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Subject[PATCH] Inline double_unlock_balance()

We have a test case which measures the variation in the amount of time
needed to perform a fixed amount of work on the preempt_rt kernel. We
started seeing deterioration in it's performance recently. The test
should never take more than 10 microseconds, but we started 5-10%
failure rate. Using elimination method, we traced the problem to commit
1b12bbc747560ea68bcc132c3d05699e52271da0 (lockdep: re-annotate
scheduler runqueues). When LOCKDEP is disabled, this patch only adds an
additional function call to double_unlock_balance(). Hence I inlined
double_unlock_balance() and the problem went away. Here is a patch to
make this change.


lockdep: Inline double_unlock_balance()

Additional function call for double_unlock_balance() causes latency
problems for some test cases on the preempt_rt kernel.

Signed-off-by: Sripathi Kodi <>

Index: linux-
--- linux- 2008-11-05 05:01:01.000000000 -0800
+++ linux- 2008-11-05 05:01:20.000000000 -0800
@@ -2812,7 +2812,7 @@
return ret;

-static void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
+static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)

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