Commit c46261de authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds

lockstat: human readability tweaks

Present all this fancy new lock statistics information:

*warning, _wide_ output ahead*

(output edited for purpose of brevity)

 # cat /proc/lock_stat
lock_stat version 0.1
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
                              class name    contentions   waittime-min   waittime-max waittime-total   acquisitions   holdtime-min   holdtime-max holdtime-total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------

                         &inode->i_mutex:         14458           6.57      398832.75     2469412.23        6768876           0.34    11398383.65   339410830.89
                         ---------------
                         &inode->i_mutex           4486          [<ffffffff802a08f9>] pipe_wait+0x86/0x8d
                         &inode->i_mutex              0          [<ffffffff802a01e8>] pipe_write_fasync+0x29/0x5d
                         &inode->i_mutex              0          [<ffffffff802a0e18>] pipe_read+0x74/0x3a5
                         &inode->i_mutex              0          [<ffffffff802a1a6a>] do_lookup+0x81/0x1ae

.................................................................................................................................................................

              &inode->i_data.tree_lock-W:           491           0.27          62.47         493.89        2477833           0.39         468.89     1146584.25
              &inode->i_data.tree_lock-R:            65           0.44           4.27          48.78       26288792           0.36         184.62    10197458.24
              --------------------------
                &inode->i_data.tree_lock             46          [<ffffffff80277095>] __do_page_cache_readahead+0x69/0x24f
                &inode->i_data.tree_lock             31          [<ffffffff8026f9fb>] add_to_page_cache+0x31/0xba
                &inode->i_data.tree_lock              0          [<ffffffff802770ee>] __do_page_cache_readahead+0xc2/0x24f
                &inode->i_data.tree_lock              0          [<ffffffff8026f6e4>] find_get_page+0x1a/0x58

.................................................................................................................................................................

                      proc_inum_idr.lock:             0           0.00           0.00           0.00             36           0.00          65.60         148.26
                        proc_subdir_lock:             0           0.00           0.00           0.00        3049859           0.00         106.81     1563212.42
                        shrinker_rwsem-W:             0           0.00           0.00           0.00              5           0.00           1.73           3.68
                        shrinker_rwsem-R:             0           0.00           0.00           0.00            633           2.57         246.57       10909.76

'contentions' and 'acquisitions' are the number of such events measured (since
the last reset). The waittime- and holdtime- (min, max, total) numbers are
presented in microseconds.

If there are any contention points, the lock class is presented in the block
format (as i_mutex and tree_lock above), otherwise a single line of output is
presented.

The output is sorted on absolute number of contentions (read + write), this
should get the worst offenders presented first, so that:

 # grep : /proc/lock_stat | head

will quickly show who's bad.

The stats can be reset using:

