sched: Try to deal with low capacity, fix update_sd_power_savings_stats()

sgs.group_capacity can now be 0, if for some reason
group->__cpu_power happens to be less than SCHED_LOAD_SCALE/2.

In that case, we need the following fix to make it work for
update_sd_power_savings_stats(). That's because both
sum_nr_running and group_capacity are unsigned longs.

Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched.c b/kernel/sched.c
index 5f5b359..e1ebf9b 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3668,7 +3668,7 @@ static inline void update_sd_power_savings_stats(struct sched_group *group,
         * capacity but still has some space to pick up some load
         * from other group and save more power
         */
-       if (sgs->sum_nr_running > sgs->group_capacity - 1)
+       if (sgs->sum_nr_running + 1 > sgs->group_capacity)
                return;
 
        if (sgs->sum_nr_running > sds->leader_nr_running ||