From: Steven Rostedt <rostedt@goodmis.org>
To: "pang.xunlei" <pang.xunlei@linaro.org>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@gmail.com>
Subject: Re: [PATCH v2 4/4] sched/deadline: change cpudl_find() to return bool instead of best_cpu
Date: Wed, 19 Nov 2014 11:30:08 -0500 [thread overview]
Message-ID: <20141119113008.1db0b463@gandalf.local.home> (raw)
In-Reply-To: <1416411982-1204-4-git-send-email-pang.xunlei@linaro.org>
On Wed, 19 Nov 2014 23:46:22 +0800
"pang.xunlei" <pang.xunlei@linaro.org> wrote:
> cpudl_find() is not a good place to select the best cpu, so leave
> this role to its call site, currently it is find_later_rq() where
> we can do the election of the best cpu according to sd topology.
>
> Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
> ---
> kernel/sched/cpudeadline.c | 15 +++++----------
> kernel/sched/deadline.c | 17 ++++++-----------
> 2 files changed, 11 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
> index 3047846..41d3578 100644
> --- a/kernel/sched/cpudeadline.c
> +++ b/kernel/sched/cpudeadline.c
> @@ -100,29 +100,24 @@ static inline int cpudl_maximum(struct cpudl *cp)
> * @later_mask: a mask to fill in with the selected CPUs (not NULL)
> * @set_flag: indicate if later_mask should be set
> *
> - * Returns: int - best CPU (heap maximum if suitable)
> + * Return: (int)bool - CPUs were found
> */
> int cpudl_find(struct cpudl *cp, struct task_struct *p,
> struct cpumask *later_mask, int set_flag)
> {
> - int best_cpu = -1;
> const struct sched_dl_entity *dl_se = &p->dl;
>
> cpumask_and(later_mask, cpu_active_mask, &p->cpus_allowed);
> if (cpumask_and(later_mask, later_mask, cp->free_cpus)) {
> - best_cpu = cpumask_any(later_mask);
> - goto out;
> + return 1;
> } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
> dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
> - best_cpu = cpudl_maximum(cp);
> if (set_flag)
> - cpumask_set_cpu(best_cpu, later_mask);
> + cpumask_set_cpu(cpudl_maximum(cp), later_mask);
> + return 1;
> }
>
> -out:
> - WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
You lost this warning. It should be moved too.
> -
> - return best_cpu;
> + return 0;
> }
>
> /*
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index e8208d0..3e82cf3 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -976,7 +976,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
> * let's hope p can move out.
> */
> if (rq->curr->nr_cpus_allowed == 1 ||
> - cpudl_find(&rq->rd->cpudl, rq->curr, later_mask, 0) == -1)
> + !cpudl_find(&rq->rd->cpudl, rq->curr, later_mask, 0))
> return;
>
> /*
> @@ -984,7 +984,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p)
> * see if it is pushed or pulled somewhere else.
> */
> if (p->nr_cpus_allowed != 1 &&
> - cpudl_find(&rq->rd->cpudl, p, later_mask, 0) != -1)
> + cpudl_find(&rq->rd->cpudl, p, later_mask, 0))
> return;
>
> resched_curr(rq);
> @@ -1189,9 +1189,7 @@ static int find_later_rq(struct task_struct *task)
> * We have to consider system topology and task affinity
> * first, then we can look for a suitable cpu.
> */
> - best_cpu = cpudl_find(&task_rq(task)->rd->cpudl,
> - task, later_mask, 1);
> - if (best_cpu == -1)
> + if (!cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask, 1))
> return -1;
>
> /*
> @@ -1230,12 +1228,9 @@ static int find_later_rq(struct task_struct *task)
> return this_cpu;
> }
>
> - /*
> - * Last chance: if best_cpu is valid and is
> - * in the mask, that becomes our choice.
> - */
> - if (best_cpu < nr_cpu_ids &&
> - cpumask_test_cpu(best_cpu, sched_domain_span(sd))) {
> + best_cpu = cpumask_first_and(lowest_mask,
> + sched_domain_span(sd));
Sometimes that 80 character rule isn't the best for readability. But
that is Peter's or Juri's call.
> + if (best_cpu < nr_cpu_ids) {
The warning should probably go here.
-- Steve
> rcu_read_unlock();
> return best_cpu;
> }
next prev parent reply other threads:[~2014-11-19 16:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-19 15:46 [PATCH v2 1/4] sched/deadline: Modify cpudl.free_cpus to reflect rd->span pang.xunlei
2014-11-19 15:46 ` [PATCH v2 2/4] sched/deadline: Fix wrong cpudl_find() in check_preempt_equal_dl() pang.xunlei
2014-11-19 15:46 ` [PATCH v2 3/4] sched/deadline: add the "set_flag" argument to cpudl_find() pang.xunlei
2014-11-19 16:24 ` Steven Rostedt
2014-11-20 14:58 ` pang.xunlei
2014-11-20 15:06 ` pang.xunlei
2014-11-19 15:46 ` [PATCH v2 4/4] sched/deadline: change cpudl_find() to return bool instead of best_cpu pang.xunlei
2014-11-19 16:30 ` Steven Rostedt [this message]
2014-11-20 9:00 ` [PATCH v2 1/4] sched/deadline: Modify cpudl.free_cpus to reflect rd->span Wanpeng Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141119113008.1db0b463@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=juri.lelli@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=pang.xunlei@linaro.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).