[linux-block.git] / drivers / md / bcache / stats.c

// SPDX-License-Identifier: GPL-2.0
/*
 * bcache stats code
 *
 * Copyright 2012 Google, Inc.
 */

#include "bcache.h"
#include "stats.h"
#include "btree.h"
#include "sysfs.h"

/*
 * We keep absolute totals of various statistics, and addionally a set of three
 * rolling averages.
 *
 * Every so often, a timer goes off and rescales the rolling averages.
 * accounting_rescale[] is how many times the timer has to go off before we
 * rescale each set of numbers; that gets us half lives of 5 minutes, one hour,
 * and one day.
 *
 * accounting_delay is how often the timer goes off - 22 times in 5 minutes,
 * and accounting_weight is what we use to rescale:
 *
 * pow(31 / 32, 22) ~= 1/2
 *
 * So that we don't have to increment each set of numbers every time we (say)
 * get a cache hit, we increment a single atomic_t in acc->collector, and when
 * the rescale function runs it resets the atomic counter to 0 and adds its
 * old value to each of the exported numbers.
 *
 * To reduce rounding error, the numbers in struct cache_stats are all
 * stored left shifted by 16, and scaled back in the sysfs show() function.
 */

static const unsigned DAY_RESCALE		= 288;
static const unsigned HOUR_RESCALE		= 12;
static const unsigned FIVE_MINUTE_RESCALE	= 1;
static const unsigned accounting_delay		= (HZ * 300) / 22;
static const unsigned accounting_weight		= 32;

/* sysfs reading/writing */

read_attribute(cache_hits);
read_attribute(cache_misses);
read_attribute(cache_bypass_hits);
read_attribute(cache_bypass_misses);
read_attribute(cache_hit_ratio);
read_attribute(cache_readaheads);
read_attribute(cache_miss_collisions);
read_attribute(bypassed);

SHOW(bch_stats)
{
	struct cache_stats *s =
		container_of(kobj, struct cache_stats, kobj);
#define var(stat)		(s->stat >> 16)
	var_print(cache_hits);
	var_print(cache_misses);
	var_print(cache_bypass_hits);
	var_print(cache_bypass_misses);

	sysfs_print(cache_hit_ratio,
		    DIV_SAFE(var(cache_hits) * 100,
			     var(cache_hits) + var(cache_misses)));

	var_print(cache_readaheads);
	var_print(cache_miss_collisions);
	sysfs_hprint(bypassed,	var(sectors_bypassed) << 9);
#undef var
	return 0;
}

STORE(bch_stats)
{
	return size;
}

static void bch_stats_release(struct kobject *k)
{
}

static struct attribute *bch_stats_files[] = {
	&sysfs_cache_hits,
	&sysfs_cache_misses,
	&sysfs_cache_bypass_hits,
	&sysfs_cache_bypass_misses,
	&sysfs_cache_hit_ratio,
	&sysfs_cache_readaheads,
	&sysfs_cache_miss_collisions,
	&sysfs_bypassed,
	NULL
};
static KTYPE(bch_stats);

int bch_cache_accounting_add_kobjs(struct cache_accounting *acc,
				   struct kobject *parent)
{
	int ret = kobject_add(&acc->total.kobj, parent,
			      "stats_total");
	ret = ret ?: kobject_add(&acc->five_minute.kobj, parent,
				 "stats_five_minute");
	ret = ret ?: kobject_add(&acc->hour.kobj, parent,
				 "stats_hour");
	ret = ret ?: kobject_add(&acc->day.kobj, parent,
				 "stats_day");
	return ret;
}

void bch_cache_accounting_clear(struct cache_accounting *acc)
{
	memset(&acc->total.cache_hits,
	       0,
	       sizeof(unsigned long) * 7);
}

void bch_cache_accounting_destroy(struct cache_accounting *acc)
{
	kobject_put(&acc->total.kobj);
	kobject_put(&acc->five_minute.kobj);
	kobject_put(&acc->hour.kobj);
	kobject_put(&acc->day.kobj);

	atomic_set(&acc->closing, 1);
	if (del_timer_sync(&acc->timer))
		closure_return(&acc->cl);
}

