[linux-2.6-block.git] / drivers / md / bcache / stats.c

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