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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-07-19 01:49:00 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 10:04:49 -0700
commit96645678cd726e87ce42a0664de71e047e32bca4 (patch)
tree116f568a090414777b481e8e5d9db55f420e4335 /kernel
parent443aef0eddfa44c158d1b94ebb431a70638fcab4 (diff)
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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: 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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/lockdep.c38
-rw-r--r--kernel/lockdep_proc.c19
-rw-r--r--kernel/mutex.c2
3 files changed, 39 insertions, 20 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index cb64022851c8..156fce4960c3 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -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->write_holdtime, &stats.write_holdtime);
+
+ for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
+ stats.bounces[i] += pcs->bounces[i];
}
return stats;
@@ -2325,6 +2328,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
lock->name = name;
lock->key = key;
lock->class_cache = NULL;
+#ifdef CONFIG_LOCK_STAT
+ lock->cpu = raw_smp_processor_id();
+#endif
if (subclass)
register_lock_class(lock, subclass, 1);
}
@@ -2775,6 +2781,8 @@ found_it:
stats = get_lock_stats(hlock->class);
if (point < ARRAY_SIZE(stats->contention_point))
stats->contention_point[i]++;
+ if (lock->cpu != smp_processor_id())
+ stats->bounces[bounce_contended + !!hlock->read]++;
put_lock_stats(stats);
}
@@ -2786,8 +2794,8 @@ __lock_acquired(struct lockdep_map *lock)
struct lock_class_stats *stats;
unsigned int depth;
u64 now;
- s64 waittime;
- int i;
+ s64 waittime = 0;
+ int i, cpu;
depth = curr->lockdep_depth;
if (DEBUG_LOCKS_WARN_ON(!depth))
@@ -2809,19 +2817,25 @@ __lock_acquired(struct lockdep_map *lock)
return;
found_it:
- if (!hlock->waittime_stamp)
- return;
-
- now = sched_clock();
- waittime = now - hlock->waittime_stamp;
- hlock->holdtime_stamp = now;
+ cpu = smp_processor_id();
+ if (hlock->waittime_stamp) {
+ now = sched_clock();
+ waittime = now - hlock->waittime_stamp;
+ hlock->holdtime_stamp = now;
+ }
stats = get_lock_stats(hlock->class);
- if (hlock->read)
- lock_time_inc(&stats->read_waittime, waittime);
- else
- lock_time_inc(&stats->write_waittime, waittime);
+ if (waittime) {
+ if (hlock->read)
+ lock_time_inc(&stats->read_waittime, waittime);
+ else
+ lock_time_inc(&stats->write_waittime, waittime);
+ }
+ if (lock->cpu != cpu)
+ stats->bounces[bounce_acquired + !!hlock->read]++;
put_lock_stats(stats);
+
+ lock->cpu = cpu;
}
void lock_contended(struct lockdep_map *lock, unsigned long ip)
diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index 39163ed1bf0a..7ff80135cbeb 100644
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -430,16 +430,18 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
else
seq_printf(m, "%40s:", name);
+ seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
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_puts(m, "\n");
}
if (stats->read_holdtime.nr) {
seq_printf(m, "%38s-R:", name);
+ seq_printf(m, "%14lu ", stats->bounces[bounce_contended_read]);
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_puts(m, "\n");
}
@@ -469,26 +471,29 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
}
if (i) {
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");
}
}
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",
+ seq_printf(m, "lock_stat version 0.2\n");
+ seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
+ seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
+ "%14s %14s\n",
"class name",
+ "con-bounces",
"contentions",
"waittime-min",
"waittime-max",
"waittime-total",
+ "acq-bounces",
"acquisitions",
"holdtime-min",
"holdtime-max",
"holdtime-total");
- seq_line(m, '-', 0, 40 + 1 + 8 * (14 + 1));
+ seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
seq_printf(m, "\n");
}
diff --git a/kernel/mutex.c b/kernel/mutex.c
index 7a3f32761f26..691b86564dd9 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -180,8 +180,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass)
spin_lock_mutex(&lock->wait_lock, flags);
}
- lock_acquired(&lock->dep_map);
done:
+ lock_acquired(&lock->dep_map);
/* got the lock - rejoice! */
mutex_remove_waiter(lock, &waiter, task_thread_info(task));
debug_mutex_set_owner(lock, task_thread_info(task));