/* EWMA scaling */

static void scale_stat(unsigned long *stat)
{
	*stat =  ewma_add(*stat, 0, accounting_weight, 0);
}

static void scale_stats(struct cache_stats *stats, unsigned long rescale_at)
{
	if (++stats->rescale == rescale_at) {
		stats->rescale = 0;
		scale_stat(&stats->cache_hits);
		scale_stat(&stats->cache_misses);
		scale_stat(&stats->cache_bypass_hits);
		scale_stat(&stats->cache_bypass_misses);
		scale_stat(&stats->cache_readaheads);
		scale_stat(&stats->cache_miss_collisions);
		scale_stat(&stats->sectors_bypassed);
	}
}

static void scale_accounting(unsigned long data)
{
	struct cache_accounting *acc = (struct cache_accounting *) data;

#define move_stat(name) do {						\
	unsigned t = atomic_xchg(&acc->collector.name, 0);		\
	t <<= 16;							\
	acc->five_minute.name += t;					\
	acc->hour.name += t;						\
	acc->day.name += t;						\
	acc->total.name += t;						\
} while (0)

	move_stat(cache_hits);
	move_stat(cache_misses);
	move_stat(cache_bypass_hits);
	move_stat(cache_bypass_misses);
	move_stat(cache_readaheads);
	move_stat(cache_miss_collisions);
	move_stat(sectors_bypassed);

	scale_stats(&acc->total, 0);
	scale_stats(&acc->day, DAY_RESCALE);
	scale_stats(&acc->hour, HOUR_RESCALE);
	scale_stats(&acc->five_minute, FIVE_MINUTE_RESCALE);

	acc->timer.expires += accounting_delay;

	if (!atomic_read(&acc->closing))
		add_timer(&acc->timer);
	else
		closure_return(&acc->cl);
}

static void mark_cache_stats(struct cache_stat_collector *stats,
			     bool hit, bool bypass)
{
	if (!bypass)
		if (hit)
			atomic_inc(&stats->cache_hits);
		else
			atomic_inc(&stats->cache_misses);
	else
		if (hit)
			atomic_inc(&stats->cache_bypass_hits);
		else
			atomic_inc(&stats->cache_bypass_misses);
}

void bch_mark_cache_accounting(struct cache_set *c, struct bcache_device *d,
			       bool hit, bool bypass)
{
	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
	mark_cache_stats(&dc->accounting.collector, hit, bypass);
	mark_cache_stats(&c->accounting.collector, hit, bypass);
}

void bch_mark_cache_readahead(struct cache_set *c, struct bcache_device *d)
{
	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
	atomic_inc(&dc->accounting.collector.cache_readaheads);
	atomic_inc(&c->accounting.collector.cache_readaheads);
}

void bch_mark_cache_miss_collision(struct cache_set *c, struct bcache_device *d)
{
	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
	atomic_inc(&dc->accounting.collector.cache_miss_collisions);
	atomic_inc(&c->accounting.collector.cache_miss_collisions);
}

void bch_mark_sectors_bypassed(struct cache_set *c, struct cached_dev *dc,
			       int sectors)
{
	atomic_add(sectors, &dc->accounting.collector.sectors_bypassed);
	atomic_add(sectors, &c->accounting.collector.sectors_bypassed);
}

void bch_cache_accounting_init(struct cache_accounting *acc,
			       struct closure *parent)
{
	kobject_init(&acc->total.kobj,		&bch_stats_ktype);
	kobject_init(&acc->five_minute.kobj,	&bch_stats_ktype);
	kobject_init(&acc->hour.kobj,		&bch_stats_ktype);
	kobject_init(&acc->day.kobj,		&bch_stats_ktype);

