linux-stable/fs/bcachefs/time_stats.c
Darrick J. Wong 273960b8f3 bcachefs: time_stats: split stats-with-quantiles into a separate structure
Currently, struct time_stats has the optional ability to quantize the
information that it collects.  This is /probably/ useful for callers who
want to see quantized information, but it more than doubles the size of
the structure from 224 bytes to 464.  For users who don't care about
that (e.g. upcoming xfs patches) and want to avoid wasting 240 bytes per
counter, split the two into separate pieces.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-03-13 21:38:01 -04:00

165 lines
4.2 KiB
C

// 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},
{ "d", (u64) NSEC_PER_SEC * 3600 * 24},
{ "w", (u64) NSEC_PER_SEC * 3600 * 24 * 7},
{ "y", (u64) NSEC_PER_SEC * ((3600 * 24 * 7 * 365) + (3600 * (24 / 4) * 7))}, /* 365.25d */
{ "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;
bool initted = stats->last_event != 0;
if (time_after64(end, start)) {
struct quantiles *quantiles = time_stats_to_quantiles(stats);
duration = end - start;
mean_and_variance_update(&stats->duration_stats, duration);
mean_and_variance_weighted_update(&stats->duration_stats_weighted,
duration, initted, TIME_STATS_MV_WEIGHT);
stats->max_duration = max(stats->max_duration, duration);
stats->min_duration = min(stats->min_duration, duration);
stats->total_duration += duration;
if (quantiles)
quantiles_update(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, initted, TIME_STATS_MV_WEIGHT);
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;
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, TIME_STATS_MV_WEIGHT) < 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->min_duration = U64_MAX;
stats->min_freq = U64_MAX;
spin_lock_init(&stats->lock);
}