Hi Vincent,
On 14/12/2018 16:01, Vincent Guittot wrote:
> newly idle load balance is not always triggered when a cpu becomes idle.
> This prevent the scheduler to get a chance to migrate task for asym packing.
> Enable active migration because of asym packing during idle load balance too.
>
> Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
> ---
> kernel/sched/fair.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index c215f7a..9591e7a 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8861,7 +8861,7 @@ static int need_active_balance(struct lb_env *env)
> {
> struct sched_domain *sd = env->sd;
>
> - if (env->idle == CPU_NEWLY_IDLE) {
> + if (env->idle != CPU_NOT_IDLE) {
>
> /*
> * ASYM_PACKING needs to force migrate tasks from busy but
>
That change looks fine. However, you're mentioning newidle load_balance()
not being triggered - you'd want to set root_domain->overload for any
newidle pull to happen, probably with something like this:
-----8<-----
@@ -8398,6 +8408,9 @@ static inline void update_sd_lb_stats(struct lb_env *env,
struct sd_lb_stats *sd
sg = sg->next;
} while (sg != env->sd->groups);
+ if (check_asym_packing(env, sds))
+ sg_status |= SG_OVERLOAD;
+
#ifdef CONFIG_NO_HZ_COMMON
if ((env->flags & LBF_NOHZ_AGAIN) &&
cpumask_subset(nohz.idle_cpus_mask, sched_domain_span(env->sd))) {
----->8-----
It's similar to what is done for misfit, although that's yet another
'twisted' use of that flag which we might want to rename (I suggested
something like 'need_idle_balance' a while back but it wasn't really
popular).
