Messages in this thread Patch in this message | | | From | Vincent Guittot <> | Subject | [PATCH 3/3] sched/fair: fix unnecessary increase of balance interval | Date | Tue, 7 Aug 2018 17:56:27 +0200 |
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In case of active balance, we increase the balance interval to cover pinned tasks cases not covered by all_pinned logic. Neverthless, the active migration triggered by asym packing should be treated as the normal unbalanced case and reset the interval to default value otherwise active migration for asym_packing can be easily delayed for hundreds of ms because of this all_pinned detection mecanism.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> --- kernel/sched/fair.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5f1b6c6..ceb6bed 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8360,22 +8360,32 @@ static struct rq *find_busiest_queue(struct lb_env *env, */ #define MAX_PINNED_INTERVAL 512 -static int need_active_balance(struct lb_env *env) +static inline bool +asym_active_balance(enum cpu_idle_type idle, unsigned int flags, int dst, int src) { - struct sched_domain *sd = env->sd; - - if (env->idle != CPU_NOT_IDLE) { + if (idle != CPU_NOT_IDLE) { /* * ASYM_PACKING needs to force migrate tasks from busy but * lower priority CPUs in order to pack all tasks in the * highest priority CPUs. */ - if ((sd->flags & SD_ASYM_PACKING) && - sched_asym_prefer(env->dst_cpu, env->src_cpu)) - return 1; + if ((flags & SD_ASYM_PACKING) && + sched_asym_prefer(dst, src)) + return true; } + return false; +} + +static int need_active_balance(struct lb_env *env) +{ + struct sched_domain *sd = env->sd; + + + if (asym_active_balance(env->idle, sd->flags, env->dst_cpu, env->src_cpu)) + return 1; + /* * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task. * It's worth migrating the task if the src_cpu's capacity is reduced @@ -8650,7 +8660,8 @@ static int load_balance(int this_cpu, struct rq *this_rq, } else sd->nr_balance_failed = 0; - if (likely(!active_balance)) { + if (likely(!active_balance) || + asym_active_balance(env.idle, sd->flags, env.dst_cpu, env.src_cpu)) { /* We were unbalanced, so reset the balancing interval */ sd->balance_interval = sd->min_interval; } else { -- 2.7.4
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