	closure_init(&acc->cl, parent);
	init_timer(&acc->timer);
	acc->timer.expires	= jiffies + accounting_delay;
	acc->timer.data		= (unsigned long) acc;
	acc->timer.function	= scale_accounting;
	add_timer(&acc->timer);
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
cafe5635 KO	2	/*
	3	* bcache stats code
	4	*
	5	* Copyright 2012 Google, Inc.
	6	*/
	7
	8	#include "bcache.h"
	9	#include "stats.h"
	10	#include "btree.h"
cafe5635 KO	11	#include "sysfs.h"
	12
	13	/*
	14	* We keep absolute totals of various statistics, and addionally a set of three
	15	* rolling averages.
	16	*
	17	* Every so often, a timer goes off and rescales the rolling averages.
	18	* accounting_rescale[] is how many times the timer has to go off before we
	19	* rescale each set of numbers; that gets us half lives of 5 minutes, one hour,
	20	* and one day.
	21	*
	22	* accounting_delay is how often the timer goes off - 22 times in 5 minutes,
	23	* and accounting_weight is what we use to rescale:
	24	*
	25	* pow(31 / 32, 22) ~= 1/2
	26	*
	27	* So that we don't have to increment each set of numbers every time we (say)
	28	* get a cache hit, we increment a single atomic_t in acc->collector, and when
	29	* the rescale function runs it resets the atomic counter to 0 and adds its
	30	* old value to each of the exported numbers.
	31	*
	32	* To reduce rounding error, the numbers in struct cache_stats are all
	33	* stored left shifted by 16, and scaled back in the sysfs show() function.
	34	*/
	35
	36	static const unsigned DAY_RESCALE = 288;
	37	static const unsigned HOUR_RESCALE = 12;
	38	static const unsigned FIVE_MINUTE_RESCALE = 1;
	39	static const unsigned accounting_delay = (HZ * 300) / 22;
	40	static const unsigned accounting_weight = 32;
	41
	42	/* sysfs reading/writing */
	43
	44	read_attribute(cache_hits);
	45	read_attribute(cache_misses);
	46	read_attribute(cache_bypass_hits);
	47	read_attribute(cache_bypass_misses);
	48	read_attribute(cache_hit_ratio);
	49	read_attribute(cache_readaheads);
	50	read_attribute(cache_miss_collisions);
	51	read_attribute(bypassed);
	52
	53	SHOW(bch_stats)
	54	{
	55	struct cache_stats *s =
	56	container_of(kobj, struct cache_stats, kobj);
	57	#define var(stat) (s->stat >> 16)
	58	var_print(cache_hits);
	59	var_print(cache_misses);
	60	var_print(cache_bypass_hits);
	61	var_print(cache_bypass_misses);
	62
	63	sysfs_print(cache_hit_ratio,
	64	DIV_SAFE(var(cache_hits) * 100,
	65	var(cache_hits) + var(cache_misses)));
	66
	67	var_print(cache_readaheads);
	68	var_print(cache_miss_collisions);
	69	sysfs_hprint(bypassed, var(sectors_bypassed) << 9);
	70	#undef var
	71	return 0;
	72	}
	73
	74	STORE(bch_stats)
75	{
76	return size;
77	}
78
79	static void bch_stats_release(struct kobject *k)
80	{
81	}
82
83	static struct attribute *bch_stats_files[] = {
84	&sysfs_cache_hits,
85	&sysfs_cache_misses,
86	&sysfs_cache_bypass_hits,
87	&sysfs_cache_bypass_misses,
88	&sysfs_cache_hit_ratio,
89	&sysfs_cache_readaheads,
90	&sysfs_cache_miss_collisions,
91	&sysfs_bypassed,
92	NULL
93	};
94	static KTYPE(bch_stats);
95
cafe5635 KO	96	int bch_cache_accounting_add_kobjs(struct cache_accounting *acc,
	97	struct kobject *parent)
	98	{
	99	int ret = kobject_add(&acc->total.kobj, parent,
	100	"stats_total");
	101	ret = ret ?: kobject_add(&acc->five_minute.kobj, parent,
	102	"stats_five_minute");
	103	ret = ret ?: kobject_add(&acc->hour.kobj, parent,
	104	"stats_hour");
	105	ret = ret ?: kobject_add(&acc->day.kobj, parent,
	106	"stats_day");
	107	return ret;
	108	}
	109
	110	void bch_cache_accounting_clear(struct cache_accounting *acc)
	111	{
	112	memset(&acc->total.cache_hits,
	113	0,
	114	sizeof(unsigned long) * 7);
	115	}
	116
	117	void bch_cache_accounting_destroy(struct cache_accounting *acc)
	118	{
	119	kobject_put(&acc->total.kobj);
	120	kobject_put(&acc->five_minute.kobj);
	121	kobject_put(&acc->hour.kobj);
	122	kobject_put(&acc->day.kobj);
	123
	124	atomic_set(&acc->closing, 1);
	125	if (del_timer_sync(&acc->timer))
