Re: [patch v7 15/21] sched: pull all tasks from source group

[Namhyung Kim <namhyung@kernel.org>]

Hi Alex,

On Thu,  4 Apr 2013 10:00:56 +0800, Alex Shi wrote:
> In power balance, we hope some sched groups are fully empty to save
> CPU power of them. So, we want to move any tasks from them.
>
> Signed-off-by: Alex Shi <alex.shi@intel.com>
> ---
>  kernel/sched/fair.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index f861427..0dd29f4 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5105,7 +5105,9 @@ static struct rq *find_busiest_queue(struct lb_env *env,
>  		 * When comparing with imbalance, use weighted_cpuload()
>  		 * which is not scaled with the cpu power.
>  		 */
> -		if (capacity && rq->nr_running == 1 && wl > env->imbalance)
> +		if (rq->nr_running == 0 ||
> +			(!(env->flags & LBF_POWER_BAL) && capacity &&
> +				rq->nr_running == 1 && wl > env->imbalance))

Just out of curious.

In load_balance(), we only move normal tasks, right?

Then shouldn't it check rq->cfs.h_nr_running rather than rq->nr_running?

Thanks,
Namhyung


>  			continue;
>  
>  		/*
> @@ -5208,7 +5210,8 @@ redo:
>  
>  	ld_moved = 0;
>  	lb_iterations = 1;
> -	if (busiest->nr_running > 1) {
> +	if (busiest->nr_running > 1 ||
> +		(busiest->nr_running == 1 && env.flags & LBF_POWER_BAL)) {
>  		/*
>  		 * Attempt to move tasks. If find_busiest_group has found
>  		 * an imbalance but busiest->nr_running <= 1, the group is