 # echo 0 > /proc/lock_stat

[bunk@stusta.de: make 2 functions static]
[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarJason Baron <jbaron@redhat.com>
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f20786ff
...@@ -149,6 +149,50 @@ static void lock_time_inc(struct lock_time *lt, s64 time) ...@@ -149,6 +149,50 @@ static void lock_time_inc(struct lock_time *lt, s64 time)
lt->nr++; lt->nr++;
} }
static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
{
dst->min += src->min;
dst->max += src->max;
dst->total += src->total;
dst->nr += src->nr;
}
struct lock_class_stats lock_stats(struct lock_class *class)
{
struct lock_class_stats stats;
int cpu, i;
memset(&stats, 0, sizeof(struct lock_class_stats));
for_each_possible_cpu(cpu) {
struct lock_class_stats *pcs =
&per_cpu(lock_stats, cpu)[class - lock_classes];
for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
stats.contention_point[i] += pcs->contention_point[i];
lock_time_add(&pcs->read_waittime, &stats.read_waittime);
lock_time_add(&pcs->write_waittime, &stats.write_waittime);
lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
}
return stats;
}
void clear_lock_stats(struct lock_class *class)
{
int cpu;
for_each_possible_cpu(cpu) {
struct lock_class_stats *cpu_stats =
&per_cpu(lock_stats, cpu)[class - lock_classes];
memset(cpu_stats, 0, sizeof(struct lock_class_stats));
}
memset(class->contention_point, 0, sizeof(class->contention_point));
}
static struct lock_class_stats *get_lock_stats(struct lock_class *class) static struct lock_class_stats *get_lock_stats(struct lock_class *class)
{ {
return &get_cpu_var(lock_stats)[class - lock_classes]; return &get_cpu_var(lock_stats)[class - lock_classes];
......
...@@ -15,6 +15,10 @@ ...@@ -15,6 +15,10 @@
#include <linux/seq_file.h> #include <linux/seq_file.h>
#include <linux/kallsyms.h> #include <linux/kallsyms.h>
#include <linux/debug_locks.h> #include <linux/debug_locks.h>
#include <linux/vmalloc.h>
#include <linux/sort.h>
#include <asm/uaccess.h>
#include <asm/div64.h>
#include "lockdep_internals.h" #include "lockdep_internals.h"
...@@ -344,6 +348,262 @@ static const struct file_operations proc_lockdep_stats_operations = { ...@@ -344,6 +348,262 @@ static const struct file_operations proc_lockdep_stats_operations = {
.release = seq_release, .release = seq_release,
}; };
#ifdef CONFIG_LOCK_STAT
struct lock_stat_data {
struct lock_class *class;
struct lock_class_stats stats;
};
struct lock_stat_seq {
struct lock_stat_data *iter;
struct lock_stat_data *iter_end;
struct lock_stat_data stats[MAX_LOCKDEP_KEYS];
};
/*
* sort on absolute number of contentions
*/
static int lock_stat_cmp(const void *l, const void *r)
{
const struct lock_stat_data *dl = l, *dr = r;
unsigned long nl, nr;
nl = dl->stats.read_waittime.nr + dl->stats.write_waittime.nr;
nr = dr->stats.read_waittime.nr + dr->stats.write_waittime.nr;
return nr - nl;
}
static void seq_line(struct seq_file *m, char c, int offset, int length)
{
int i;
for (i = 0; i < offset; i++)
seq_puts(m, " ");
for (i = 0; i < length; i++)
seq_printf(m, "%c", c);
seq_puts(m, "\n");
}
static void snprint_time(char *buf, size_t bufsiz, s64 nr)
{
unsigned long rem;
rem = do_div(nr, 1000); /* XXX: do_div_signed */
snprintf(buf, bufsiz, "%lld.%02d", (long long)nr, ((int)rem+5)/10);
}
static void seq_time(struct seq_file *m, s64 time)
{
char num[15];
snprint_time(num, sizeof(num), time);
seq_printf(m, " %14s", num);
}
static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
{
seq_printf(m, "%14lu", lt->nr);
seq_time(m, lt->min);
seq_time(m, lt->max);
seq_time(m, lt->total);
}
static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
{
char name[39];
struct lock_class *class;
struct lock_class_stats *stats;
int i, namelen;
class = data->class;
stats = &data->stats;
snprintf(name, 38, "%s", class->name);
namelen = strlen(name);
if (stats->write_holdtime.nr) {
if (stats->read_holdtime.nr)
seq_printf(m, "%38s-W:", name);
else
seq_printf(m, "%40s:", name);
