The following commit has been merged into the sched/core branch of tip: Commit-ID: 5e23e474431529b7d1480f649ce33d0e9c1b2e48 Gitweb: https://git.kernel.org/tip/5e23e474431529b7d1480f649ce33d0e9c1b2e48 Author: Vincent Guittot <vincent.guit...@linaro.org> AuthorDate: Fri, 18 Oct 2019 15:26:32 +02:00 Committer: Ingo Molnar <mi...@kernel.org> CommitterDate: Mon, 21 Oct 2019 09:40:54 +02:00
sched/fair: Use rq->nr_running when balancing load CFS load_balance() only takes care of CFS tasks whereas CPUs can be used by other scheduling classes. Typically, a CFS task preempted by an RT or deadline task will not get a chance to be pulled by another CPU because load_balance() doesn't take into account tasks from other classes. Add sum of nr_running in the statistics and use it to detect such situations. Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org> Cc: Ben Segall <bseg...@google.com> Cc: Dietmar Eggemann <dietmar.eggem...@arm.com> Cc: Juri Lelli <juri.le...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mel Gorman <mgor...@suse.de> Cc: Mike Galbraith <efa...@gmx.de> Cc: morten.rasmus...@arm.com Cc: Peter Zijlstra <pet...@infradead.org> Cc: Steven Rostedt <rost...@goodmis.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: hdan...@sina.com Cc: pa...@linux.ibm.com Cc: pa...@redhat.com Cc: quentin.per...@arm.com Cc: r...@surriel.com Cc: sri...@linux.vnet.ibm.com Cc: valentin.schnei...@arm.com Link: https://lkml.kernel.org/r/1571405198-27570-6-git-send-email-vincent.guit...@linaro.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/fair.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 76a2aa8..4e7396c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7694,6 +7694,7 @@ struct sg_lb_stats { unsigned long group_load; /* Total load over the CPUs of the group */ unsigned long group_capacity; unsigned long group_util; /* Total utilization of the group */ + unsigned int sum_nr_running; /* Nr of tasks running in the group */ unsigned int sum_h_nr_running; /* Nr of CFS tasks running in the group */ unsigned int idle_cpus; unsigned int group_weight; @@ -7928,7 +7929,7 @@ static inline int sg_imbalanced(struct sched_group *group) static inline bool group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) { - if (sgs->sum_h_nr_running < sgs->group_weight) + if (sgs->sum_nr_running < sgs->group_weight) return true; if ((sgs->group_capacity * 100) > @@ -7949,7 +7950,7 @@ group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) static inline bool group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) { - if (sgs->sum_h_nr_running <= sgs->group_weight) + if (sgs->sum_nr_running <= sgs->group_weight) return false; if ((sgs->group_capacity * 100) < @@ -8053,6 +8054,8 @@ static inline void update_sg_lb_stats(struct lb_env *env, sgs->sum_h_nr_running += rq->cfs.h_nr_running; nr_running = rq->nr_running; + sgs->sum_nr_running += nr_running; + if (nr_running > 1) *sg_status |= SG_OVERLOAD; @@ -8410,13 +8413,13 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s } if (busiest->group_weight == 1 || sds->prefer_sibling) { - unsigned int nr_diff = busiest->sum_h_nr_running; + unsigned int nr_diff = busiest->sum_nr_running; /* * When prefer sibling, evenly spread running tasks on * groups. */ env->migration_type = migrate_task; - lsub_positive(&nr_diff, local->sum_h_nr_running); + lsub_positive(&nr_diff, local->sum_nr_running); env->imbalance = nr_diff >> 1; return; } @@ -8580,7 +8583,7 @@ static struct sched_group *find_busiest_group(struct lb_env *env) /* Try to move all excess tasks to child's sibling domain */ if (sds.prefer_sibling && local->group_type == group_has_spare && - busiest->sum_h_nr_running > local->sum_h_nr_running + 1) + busiest->sum_nr_running > local->sum_nr_running + 1) goto force_balance; if (busiest->group_type != group_overloaded &&
