Re: [patch v4 07/18] sched: set initial load avg of new forked task

From: Alex Shi
Date: Thu Feb 14 2013 - 08:08:32 EST



> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 1dff78a..9d1c193 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1557,8 +1557,8 @@ static void __sched_fork(struct task_struct *p)
> * load-balance).
> */
> #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.runnable_avg_period = 1024;
> + p->se.avg.runnable_avg_sum = 1024;

It can't work.
avg.decay_count needs to be set to 0 before enqueue_entity_load_avg(), then
update_entity_load_avg() can't be called, so, runnable_avg_period/sum
are unusable.

Even we has chance to call __update_entity_runnable_avg(),
avg.last_runnable_update needs be set before that, usually, it needs to
be set as 'now', that cause __update_entity_runnable_avg() function
return 0, then update_entity_load_avg() still can not reach to
__update_entity_load_avg_contrib().

If we embed a simple new task load initialization to many functions,
that is too hard for future reader.

> #endif
> #ifdef CONFIG_SCHEDSTATS
> memset(&p->se.statistics, 0, sizeof(p->se.statistics));
>
>
>
>>
>>
>> --
>> Thanks
>> Alex


--
Thanks
Alex
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