Re: [PATCH v2 1/3] sched: don't repeat the initialization insched_init()

From: Peter Zijlstra
Date: Wed Jun 05 2013 - 07:07:20 EST


On Wed, Jun 05, 2013 at 10:24:18AM +0800, Michael Wang wrote:
> v2:
> Move comments back before init_tg_cfs_entry(). (Thanks for the notify from pjt)
>
> In sched_init(), there is no need to initialize 'root_task_group.shares' and
> 'root_task_group.cfs_bandwidth' repeatedly.
>
> CC: Paul Tuner <pjt@xxxxxxxxxx>
> CC: Ingo Molnar <mingo@xxxxxxxxxx>
> CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Michael Wang <wangyun@xxxxxxxxxxxxxxxxxx>
> ---
> kernel/sched/core.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 58453b8..96f69da 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6955,6 +6955,11 @@ void __init sched_init(void)
>
> #endif /* CONFIG_CGROUP_SCHED */
>
> +#ifdef CONFIG_FAIR_GROUP_SCHED
> + root_task_group.shares = ROOT_TASK_GROUP_LOAD;
> + init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
> +#endif
> +
> for_each_possible_cpu(i) {
> struct rq *rq;
>
> @@ -6966,7 +6971,6 @@ void __init sched_init(void)
> init_cfs_rq(&rq->cfs);
> init_rt_rq(&rq->rt, rq);
> #ifdef CONFIG_FAIR_GROUP_SCHED
> - root_task_group.shares = ROOT_TASK_GROUP_LOAD;
> INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
> /*
> * How much cpu bandwidth does root_task_group get?
> @@ -6987,7 +6991,6 @@ void __init sched_init(void)
> * We achieve this by letting root_task_group's tasks sit
> * directly in rq->cfs (i.e root_task_group->se[] = NULL).
> */
> - init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
> init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
> #endif /* CONFIG_FAIR_GROUP_SCHED */

I would actually like a patch reducing the #ifdef forest there, not
adding to it.

There's no actual harm in doing the initialization mutliple times,
right?
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