On Wed, Feb 2, 2011 at 12:47 PM, Kirill A. Shutsemov
<kirill@xxxxxxxxxxxxx> wrote:
> From: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
>
> Provides a way of tasks grouping by timer slack value. Introduces per
> cgroup max and min timer slack value. When a task attaches to a cgroup,
> its timer slack value adjusts (if needed) to fit min-max range.
>
> It also provides a way to set timer slack value for all tasks in the
> cgroup at once.
>
> This functionality is useful in mobile devices where certain background
> apps are attached to a cgroup and minimum wakeups are desired.
If you really want to be able to make this modular, I'd be inclined to
make the check_timer_slack hook just default to NULL, rather than
introducing dummy_timer_slack_check()
> +
> +static int tslack_write_range(struct cgroup *cgroup, struct cftype *cft,
> + u64 val)
> +{
> + struct timer_slack_cgroup *tslack_cgroup;
> + struct cgroup_iter it;
> + struct task_struct *task;
> +
> + if (!val)
> + return -EINVAL;
> +
> + tslack_cgroup = cgroup_to_tslack_cgroup(cgroup);
> + switch (cft->private) {
> + case TIMER_SLACK_MIN:
> + if (val > tslack_cgroup->max_slack_ns)
> + return -EINVAL;
> + tslack_cgroup->min_slack_ns = val;
> + break;
> + case TIMER_SLACK_MAX:
> + if (val < tslack_cgroup->min_slack_ns)
> + return -EINVAL;
> + tslack_cgroup->max_slack_ns = val;
> + break;
> + default:
> + BUG();
> + }
> +
Don't we want to keep the min/max applied hierarchically as well? i.e.
a child can't set its min/max outside the range of its parents?
> +
> +static int __init init_cgroup_timer_slack(void)
> +{
> + BUG_ON(timer_slack_check != dummy_timer_slack_check);
Better to make this just fail the initialization if someone else has
already claimed the hook, rather than crashing.
Paul
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