From cb0b9f2445cdf9893352e4548582a2892af7137c Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Wed, 5 Nov 2014 07:44:50 +0800 Subject: [PATCH] sched/fair: Fix stale overloaded status in the busiest group finding logic Commit caeb178c60f4 ("sched/fair: Make update_sd_pick_busiest() return 'true' on a busier sd") changes groups to be ranked in the order of overloaded > imbalance > other, and busiest group is picked according to this order. sgs->group_capacity_factor is used to check if the group is overloaded. When the child domain prefers tasks to go to siblings first, the sgs->group_capacity_factor will be set lower than one in order to move all the excess tasks away. However, group overloaded status is not updated when sgs->group_capacity_factor is set to lower than one, which leads to us missing to find the busiest group. This patch fixes it by updating group overloaded status when sg capacity factor is set to one, in order to find the busiest group accurately. Signed-off-by: Wanpeng Li Signed-off-by: Peter Zijlstra (Intel) Cc: Rik van Riel Cc: Vincent Guittot Cc: Kirill Tkhai Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1415144690-25196-1-git-send-email-wanpeng.li@linux.intel.com [ Fixed the changelog. ] Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8bca292f0803..df2cdf77f899 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6352,8 +6352,10 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd * with a large weight task outweighs the tasks on the system). */ if (prefer_sibling && sds->local && - sds->local_stat.group_has_free_capacity) + sds->local_stat.group_has_free_capacity) { sgs->group_capacity_factor = min(sgs->group_capacity_factor, 1U); + sgs->group_type = group_classify(sg, sgs); + } if (update_sd_pick_busiest(env, sds, sg, sgs)) { sds->busiest = sg;