* Qi Zheng <arch0.zh...@gmail.com> wrote:
> 1. The group_has_capacity() function is only called in
> group_classify().
> 2. Before calling the group_has_capacity() function,
> group_is_overloaded() will first judge the following
> formula, if it holds, the group_classify() will directly
> return the group_overloaded.
>
> (sgs->group_capacity * imbalance_pct) <
> (sgs->group_runnable * 100)
>
> Therefore, when the group_has_capacity() is called, the
> probability that the above formalu holds is very small. Hint
> compilers about that.
>
> Signed-off-by: Qi Zheng <arch0.zh...@gmail.com>
> ---
> kernel/sched/fair.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 2ba8f230feb9..9074fd5e23b2 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8234,8 +8234,8 @@ group_has_capacity(unsigned int imbalance_pct, struct
> sg_lb_stats *sgs)
> if (sgs->sum_nr_running < sgs->group_weight)
> return true;
>
> - if ((sgs->group_capacity * imbalance_pct) <
> - (sgs->group_runnable * 100))
> + if (unlikely((sgs->group_capacity * imbalance_pct) <
> + (sgs->group_runnable * 100)))
> return false;
Isn't the probability that this second check will match around 0%?
I.e. wouldn't the right fix be to remove the duplicate check from
group_has_capacity(), because it's already been checked in
group_classify()? Maybe while leaving a comment in place?
Thanks,
Ingo
