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// 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"
/* disable automatic switching to percpu mode */
#define TIME_STATS_NONPCPU ((unsigned long) 1)
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 ((unsigned long) stats->buffer <= TIME_STATS_NONPCPU) {
spin_lock_irqsave(&stats->lock, flags);
time_stats_update_one(stats, start, end);
if (!stats->buffer &&
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_reset(struct bch2_time_stats *stats)
{
spin_lock_irq(&stats->lock);
unsigned offset = offsetof(struct bch2_time_stats, min_duration);
memset((void *) stats + offset, 0, sizeof(*stats) - offset);
if ((unsigned long) stats->buffer > TIME_STATS_NONPCPU) {
int cpu;
for_each_possible_cpu(cpu)
per_cpu_ptr(stats->buffer, cpu)->nr = 0;
}
spin_unlock_irq(&stats->lock);
}
void bch2_time_stats_exit(struct bch2_time_stats *stats)
{
if ((unsigned long) stats->buffer > TIME_STATS_NONPCPU)
free_percpu(stats->buffer);
stats->buffer = NULL;
}
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);
}
void bch2_time_stats_init_no_pcpu(struct bch2_time_stats *stats)
{
bch2_time_stats_init(stats);
stats->buffer = (struct time_stat_buffer __percpu *) TIME_STATS_NONPCPU;
}
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