On Mon, Jun 3, 2013 at 11:23 PM, Michael Wang
<[email protected]> wrote:
> In sched_init(), there is no need to initialize 'root_task_group.shares' and
> 'root_task_group.cfs_bandwidth' repeatedly.
>
> CC: Ingo Molnar <[email protected]>
> CC: Peter Zijlstra <[email protected]>
> Signed-off-by: Michael Wang <[email protected]>
> ---
> kernel/sched/core.c | 46 +++++++++++++++++++++++++---------------------
> 1 files changed, 25 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 58453b8..c0c3716 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6955,6 +6955,31 @@ void __init sched_init(void)
>
> #endif /* CONFIG_CGROUP_SCHED */
>
> +#ifdef CONFIG_FAIR_GROUP_SCHED
> + root_task_group.shares = ROOT_TASK_GROUP_LOAD;
> +
> + /*
> + * How much cpu bandwidth does root_task_group get?
> + *
> + * In case of task-groups formed thr' the cgroup filesystem, it
> + * gets 100% of the cpu resources in the system. This overall
> + * system cpu resource is divided among the tasks of
> + * root_task_group and its child task-groups in a fair manner,
> + * based on each entity's (task or task-group's) weight
> + * (se->load.weight).
> + *
> + * In other words, if root_task_group has 10 tasks of weight
> + * 1024) and two child groups A0 and A1 (of weight 1024 each),
> + * then A0's share of the cpu resource is:
> + *
> + * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
> + *
> + * We achieve this by letting root_task_group's tasks sit
> + * directly in rq->cfs (i.e root_task_group->se[] = NULL).
> + */
This comment has become unglued from what it's supposed to be attached
to (it's tied to root_task_group.shares & init_tg_cfs_entry, not
init_cfs_bandwidth).
> + init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
> +#endif
> +
> for_each_possible_cpu(i) {
> struct rq *rq;
>
> @@ -6966,28 +6991,7 @@ 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?
> - *
> - * In case of task-groups formed thr' the cgroup filesystem,
> it
> - * gets 100% of the cpu resources in the system. This overall
> - * system cpu resource is divided among the tasks of
> - * root_task_group and its child task-groups in a fair manner,
> - * based on each entity's (task or task-group's) weight
> - * (se->load.weight).
> - *
> - * In other words, if root_task_group has 10 tasks of weight
> - * 1024) and two child groups A0 and A1 (of weight 1024 each),
> - * then A0's share of the cpu resource is:
> - *
> - * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) =
> 8.33%
> - *
> - * 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 */
>
> --
> 1.7.4.1
>
> --
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