lockstat: measure lock bouncing
__acquire
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lock _____
| \
| __contended
| |
| wait
| _______/
|/
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__acquired
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__release
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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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra
Linus Torvalds
parent
443aef0edd
commit
96645678cd
4 changed files with 55 additions and 21 deletions
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@ -130,12 +130,24 @@ struct lock_time {
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unsigned long nr;
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};
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enum bounce_type {
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bounce_acquired_write,
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bounce_acquired_read,
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bounce_contended_write,
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bounce_contended_read,
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nr_bounce_types,
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bounce_acquired = bounce_acquired_write,
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bounce_contended = bounce_contended_write,
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};
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struct lock_class_stats {
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unsigned long contention_point[4];
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struct lock_time read_waittime;
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struct lock_time write_waittime;
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struct lock_time read_holdtime;
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struct lock_time write_holdtime;
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unsigned long bounces[nr_bounce_types];
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};
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struct lock_class_stats lock_stats(struct lock_class *class);
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@ -150,6 +162,9 @@ struct lockdep_map {
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struct lock_class_key *key;
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struct lock_class *class_cache;
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const char *name;
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#ifdef CONFIG_LOCK_STAT
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int cpu;
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#endif
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};
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/*
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@ -321,8 +336,8 @@ do { \
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if (!try(_lock)) { \
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lock_contended(&(_lock)->dep_map, _RET_IP_); \
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lock(_lock); \
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lock_acquired(&(_lock)->dep_map); \
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} \
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lock_acquired(&(_lock)->dep_map); \
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} while (0)
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#else /* CONFIG_LOCK_STAT */
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@ -177,6 +177,9 @@ struct lock_class_stats lock_stats(struct lock_class *class)
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lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
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lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
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for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
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stats.bounces[i] += pcs->bounces[i];
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}
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return stats;
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@ -2325,6 +2328,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
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lock->name = name;
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lock->key = key;
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lock->class_cache = NULL;
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#ifdef CONFIG_LOCK_STAT
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lock->cpu = raw_smp_processor_id();
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#endif
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if (subclass)
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register_lock_class(lock, subclass, 1);
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}
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@ -2775,6 +2781,8 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
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stats = get_lock_stats(hlock->class);
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if (point < ARRAY_SIZE(stats->contention_point))
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stats->contention_point[i]++;
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if (lock->cpu != smp_processor_id())
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stats->bounces[bounce_contended + !!hlock->read]++;
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put_lock_stats(stats);
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}
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@ -2786,8 +2794,8 @@ __lock_acquired(struct lockdep_map *lock)
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struct lock_class_stats *stats;
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unsigned int depth;
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u64 now;
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s64 waittime;
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int i;
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s64 waittime = 0;
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int i, cpu;
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depth = curr->lockdep_depth;
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if (DEBUG_LOCKS_WARN_ON(!depth))
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@ -2809,19 +2817,25 @@ __lock_acquired(struct lockdep_map *lock)
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return;
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found_it:
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if (!hlock->waittime_stamp)
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return;
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now = sched_clock();
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waittime = now - hlock->waittime_stamp;
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hlock->holdtime_stamp = now;
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cpu = smp_processor_id();
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if (hlock->waittime_stamp) {
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now = sched_clock();
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waittime = now - hlock->waittime_stamp;
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hlock->holdtime_stamp = now;
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}
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stats = get_lock_stats(hlock->class);
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if (hlock->read)
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lock_time_inc(&stats->read_waittime, waittime);
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else
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lock_time_inc(&stats->write_waittime, waittime);
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if (waittime) {
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if (hlock->read)
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lock_time_inc(&stats->read_waittime, waittime);
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else
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lock_time_inc(&stats->write_waittime, waittime);
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}
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if (lock->cpu != cpu)
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stats->bounces[bounce_acquired + !!hlock->read]++;
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put_lock_stats(stats);
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lock->cpu = cpu;
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}
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void lock_contended(struct lockdep_map *lock, unsigned long ip)
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@ -430,16 +430,18 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
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else
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seq_printf(m, "%40s:", name);
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seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
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seq_lock_time(m, &stats->write_waittime);
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seq_puts(m, " ");
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seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
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seq_lock_time(m, &stats->write_holdtime);
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seq_puts(m, "\n");
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}
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if (stats->read_holdtime.nr) {
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seq_printf(m, "%38s-R:", name);
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seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
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seq_lock_time(m, &stats->read_waittime);
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seq_puts(m, " ");
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seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_read]);
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seq_lock_time(m, &stats->read_holdtime);
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seq_puts(m, "\n");
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}
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@ -469,26 +471,29 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
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}
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if (i) {
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seq_puts(m, "\n");
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seq_line(m, '.', 0, 40 + 1 + 8 * (14 + 1));
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seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
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seq_puts(m, "\n");
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}
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}
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static void seq_header(struct seq_file *m)
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{
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seq_printf(m, "lock_stat version 0.1\n");
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seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1));
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seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s\n",
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seq_printf(m, "lock_stat version 0.2\n");
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seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
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seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
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"%14s %14s\n",
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"class name",
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"con-bounces",
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"contentions",
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"waittime-min",
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"waittime-max",
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"waittime-total",
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"acq-bounces",
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"acquisitions",
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"holdtime-min",
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"holdtime-max",
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"holdtime-total");
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seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1));
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seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
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seq_printf(m, "\n");
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}
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@ -180,8 +180,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass)
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spin_lock_mutex(&lock->wait_lock, flags);
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}
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lock_acquired(&lock->dep_map);
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done:
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lock_acquired(&lock->dep_map);
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/* got the lock - rejoice! */
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mutex_remove_waiter(lock, &waiter, task_thread_info(task));
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debug_mutex_set_owner(lock, task_thread_info(task));
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