locking/lockdep: Make global debug_locks* variables read-mostly

Make the frequently used lockdep global variable debug_locks read-mostly.
As debug_locks_silent is sometime used together with debug_locks,
it is also made read-mostly so that they can be close together.

With false cacheline sharing, cacheline contention problem can happen
depending on what get put into the same cacheline as debug_locks.

Signed-off-by: Waiman Long <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index 120225e9a366ba2c34658e0dc6e4fd6da52878a7..257ab3c92cb8ad5b78f88f8eb81974f550c657c3 100644 (file)
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -8,8 +8,8 @@
 
 struct task_struct;
 
-extern int debug_locks;
-extern int debug_locks_silent;
+extern int debug_locks __read_mostly;
+extern int debug_locks_silent __read_mostly;
 
 
 static inline int __debug_locks_off(void)

diff --git a/lib/debug_locks.c b/lib/debug_locks.c
index 124fdf238b3d95739292424ef40c12b6b3c22308..ce51749cc145f22e1ffbd2f5d22867f33b1b25cb 100644 (file)
--- a/lib/debug_locks.c
+++ b/lib/debug_locks.c
@@ -21,7 +21,7 @@
  * that would just muddy the log. So we report the first one and
  * shut up after that.
  */
-int debug_locks = 1;
+int debug_locks __read_mostly = 1;
 EXPORT_SYMBOL_GPL(debug_locks);
 
 /*
@@ -29,7 +29,7 @@ EXPORT_SYMBOL_GPL(debug_locks);
  * 'silent failure': nothing is printed to the console when
  * a locking bug is detected.
  */
-int debug_locks_silent;
+int debug_locks_silent __read_mostly;
 EXPORT_SYMBOL_GPL(debug_locks_silent);
 
 /*