Re: [patch v5 01/15] sched: set initial value for runnable avg of sched entities.

Joonsoo Kim
2013-02-18T08:28:36Z

Hello, Alex.

On Mon, Feb 18, 2013 at 01:07:28PM +0800, Alex Shi wrote:
> We need initialize the se.avg.{decay_count, load_avg_contrib} to zero
> after a new task forked.
> Otherwise random values of above variables cause mess when do new task

I think that these are not random values. In arch_dup_task_struct(),
we do '*dst = *src', so, these values come from parent process. If we use
these value appropriately, we can anticipate child process' load easily.
So to initialize the load_avg_contrib to zero is not good idea for me.

Thanks.

> enqueue:
> enqueue_task_fair
> enqueue_entity
> enqueue_entity_load_avg
>
> Signed-off-by: Alex Shi <alex.shi@intel.com>
> ---
> kernel/sched/core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 26058d0..1743746 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1559,6 +1559,8 @@ static void __sched_fork(struct task_struct *p)
> #if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
> p->se.avg.runnable_avg_period = 0;
> p->se.avg.runnable_avg_sum = 0;
> + p->se.avg.decay_count = 0;
> + p->se.avg.load_avg_contrib = 0;
> #endif
> #ifdef CONFIG_SCHEDSTATS
> memset(&p->se.statistics, 0, sizeof(p->se.statistics));
> --
> 1.7.12
>
> --
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