Commit 96645678 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds

lockstat: measure lock bouncing

    __acquire
        |
       lock _____
        |        \
        |    __contended
        |         |
        |        wait
        | _______/
        |/
        |
   __acquired
        |
   __release
        |
     unlock

We measure acquisition and contention bouncing.

This is done by recording a cpu stamp in each lock instance.

Contention bouncing requires the cpu stamp to be set on acquisition. Hence we
move __acquired into the generic path.

__acquired is then used to measure acquisition bouncing by comparing the
current cpu with the old stamp before replacing it.

__contended is used to measure contention bouncing (only useful for preemptable
locks)

[akpm@linux-foundation.org: cleanups]
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 443aef0e
...@@ -130,12 +130,24 @@ struct lock_time { ...@@ -130,12 +130,24 @@ struct lock_time {
unsigned long nr; unsigned long nr;
}; };
enum bounce_type {
bounce_acquired_write,
bounce_acquired_read,
bounce_contended_write,
bounce_contended_read,
nr_bounce_types,
bounce_acquired = bounce_acquired_write,
bounce_contended = bounce_contended_write,
};
struct lock_class_stats { struct lock_class_stats {
unsigned long contention_point[4]; unsigned long contention_point[4];
struct lock_time read_waittime; struct lock_time read_waittime;
struct lock_time write_waittime; struct lock_time write_waittime;
struct lock_time read_holdtime; struct lock_time read_holdtime;
struct lock_time write_holdtime; struct lock_time write_holdtime;
unsigned long bounces[nr_bounce_types];
}; };
struct lock_class_stats lock_stats(struct lock_class *class); struct lock_class_stats lock_stats(struct lock_class *class);
...@@ -150,6 +162,9 @@ struct lockdep_map { ...@@ -150,6 +162,9 @@ struct lockdep_map {
struct lock_class_key *key; struct lock_class_key *key;
struct lock_class *class_cache; struct lock_class *class_cache;
const char *name; const char *name;
#ifdef CONFIG_LOCK_STAT
int cpu;
#endif
}; };
/* /*
...@@ -321,8 +336,8 @@ do { \ ...@@ -321,8 +336,8 @@ do { \
if (!try(_lock)) { \ if (!try(_lock)) { \
lock_contended(&(_lock)->dep_map, _RET_IP_); \ lock_contended(&(_lock)->dep_map, _RET_IP_); \
lock(_lock); \ lock(_lock); \
lock_acquired(&(_lock)->dep_map); \
} \ } \
lock_acquired(&(_lock)->dep_map); \
} while (0) } while (0)
#else /* CONFIG_LOCK_STAT */ #else /* CONFIG_LOCK_STAT */
......
...@@ -177,6 +177,9 @@ struct lock_class_stats lock_stats(struct lock_class *class) ...@@ -177,6 +177,9 @@ struct lock_class_stats lock_stats(struct lock_class *class)
lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
stats.bounces[i] += pcs->bounces[i];
} }
return stats; return stats;
...@@ -2325,6 +2328,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name, ...@@ -2325,6 +2328,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
lock->name = name; lock->name = name;
lock->key = key; lock->key = key;
lock->class_cache = NULL; lock->class_cache = NULL;
#ifdef CONFIG_LOCK_STAT
lock->cpu = raw_smp_processor_id();
#endif
if (subclass) if (subclass)
register_lock_class(lock, subclass, 1); register_lock_class(lock, subclass, 1);
} }
...@@ -2775,6 +2781,8 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip) ...@@ -2775,6 +2781,8 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
stats = get_lock_stats(hlock->class); stats = get_lock_stats(hlock->class);
if (point < ARRAY_SIZE(stats->contention_point)) if (point < ARRAY_SIZE(stats->contention_point))
stats->contention_point[i]++; stats->contention_point[i]++;
if (lock->cpu != smp_processor_id())
stats->bounces[bounce_contended + !!hlock->read]++;
put_lock_stats(stats); put_lock_stats(stats);
} }
...@@ -2786,8 +2794,8 @@ __lock_acquired(struct lockdep_map *lock) ...@@ -2786,8 +2794,8 @@ __lock_acquired(struct lockdep_map *lock)
struct lock_class_stats *stats; struct lock_class_stats *stats;
unsigned int depth; unsigned int depth;
u64 now; u64 now;
s64 waittime; s64 waittime = 0;
int i; int i, cpu;
