[PATCH] lib/Kconfig.debug: add a comment to PROVE_LOCKING impact

[Lukasz Luba <l.luba@partner.samsung.com>]

This patch add some comment related to performance impact,
which can be really big (x3 times slower context switch).

Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 lib/Kconfig.debug | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 4966c4f..9e67a2a3 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1088,6 +1088,9 @@ config PROVE_LOCKING
 	 the proof of observed correctness is also maintained for an
 	 arbitrary combination of these separate locking variants.
 
+	 This feature enables LOCKDEP which can harm system performance
+	 even x3 times.
+
 	 For more details, see Documentation/locking/lockdep-design.txt.
 
 config LOCK_STAT
@@ -1112,6 +1115,10 @@ config LOCK_STAT
 	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 
+	 This feature enables LOCKDEP which can harm system performance
+	 even x3 times.
+	 For more details, see Documentation/locking/lockdep-design.txt.
+
 config DEBUG_RT_MUTEXES
 	bool "RT Mutex debugging, deadlock detection"
 	depends on DEBUG_KERNEL && RT_MUTEXES
@@ -1175,6 +1182,10 @@ config DEBUG_LOCK_ALLOC
 	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
 	 held during task exit.
 
+	 This feature enables LOCKDEP which can harm system performance
+	 even x3 times.
+	 For more details, see Documentation/locking/lockdep-design.txt.
+
 config LOCKDEP
 	bool
 	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
-- 
2.7.4