Re: [PATCH] sched/rt: optimize checking group rt scheduler constraints

[Konstantin Khlebnikov]

On 25/01/2020 18.32, Cyrill Gorcunov wrote:
> On Sat, Jan 25, 2020 at 05:50:38PM +0300, Konstantin Khlebnikov wrote:
> ...
> > -/* Must be called with tasklist_lock held */
> >   static inline int tg_has_rt_tasks(struct task_group *tg)
> >   {
> > -	struct task_struct *g, *p;
> > +	struct task_struct *task;
> > +	struct css_task_iter it;
> > +	int ret = 0;
> >   
> >   	/*
> >   	 * Autogroups do not have RT tasks; see autogroup_create().
> > @@ -2407,12 +2408,12 @@ static inline int tg_has_rt_tasks(struct task_group *tg)
> >   	if (task_group_is_autogroup(tg))
> >   		return 0;
> >   
> > -	for_each_process_thread(g, p) {
> > -		if (rt_task(p) && task_group(p) == tg)
> > -			return 1;
> > -	}
> > +	css_task_iter_start(&tg->css, 0, &it);
> > +	while (!ret && (task = css_task_iter_next(&it)))
> > +		ret |= rt_task(task);
>
> Plain 'ret = rt_task(task);' won't work?

Should work too =)

> > +	css_task_iter_end(&it);
> >   
> > -	return 0;
> > +	return ret;
> >   }