On Wed, Apr 14, 2021 at 10:22:29AM +0800, qianjun.ker...@gmail.com wrote:
> From: jun qian <qianjun.ker...@gmail.com>
>
> As you are already set the TIF_NEED_RESCHED, there is no need
> to check resched again.
Still no justification; does this actually help anything?
> Signed-off-by: jun qian <qianjun.ker...@gmail.com>
> ---
> kernel/sched/fair.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 794c2cb945f8..1a69b5fffe4a 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4360,19 +4360,26 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct
> sched_entity *curr)
> {
> unsigned long ideal_runtime, delta_exec;
> struct sched_entity *se;
> + struct rq *rq = rq_of(cfs_rq);
> s64 delta;
>
> ideal_runtime = sched_slice(cfs_rq, curr);
> delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
> if (delta_exec > ideal_runtime) {
> - resched_curr(rq_of(cfs_rq));
> + if (!test_tsk_need_resched(rq->curr))
> + resched_curr(rq_of(cfs_rq));
> /*
> * The current task ran long enough, ensure it doesn't get
> * re-elected due to buddy favours.
> */
> clear_buddies(cfs_rq, curr);
> return;
> - }
> + /*
> + * If here with TIF_NEED_RESCHED already set from the early entity_tick,
> + * there is no need to check again.
> + */
> + } else if (test_tsk_need_resched(rq->curr))
> + return;
This is horrific style. And, afaict, completely unnecessary.