seq_lock_time(m, &stats->write_waittime);
seq_puts(m, " ");
seq_lock_time(m, &stats->write_holdtime);
seq_puts(m, "\n");
}
if (stats->read_holdtime.nr) {
seq_printf(m, "%38s-R:", name);
seq_lock_time(m, &stats->read_waittime);
seq_puts(m, " ");
seq_lock_time(m, &stats->read_holdtime);
seq_puts(m, "\n");
}
if (stats->read_waittime.nr + stats->write_waittime.nr == 0)
return;
if (stats->read_holdtime.nr)
namelen += 2;
for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {
char sym[KSYM_SYMBOL_LEN];
char ip[32];
if (class->contention_point[i] == 0)
break;
if (!i)
seq_line(m, '-', 40-namelen, namelen);
sprint_symbol(sym, class->contention_point[i]);
snprintf(ip, sizeof(ip), "[<%p>]",
(void *)class->contention_point[i]);
seq_printf(m, "%40s %14lu %29s %s\n", name,
stats->contention_point[i],
ip, sym);
}
if (i) {
seq_puts(m, "\n");
seq_line(m, '.', 0, 40 + 1 + 8 * (14 + 1));
seq_puts(m, "\n");
}
}
static void seq_header(struct seq_file *m)
{
seq_printf(m, "lock_stat version 0.1\n");
seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1));
seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s\n",
"class name",
"contentions",
"waittime-min",
"waittime-max",
"waittime-total",
"acquisitions",
"holdtime-min",
"holdtime-max",
"holdtime-total");
seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1));
seq_printf(m, "\n");
}
static void *ls_start(struct seq_file *m, loff_t *pos)
{
struct lock_stat_seq *data = m->private;
if (data->iter == data->stats)
seq_header(m);
return data->iter;
}
static void *ls_next(struct seq_file *m, void *v, loff_t *pos)
{
struct lock_stat_seq *data = m->private;
(*pos)++;
data->iter = v;
data->iter++;
if (data->iter == data->iter_end)
data->iter = NULL;
return data->iter;
}
static void ls_stop(struct seq_file *m, void *v)
{
}
static int ls_show(struct seq_file *m, void *v)
{
struct lock_stat_seq *data = m->private;
seq_stats(m, data->iter);
return 0;
}
static struct seq_operations lockstat_ops = {
.start = ls_start,
.next = ls_next,
.stop = ls_stop,
.show = ls_show,
};
static int lock_stat_open(struct inode *inode, struct file *file)
{
int res;
struct lock_class *class;
struct lock_stat_seq *data = vmalloc(sizeof(struct lock_stat_seq));
if (!data)
return -ENOMEM;
res = seq_open(file, &lockstat_ops);
if (!res) {
struct lock_stat_data *iter = data->stats;
struct seq_file *m = file->private_data;
data->iter = iter;
list_for_each_entry(class, &all_lock_classes, lock_entry) {
iter->class = class;
iter->stats = lock_stats(class);
iter++;
}
data->iter_end = iter;
sort(data->stats, data->iter_end - data->iter,
sizeof(struct lock_stat_data),
lock_stat_cmp, NULL);
m->private = data;
} else
vfree(data);
return res;
}
static ssize_t lock_stat_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct lock_class *class;
char c;
if (count) {
if (get_user(c, buf))
return -EFAULT;
if (c != '0')
return count;
list_for_each_entry(class, &all_lock_classes, lock_entry)
clear_lock_stats(class);
}
return count;
}
static int lock_stat_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
vfree(seq->private);
seq->private = NULL;
return seq_release(inode, file);
}
static const struct file_operations proc_lock_stat_operations = {
.open = lock_stat_open,
.write = lock_stat_write,
.read = seq_read,
.llseek = seq_lseek,
.release = lock_stat_release,
};
#endif /* CONFIG_LOCK_STAT */
static int __init lockdep_proc_init(void) static int __init lockdep_proc_init(void)
{ {
struct proc_dir_entry *entry; struct proc_dir_entry *entry;
...@@ -356,6 +616,12 @@ static int __init lockdep_proc_init(void) ...@@ -356,6 +616,12 @@ static int __init lockdep_proc_init(void)
if (entry) if (entry)
entry->proc_fops = &proc_lockdep_stats_operations; entry->proc_fops = &proc_lockdep_stats_operations;
#ifdef CONFIG_LOCK_STAT
entry = create_proc_entry("lock_stat", S_IRUSR, NULL);
if (entry)
entry->proc_fops = &proc_lock_stat_operations;
#endif
return 0; return 0;
} }
......
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