rcu: Default jiffies_to_sched_qs to jiffies_till_sched_qs

The current code only calls adjust_jiffies_till_sched_qs() if
jiffies_till_sched_qs is left at its default value, so when the
jiffies_till_sched_qs kernel-boot parameter actually is specified,
jiffies_to_sched_qs will be left with the value zero, which
will result in useless slowdowns of cond_resched().  This commit
therefore changes rcu_init_geometry() to unconditionally invoke
adjust_jiffies_till_sched_qs(), which ensures that jiffies_to_sched_qs
will be initialized in all cases, thus maintaining good cond_resched()
performance.

Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 139fa1f5c5378e22933f50d7c1406f05926ce2d9..466299c3d2da6ade267cb5603cc8cd138848dbbf 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3739,8 +3739,7 @@ static void __init rcu_init_geometry(void)
                jiffies_till_first_fqs = d;
        if (jiffies_till_next_fqs == ULONG_MAX)
                jiffies_till_next_fqs = d;
-       if (jiffies_till_sched_qs == ULONG_MAX)
-               adjust_jiffies_till_sched_qs();
+       adjust_jiffies_till_sched_qs();
 
        /* If the compile-time values are accurate, just leave. */
        if (rcu_fanout_leaf == RCU_FANOUT_LEAF &&