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>
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 3d3386b..0e843bf 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -130,12 +130,24 @@
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 {
unsigned long contention_point[4];
struct lock_time read_waittime;
struct lock_time write_waittime;
struct lock_time read_holdtime;
struct lock_time write_holdtime;
+ unsigned long bounces[nr_bounce_types];
};
struct lock_class_stats lock_stats(struct lock_class *class);
@@ -150,6 +162,9 @@
struct lock_class_key *key;
struct lock_class *class_cache;
const char *name;
+#ifdef CONFIG_LOCK_STAT
+ int cpu;
+#endif
};
/*
@@ -321,8 +336,8 @@
if (!try(_lock)) { \
lock_contended(&(_lock)->dep_map, _RET_IP_); \
lock(_lock); \
- lock_acquired(&(_lock)->dep_map); \
} \
+ lock_acquired(&(_lock)->dep_map); \
} while (0)
#else /* CONFIG_LOCK_STAT */