depth = curr->lockdep_depth; depth = curr->lockdep_depth;
if (DEBUG_LOCKS_WARN_ON(!depth)) if (DEBUG_LOCKS_WARN_ON(!depth))
...@@ -2809,19 +2817,25 @@ __lock_acquired(struct lockdep_map *lock) ...@@ -2809,19 +2817,25 @@ __lock_acquired(struct lockdep_map *lock)
return; return;
found_it: found_it:
if (!hlock->waittime_stamp) cpu = smp_processor_id();
return; if (hlock->waittime_stamp) {
now = sched_clock();
now = sched_clock(); waittime = now - hlock->waittime_stamp;
waittime = now - hlock->waittime_stamp; hlock->holdtime_stamp = now;
hlock->holdtime_stamp = now; }
stats = get_lock_stats(hlock->class); stats = get_lock_stats(hlock->class);
if (hlock->read) if (waittime) {
lock_time_inc(&stats->read_waittime, waittime); if (hlock->read)
else lock_time_inc(&stats->read_waittime, waittime);
lock_time_inc(&stats->write_waittime, waittime); else
lock_time_inc(&stats->write_waittime, waittime);
}
if (lock->cpu != cpu)
stats->bounces[bounce_acquired + !!hlock->read]++;
put_lock_stats(stats); put_lock_stats(stats);
lock->cpu = cpu;
} }
void lock_contended(struct lockdep_map *lock, unsigned long ip) void lock_contended(struct lockdep_map *lock, unsigned long ip)
......
...@@ -430,16 +430,18 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data) ...@@ -430,16 +430,18 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
else else
seq_printf(m, "%40s:", name); seq_printf(m, "%40s:", name);
seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
seq_lock_time(m, &stats->write_waittime); seq_lock_time(m, &stats->write_waittime);
seq_puts(m, " "); seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
seq_lock_time(m, &stats->write_holdtime); seq_lock_time(m, &stats->write_holdtime);
seq_puts(m, "\n"); seq_puts(m, "\n");
} }
if (stats->read_holdtime.nr) { if (stats->read_holdtime.nr) {
seq_printf(m, "%38s-R:", name); seq_printf(m, "%38s-R:", name);
seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
seq_lock_time(m, &stats->read_waittime); seq_lock_time(m, &stats->read_waittime);
seq_puts(m, " "); seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
seq_lock_time(m, &stats->read_holdtime); seq_lock_time(m, &stats->read_holdtime);
seq_puts(m, "\n"); seq_puts(m, "\n");
} }
...@@ -469,26 +471,29 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data) ...@@ -469,26 +471,29 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
} }
if (i) { if (i) {
seq_puts(m, "\n"); seq_puts(m, "\n");
seq_line(m, '.', 0, 40 + 1 + 8 * (14 + 1)); seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
seq_puts(m, "\n"); seq_puts(m, "\n");
} }
} }
static void seq_header(struct seq_file *m) static void seq_header(struct seq_file *m)
{ {
seq_printf(m, "lock_stat version 0.1\n"); seq_printf(m, "lock_stat version 0.2\n");
seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1)); seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s\n", seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
"%14s %14s\n",
"class name", "class name",
"con-bounces",
"contentions", "contentions",
"waittime-min", "waittime-min",
"waittime-max", "waittime-max",
"waittime-total", "waittime-total",
"acq-bounces",
"acquisitions", "acquisitions",
"holdtime-min", "holdtime-min",
"holdtime-max", "holdtime-max",
"holdtime-total"); "holdtime-total");
seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1)); seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
seq_printf(m, "\n"); seq_printf(m, "\n");
} }
......
...@@ -180,8 +180,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass) ...@@ -180,8 +180,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass)
spin_lock_mutex(&lock->wait_lock, flags); spin_lock_mutex(&lock->wait_lock, flags);
} }
lock_acquired(&lock->dep_map);
done: done:
lock_acquired(&lock->dep_map);
/* got the lock - rejoice! */ /* got the lock - rejoice! */
mutex_remove_waiter(lock, &waiter, task_thread_info(task)); mutex_remove_waiter(lock, &waiter, task_thread_info(task));
debug_mutex_set_owner(lock, task_thread_info(task)); debug_mutex_set_owner(lock, task_thread_info(task));
......
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