sched/fair: fix use stale overloaded status to find busiest group
PATCH v2 1/1 sched/fair: fix use stale overloaded status to find busiest group
Commit caeb178c60f4 ("sched/fair: Make update_sd_pick_busiest() return 'true' on a busier sd") makes groups are ranked in the order overloaded > imbalance > other and busiest group is picked according to this order. sgs->group_capacity_factor is used to check if group is overloaded.
In the case of the child domain prefers tasks go to siblings first, the sgs->group_capacity_factor will be set lower to one in order to move all the excess tasks away.
However, group overloaded status is not updated in the case of sgs->group_capacity_factor be set lower to one which leads to miss find the busiest group.
This patch fix it by updating group overloaded status in the case of sg capacity factor is set to one in order to find busiest group accurately.
---
v1 -> v2:
* introduce some newlines in the changelog.
kernel/sched/fair.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
kernel/sched/fair.c +3 -1
@@ -6344,8 +6344,10 @@ 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;
Signature · 1 line
1.9.1
tip-bot for Wanpeng Li
merge bot[tip:sched/core] sched/fair: Fix stale overloaded status in the busiest group finding logic
sched/fair: Fix stale overloaded status in the busiest group finding logic
Commit-ID: cb0b9f2445cdf9893352e4548582a2892af7137c Gitweb: http://git.kernel.org/tip/cb0b9f2445cdf9893352e4548582a2892af7137c Author: Wanpeng Li <[email protected]> AuthorDate: Wed, 5 Nov 2014 07:44:50 +0800 Committer: Ingo Molnar <[email protected]> CommitDate: Sun, 16 Nov 2014 10:58:56 +0100
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.
--- kernel/sched/fair.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
kernel/sched/fair.c +3 -1
@@ -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;