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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-07-19 04:49:00 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 13:04:49 -0400
commit96645678cd726e87ce42a0664de71e047e32bca4 (patch)
tree116f568a090414777b481e8e5d9db55f420e4335 /kernel/lockdep.c
parent443aef0eddfa44c158d1b94ebb431a70638fcab4 (diff)
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/lockdep.c')
-rw-r--r--kernel/lockdep.c38
1 files changed, 26 insertions, 12 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)
177 177
178 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); 178 lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
179 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); 179 lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
180
181 for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
182 stats.bounces[i] += pcs->bounces[i];
180 } 183 }
181 184
182 return stats; 185 return stats;
@@ -2325,6 +2328,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
2325 lock->name = name; 2328 lock->name = name;
2326 lock->key = key; 2329 lock->key = key;
2327 lock->class_cache = NULL; 2330 lock->class_cache = NULL;
2331#ifdef CONFIG_LOCK_STAT
2332 lock->cpu = raw_smp_processor_id();
2333#endif
2328 if (subclass) 2334 if (subclass)
2329 register_lock_class(lock, subclass, 1); 2335 register_lock_class(lock, subclass, 1);
2330} 2336}
@@ -2775,6 +2781,8 @@ found_it:
2775 stats = get_lock_stats(hlock->class); 2781 stats = get_lock_stats(hlock->class);
2776 if (point < ARRAY_SIZE(stats->contention_point)) 2782 if (point < ARRAY_SIZE(stats->contention_point))
2777 stats->contention_point[i]++; 2783 stats->contention_point[i]++;
2784 if (lock->cpu != smp_processor_id())
2785 stats->bounces[bounce_contended + !!hlock->read]++;
2778 put_lock_stats(stats); 2786 put_lock_stats(stats);
2779} 2787}
2780 2788
@@ -2786,8 +2794,8 @@ __lock_acquired(struct lockdep_map *lock)
2786 struct lock_class_stats *stats; 2794 struct lock_class_stats *stats;
2787 unsigned int depth; 2795 unsigned int depth;
2788 u64 now; 2796 u64 now;
2789 s64 waittime; 2797 s64 waittime = 0;
2790 int i; 2798 int i, cpu;
2791 2799
2792 depth = curr->lockdep_depth; 2800 depth = curr->lockdep_depth;
2793 if (DEBUG_LOCKS_WARN_ON(!depth)) 2801 if (DEBUG_LOCKS_WARN_ON(!depth))
@@ -2809,19 +2817,25 @@ __lock_acquired(struct lockdep_map *lock)
2809 return; 2817 return;
2810 2818
2811found_it: 2819found_it:
2812 if (!hlock->waittime_stamp) 2820 cpu = smp_processor_id();
2813 return; 2821 if (hlock->waittime_stamp) {
2814 2822 now = sched_clock();
2815 now = sched_clock(); 2823 waittime = now - hlock->waittime_stamp;
2816 waittime = now - hlock->waittime_stamp; 2824 hlock->holdtime_stamp = now;
2817 hlock->holdtime_stamp = now; 2825 }
2818 2826
2819 stats = get_lock_stats(hlock->class); 2827 stats = get_lock_stats(hlock->class);
2820 if (hlock->read) 2828 if (waittime) {
2821 lock_time_inc(&stats->read_waittime, waittime); 2829 if (hlock->read)
2822 else 2830 lock_time_inc(&stats->read_waittime, waittime);
2823 lock_time_inc(&stats->write_waittime, waittime); 2831 else
2832 lock_time_inc(&stats->write_waittime, waittime);
2833 }
2834 if (lock->cpu != cpu)
2835 stats->bounces[bounce_acquired + !!hlock->read]++;
2824 put_lock_stats(stats); 2836 put_lock_stats(stats);
2837
2838 lock->cpu = cpu;
2825} 2839}
2826 2840
2827void lock_contended(struct lockdep_map *lock, unsigned long ip) 2841void lock_contended(struct lockdep_map *lock, unsigned long ip)