute *bch_cache_set_internal_attrs[] = {
 	&sysfs_active_journal_entries,
 
-	sysfs_time_stats_attribute_list(btree_gc, sec, ms)
-	sysfs_time_stats_attribute_list(btree_split, sec, us)
-	sysfs_time_stats_attribute_list(btree_sort, ms, us)
-	sysfs_time_stats_attribute_list(btree_read, ms, us)
+	&sysfs_btree_gc_times,
+	&sysfs_btree_split_times,
+	&sysfs_btree_sort_times,
+	&sysfs_btree_read_times,
 
 	&sysfs_btree_nodes,
 	&sysfs_btree_used_percent,
diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index ae380bc3992e..95282bf0f9a7 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -160,36 +160,6 @@ int bch_parse_uuid(const char *s, char *uuid)
 	return i;
 }
 
-void bch_time_stats_update(struct time_stats *stats, uint64_t start_time)
-{
-	uint64_t now, duration, last;
-
-	spin_lock(&stats->lock);
-
-	now		= local_clock();
-	duration	= time_after64(now, start_time)
-		? now - start_time : 0;
-	last		= time_after64(now, stats->last)
-		? now - stats->last : 0;
-
-	stats->max_duration = max(stats->max_duration, duration);
-
-	if (stats->last) {
-		ewma_add(stats->average_duration, duration, 8, 8);
-
-		if (stats->average_frequency)
-			ewma_add(stats->average_frequency, last, 8, 8);
-		else
-			stats->average_frequency  = last << 8;
-	} else {
-		stats->average_duration  = duration << 8;
-	}
-
-	stats->last = now ?: 1;
-
-	spin_unlock(&stats->lock);
-}
-
 /**
  * bch_next_delay() - update ratelimiting statistics and calculate next delay
  * @d: the struct bch_ratelimit to update
diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h
index f61ab1bada6c..6fcb9db4f50d 100644
--- a/drivers/md/bcache/util.h
+++ b/drivers/md/bcache/util.h
@@ -344,20 +344,6 @@ ssize_t bch_hprint(char *buf, int64_t v);
 bool bch_is_zero(const char *p, size_t n);
 int bch_parse_uuid(const char *s, char *uuid);
 
-struct time_stats {
-	spinlock_t	lock;
-	/*
-	 * all fields are in nanoseconds, averages are ewmas stored left shifted
-	 * by 8
-	 */
-	uint64_t	max_duration;
-	uint64_t	average_duration;
-	uint64_t	average_frequency;
-	uint64_t	last;
-};
-
-void bch_time_stats_update(struct time_stats *stats, uint64_t time);
-
 static inline unsigned int local_clock_us(void)
 {
 	return local_clock() >> 10;
@@ -372,40 +358,16 @@ static inline unsigned int local_clock_us(void)
 	sysfs_print(name ## _ ## stat ## _ ## units,			\
 		    div_u64((stats)->stat >> 8, NSEC_PER_ ## units))
 
-#define sysfs_print_time_stats(stats, name,				\
-			       frequency_units,				\
-			       duration_units)				\
+#define sysfs_print_time_stats(stats, name)				\
 do {									\
-	__print_time_stat(stats, name,					\
-			  average_frequency,	frequency_units);	\
-	__print_time_stat(stats, name,					\
-			  average_duration,	duration_units);	\
-	sysfs_print(name ## _ ##max_duration ## _ ## duration_units,	\
-			div_u64((stats)->max_duration,			\
-				NSEC_PER_ ## duration_units));		\
-									\
-	sysfs_print(name ## _last_ ## frequency_units, (stats)->last	\
-		    ? div_s64(local_clock() - (stats)->last,		\
-			      NSEC_PER_ ## frequency_units)		\
-		    : -1LL);						\
+	if (attr == &sysfs_##name) {					\
+		struct seq_buf seq;					\
+		seq_buf_init(&seq, buf, PAGE_SIZE);			\
+		time_stats_to_seq_buf(&seq, stats);			\
+		return seq.len;						\
+	}								\
 } while (0)
 
-#define sysfs_time_stats_attribute(name,				\
-				   frequency_units,			\
-				   duration_units)			\
-read_attribute(name ## _average_frequency_ ## frequency_units);		\
-read_attribute(name ## _average_duration_ ## duration_units);		\
-read_attribute(name ## _max_duration_ ## duration_units);		\
-read_attribute(name ## _last_ ## frequency_units)
-
-#define sysfs_time_stats_attribute_list(name,				\
-					frequency_units,		\
-					duration_units)			\
-&sysfs_ ## name ## _average_frequency_ ## frequency_units,		\
-&sysfs_ ## name ## _average_duration_ ## duration_units,		\
-&sysfs_ ## name ## _max_duration_ ## duration_units,			\
-&sysfs_ ## name ## _last_ ## frequency_units,
-
 #define ewma_add(ewma, val, weight, factor)				\
 ({									\
 	(ewma) *= (weight) - 1;						\
-- 
2.43.0