From: Steven Rostedt <rostedt@goodmis.org>
To: Hui Su <sh_def@163.com>
Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/rt.c: use list_is_singular() instead of '->prev != ->next'
Date: Mon, 26 Oct 2020 14:29:56 -0400 [thread overview]
Message-ID: <20201026142956.0a429137@gandalf.local.home> (raw)
In-Reply-To: <20201026174152.GA10163@rlk>
On Tue, 27 Oct 2020 01:41:52 +0800
Hui Su <sh_def@163.com> wrote:
> Use the list_is_singular(&rt_se->run_list) api instead of
> 'rt_se->run_list.prev != rt_se->run_list.next'.
> Fix a comment by the way, and make the comment more clearly.
>
> Signed-off-by: Hui Su <sh_def@163.com>
> ---
> kernel/sched/rt.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 49ec096a8aa1..1479d00656b4 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -2381,7 +2381,7 @@ static inline void watchdog(struct rq *rq, struct task_struct *p) { }
> *
> * NOTE: This function can be called remotely by the tick offload that
> * goes along full dynticks. Therefore no local assumption can be made
> - * and everything must be accessed through the @rq and @curr passed in
> + * and everything must be accessed through the @rq and @p passed in
> * parameters.
> */
> static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
> @@ -2406,11 +2406,11 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
> p->rt.time_slice = sched_rr_timeslice;
>
> /*
> - * Requeue to the end of queue if we (and all of our ancestors) are not
> - * the only element on the queue
> + * Requeue to the end of rt_prio_array queue if we (and all of our
> + * ancestors) are not the only element on the rt_prio_array queue.
> */
> for_each_sched_rt_entity(rt_se) {
> - if (rt_se->run_list.prev != rt_se->run_list.next) {
> + if (!list_is_singular(&rt_se->run_list)) {
Perhaps there should be a list_has_more_than_one() API, as list_is_singular
requires two checks, and the "more_than_one" only requires a single check.
list_is_singular() is:
return !list_empty(list) && (list->next == list->prev);
which is more work than what you are replacing.
-- Steve
> requeue_task_rt(rq, p, 0);
> resched_curr(rq);
> return;
next prev parent reply other threads:[~2020-10-26 18:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 17:41 [PATCH] sched/rt.c: use list_is_singular() instead of '->prev != ->next' Hui Su
2020-10-26 18:29 ` Steven Rostedt [this message]
2020-10-27 2:07 ` 苏辉
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