From cda2bd333be6e5e8c38fa072c9c4c296312dfd8d Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Mon, 26 Jan 2015 19:47:28 +0000 Subject: [PATCH] sched: Enable idle balance to pull single task towards cpu with higher capacity We do not want to miss out on the ability to pull a single remaining task from a potential source cpu towards an idle destination cpu. Add an extra criteria to need_active_balance() to kick off active load balance if the source cpu is over-utilized and has lower capacity than the destination cpu. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Morten Rasmussen Signed-off-by: Dietmar Eggemann --- kernel/sched/fair.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index bebc8367edee..fe40cdb8e640 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4779,6 +4779,11 @@ static inline bool task_fits_spare(struct task_struct *p, int cpu) return __task_fits(p, cpu, cpu_util(cpu)); } +static bool cpu_overutilized(int cpu) +{ + return (capacity_of(cpu) * 1024) < (cpu_util(cpu) * capacity_margin); +} + /* * find_idlest_group finds and returns the least busy CPU group within the * domain. @@ -6995,6 +7000,13 @@ static int need_active_balance(struct lb_env *env) return 1; } + if ((capacity_of(env->src_cpu) < capacity_of(env->dst_cpu)) && + env->src_rq->cfs.h_nr_running == 1 && + cpu_overutilized(env->src_cpu) && + !cpu_overutilized(env->dst_cpu)) { + return 1; + } + return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); } -- 2.20.1