	126	closure_return(&acc->cl);
	127	}
	128
	129	/* EWMA scaling */
	130
	131	static void scale_stat(unsigned long *stat)
	132	{
	133	stat = ewma_add(stat, 0, accounting_weight, 0);
	134	}
	135
	136	static void scale_stats(struct cache_stats *stats, unsigned long rescale_at)
	137	{
	138	if (++stats->rescale == rescale_at) {
	139	stats->rescale = 0;
	140	scale_stat(&stats->cache_hits);
	141	scale_stat(&stats->cache_misses);
	142	scale_stat(&stats->cache_bypass_hits);
	143	scale_stat(&stats->cache_bypass_misses);
	144	scale_stat(&stats->cache_readaheads);
	145	scale_stat(&stats->cache_miss_collisions);
	146	scale_stat(&stats->sectors_bypassed);
	147	}
	148	}
	149
	150	static void scale_accounting(unsigned long data)
	151	{
	152	struct cache_accounting acc = (struct cache_accounting ) data;
	153
	154	#define move_stat(name) do { \
	155	unsigned t = atomic_xchg(&acc->collector.name, 0); \
	156	t <<= 16; \
	157	acc->five_minute.name += t; \
	158	acc->hour.name += t; \
	159	acc->day.name += t; \
160	acc->total.name += t; \
161	} while (0)
162
163	move_stat(cache_hits);
164	move_stat(cache_misses);
165	move_stat(cache_bypass_hits);
166	move_stat(cache_bypass_misses);
167	move_stat(cache_readaheads);
168	move_stat(cache_miss_collisions);
169	move_stat(sectors_bypassed);
170
171	scale_stats(&acc->total, 0);
172	scale_stats(&acc->day, DAY_RESCALE);
173	scale_stats(&acc->hour, HOUR_RESCALE);
174	scale_stats(&acc->five_minute, FIVE_MINUTE_RESCALE);
175
176	acc->timer.expires += accounting_delay;
177
178	if (!atomic_read(&acc->closing))
179	add_timer(&acc->timer);
180	else
181	closure_return(&acc->cl);
182	}
183
184	static void mark_cache_stats(struct cache_stat_collector *stats,
185	bool hit, bool bypass)
186	{
187	if (!bypass)
188	if (hit)
189	atomic_inc(&stats->cache_hits);
190	else
191	atomic_inc(&stats->cache_misses);
192	else
193	if (hit)
194	atomic_inc(&stats->cache_bypass_hits);
195	else
196	atomic_inc(&stats->cache_bypass_misses);
197	}
198
220bb38c KO	199	void bch_mark_cache_accounting(struct cache_set c, struct bcache_device d,
220bb38c KO	200	bool hit, bool bypass)
cafe5635	201	{
220bb38c	202	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
cafe5635	203	mark_cache_stats(&dc->accounting.collector, hit, bypass);
220bb38c	204	mark_cache_stats(&c->accounting.collector, hit, bypass);
cafe5635 KO	205	}
cafe5635 KO	206
220bb38c	207	void bch_mark_cache_readahead(struct cache_set c, struct bcache_device d)
cafe5635	208	{
220bb38c	209	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
cafe5635	210	atomic_inc(&dc->accounting.collector.cache_readaheads);
220bb38c	211	atomic_inc(&c->accounting.collector.cache_readaheads);
cafe5635 KO	212	}
cafe5635 KO	213
220bb38c	214	void bch_mark_cache_miss_collision(struct cache_set c, struct bcache_device d)
cafe5635	215	{
220bb38c	216	struct cached_dev *dc = container_of(d, struct cached_dev, disk);
cafe5635	217	atomic_inc(&dc->accounting.collector.cache_miss_collisions);
220bb38c	218	atomic_inc(&c->accounting.collector.cache_miss_collisions);
cafe5635 KO	219	}
cafe5635 KO	220
220bb38c KO	221	void bch_mark_sectors_bypassed(struct cache_set c, struct cached_dev dc,
220bb38c KO	222	int sectors)
cafe5635	223	{
cafe5635	224	atomic_add(sectors, &dc->accounting.collector.sectors_bypassed);
220bb38c	225	atomic_add(sectors, &c->accounting.collector.sectors_bypassed);
cafe5635	226	}
f59fce84 KO	227
	228	void bch_cache_accounting_init(struct cache_accounting *acc,
	229	struct closure *parent)
	230	{
	231	kobject_init(&acc->total.kobj, &bch_stats_ktype);
	232	kobject_init(&acc->five_minute.kobj, &bch_stats_ktype);
	233	kobject_init(&acc->hour.kobj, &bch_stats_ktype);
	234	kobject_init(&acc->day.kobj, &bch_stats_ktype);
	235
	236	closure_init(&acc->cl, parent);
	237	init_timer(&acc->timer);
	238	acc->timer.expires = jiffies + accounting_delay;
	239	acc->timer.data = (unsigned long) acc;
	240	acc->timer.function = scale_accounting;
	241	add_timer(&acc->timer);
	242	}