Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit cf7f8690 authored by Sripathi Kodi's avatar Sripathi Kodi Committed by Ingo Molnar
Browse files

sched, lockdep: 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
1b12bbc7 (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.

Signed-off-by: default avatarSripathi Kodi <sripathik@in.ibm.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e113a745

kernel/sched.c

+1 −1
Original line number Diff line number Diff line
@@ -2825,7 +2825,7 @@ static int double_lock_balance(struct rq *this_rq, struct rq *busiest) 
	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)

	__releases(busiest->lock)

{

	spin_unlock(&busiest->lock);

kernel/sched_rt.c

+2 −1
Original line number Diff line number Diff line
@@ -910,7 +910,8 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p) 
#define RT_MAX_TRIES 3



static int double_lock_balance(struct rq *this_rq, struct rq *busiest);

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);



static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep);