From d9c142bb8924559c277335822d2d64d0c1b3fc0b Mon Sep 17 00:00:00 2001 From: Chris Redpath Date: Wed, 30 May 2018 13:16:41 +0100 Subject: FROMLIST: sched/fair: Don't move tasks to lower capacity cpus unless necessary When lower capacity CPUs are load balancing and considering to pull something from a higher capacity group, we should not pull tasks from a cpu with only one task running as this is guaranteed to impede progress for that task. If there is more than one task running, load balance in the higher capacity group would have already made any possible moves to resolve imbalance and we should make better use of system compute capacity by moving a task if we still have more than one running. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Chris Redpath Signed-off-by: Morten Rasmussen [from https://lore.kernel.org/lkml/1530699470-29808-11-git-send-email-morten.rasmussen@arm.com/] Signed-off-by: Chris Redpath Change-Id: Ib86570abdd453a51be885b086c8d80be2773a6f2 Signed-off-by: Adam W. Willis --- kernel/sched/fair.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ca08e59c36a8..31d0cfa0ea6b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10407,6 +10407,17 @@ static struct rq *find_busiest_queue(struct lb_env *env, capacity = capacity_of(i); + /* + * For ASYM_CPUCAPACITY domains, don't pick a cpu that could + * eventually lead to active_balancing high->low capacity. + * Higher per-cpu capacity is considered better than balancing + * average load. + */ + if (env->sd->flags & SD_ASYM_CPUCAPACITY && + capacity_of(env->dst_cpu) < capacity && + rq->nr_running == 1) + continue; + wl = weighted_cpuload(i); /* -- cgit v1.2.3