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// SPDX-License-Identifier: GPL-2.0
#include <linux/eytzinger.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/time.h>
#include <linux/time_stats.h>
#include <linux/spinlock.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},
{ "eon", U64_MAX },
};
const struct time_unit *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;
}
EXPORT_SYMBOL_GPL(pick_time_units);
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 time_stats *stats,
u64 start, u64 end)
{
u64 duration, freq;
if (time_after64(end, start)) {
duration = end - start;
mean_and_variance_update(&stats->duration_stats, duration);
mean_and_variance_weighted_update(&stats->duration_stats_weighted, duration);
stats->max_duration = max(stats->max_duration, duration);
stats->min_duration = min(stats->min_duration, duration);
stats->total_duration += duration;
if (stats->quantiles_enabled)
quantiles_update(&stats->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);
stats->max_freq = max(stats->max_freq, freq);
stats->min_freq = min(stats->min_freq, freq);
}
stats->last_event = end;
}
void __time_stats_clear_buffer(struct 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;
}
EXPORT_SYMBOL_GPL(__time_stats_clear_buffer);
static noinline void time_stats_clear_buffer(struct time_stats *stats,
struct time_stat_buffer *b)
{
unsigned long flags;
spin_lock_irqsave(&stats->lock, flags);
__time_stats_clear_buffer(stats, b);
spin_unlock_irqrestore(&stats->lock, flags);
}
void __time_stats_update(struct time_stats *stats, u64 start, u64 end)
{
unsigned long flags;
WARN_ONCE(!stats->duration_stats_weighted.weight ||
!stats->freq_stats_weighted.weight,
"uninitialized time_stats");
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) < 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();
}
}
EXPORT_SYMBOL_GPL(__time_stats_update);
#include <linux/seq_buf.h>
static void seq_buf_time_units_aligned(struct seq_buf *out, u64 ns)
{
const struct time_unit *u = pick_time_units(ns);
seq_buf_printf(out, "%8llu %s", div64_u64(ns, u->nsecs), u->name);
}
void time_stats_to_seq_buf(struct seq_buf *out, struct time_stats *stats)
{
s64 f_mean = 0, d_mean = 0;
u64 f_stddev = 0, d_stddev = 0;
if (stats->buffer) {
int cpu;
spin_lock_irq(&stats->lock);
for_each_possible_cpu(cpu)
__time_stats_clear_buffer(stats, per_cpu_ptr(stats->buffer, cpu));
spin_unlock_irq(&stats->lock);
}
/*
* avoid divide by zero
*/
if (stats->freq_stats.n) {
f_mean = mean_and_variance_get_mean(stats->freq_stats);
f_stddev = mean_and_variance_get_stddev(stats->freq_stats);
d_mean = mean_and_variance_get_mean(stats->duration_stats);
d_stddev = mean_and_variance_get_stddev(stats->duration_stats);
}
seq_buf_printf(out, "count: %llu\n", stats->duration_stats.n);
seq_buf_printf(out, " since mount recent\n");
seq_buf_printf(out, "duration of events\n");
seq_buf_printf(out, " min: ");
seq_buf_time_units_aligned(out, stats->min_duration);
seq_buf_printf(out, "\n");
seq_buf_printf(out, " max: ");
seq_buf_time_units_aligned(out, stats->max_duration);
seq_buf_printf(out, "\n");
seq_buf_printf(out, " total: ");
seq_buf_time_units_aligned(out, stats->total_duration);
seq_buf_printf(out, "\n");
seq_buf_printf(out, " mean: ");
seq_buf_time_units_aligned(out, d_mean);
seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->duration_stats_weighted));
seq_buf_printf(out, "\n");
seq_buf_printf(out, " stddev: ");
seq_buf_time_units_aligned(out, d_stddev);
seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->duration_stats_weighted));
seq_buf_printf(out, "\n");
seq_buf_printf(out, "time between events\n");
seq_buf_printf(out, " min: ");
seq_buf_time_units_aligned(out, stats->min_freq);
seq_buf_printf(out, "\n");
seq_buf_printf(out, " max: ");
seq_buf_time_units_aligned(out, stats->max_freq);
seq_buf_printf(out, "\n");
seq_buf_printf(out, " mean: ");
seq_buf_time_units_aligned(out, f_mean);
seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_mean(stats->freq_stats_weighted));
seq_buf_printf(out, "\n");
seq_buf_printf(out, " stddev: ");
seq_buf_time_units_aligned(out, f_stddev);
seq_buf_time_units_aligned(out, mean_and_variance_weighted_get_stddev(stats->freq_stats_weighted));
seq_buf_printf(out, "\n");
if (stats->quantiles_enabled) {
int i = eytzinger0_first(NR_QUANTILES);
const struct time_unit *u =
pick_time_units(stats->quantiles.entries[i].m);
u64 last_q = 0;
seq_buf_printf(out, "quantiles (%s):\t", u->name);
eytzinger0_for_each(i, NR_QUANTILES) {
bool is_last = eytzinger0_next(i, NR_QUANTILES) == -1;
u64 q = max(stats->quantiles.entries[i].m, last_q);
seq_buf_printf(out, "%llu ", div_u64(q, u->nsecs));
if (is_last)
seq_buf_printf(out, "\n");
last_q = q;
}
}
}
EXPORT_SYMBOL_GPL(time_stats_to_seq_buf);
void time_stats_exit(struct time_stats *stats)
{
free_percpu(stats->buffer);
}
EXPORT_SYMBOL_GPL(time_stats_exit);
void time_stats_init(struct time_stats *stats)
{
memset(stats, 0, sizeof(*stats));
stats->duration_stats_weighted.weight = 8;
stats->freq_stats_weighted.weight = 8;
stats->min_duration = U64_MAX;
stats->min_freq = U64_MAX;
spin_lock_init(&stats->lock);
}
EXPORT_SYMBOL_GPL(time_stats_init);
MODULE_AUTHOR("Kent Overstreet");
MODULE_LICENSE("GPL");
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