From: Yicong Yang <yangyicong@huawei.com>
To: Abel Wu <wuyun.abel@bytedance.com>,
Peter Zijlstra <peterz@infradead.org>,
Mel Gorman <mgorman@suse.de>,
Vincent Guittot <vincent.guittot@linaro.org>
Cc: <yangyicong@hisilicon.com>, Josh Don <joshdon@google.com>,
Chen Yu <yu.c.chen@intel.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/5] sched/fair: ignore SIS_UTIL when has idle core
Date: Thu, 14 Jul 2022 14:19:39 +0800 [thread overview]
Message-ID: <8e7d75d4-613e-f35e-e932-323789666fb1@huawei.com> (raw)
In-Reply-To: <20220712082036.5130-2-wuyun.abel@bytedance.com>
On 2022/7/12 16:20, Abel Wu wrote:
> When SIS_UTIL is enabled, SIS domain scan will be skipped if
> the LLC is overloaded. Since the overloaded status is checked
> in the load balancing at LLC level, the interval is llc_size
> miliseconds. The duration might be long enough to affect the
> overall system throughput if idle cores are out of reach in
> SIS domain scan.
>
> Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
> ---
> kernel/sched/fair.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index a78d2e3b9d49..cd758b3616bd 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6392,16 +6392,19 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool
> struct sched_domain *this_sd;
> u64 time = 0;
>
> - this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
> - if (!this_sd)
> - return -1;
> -
> cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
>
> - if (sched_feat(SIS_PROP) && !has_idle_core) {
> + if (has_idle_core)
> + goto scan;
> +
> + if (sched_feat(SIS_PROP)) {
> u64 avg_cost, avg_idle, span_avg;
> unsigned long now = jiffies;
>
> + this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
> + if (!this_sd)
> + return -1;
> +
I don't follow the change here. True that this_sd is used only in SIS_PROP, but it seems irrelevant with your
commit. Does the position of this make any performance difference?
Thanks.
> /*
> * If we're busy, the assumption that the last idle period
> * predicts the future is flawed; age away the remaining
> @@ -6436,7 +6439,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool
> return -1;
> }
> }
> -
> +scan:
> for_each_cpu_wrap(cpu, cpus, target + 1) {
> if (has_idle_core) {
> i = select_idle_core(p, cpu, cpus, &idle_cpu);
>
next prev parent reply other threads:[~2022-07-14 6:19 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-12 8:20 [PATCH 0/5] sched/fair: SIS improvements and cleanups Abel Wu
2022-07-12 8:20 ` [PATCH 1/5] sched/fair: ignore SIS_UTIL when has idle core Abel Wu
2022-07-13 3:47 ` Chen Yu
2022-07-13 16:14 ` Abel Wu
2022-07-14 6:19 ` Yicong Yang [this message]
2022-07-14 6:58 ` Abel Wu
2022-07-14 7:15 ` Yicong Yang
2022-07-14 8:00 ` Abel Wu
2022-07-14 8:16 ` Yicong Yang
2022-07-14 8:34 ` Yicong Yang
2022-08-04 9:59 ` Chen Yu
2022-08-15 2:54 ` Abel Wu
2022-08-10 13:50 ` Chen Yu
2022-08-15 2:44 ` Abel Wu
2022-08-29 13:08 ` Mel Gorman
2022-08-29 14:11 ` Abel Wu
2022-08-29 14:56 ` Mel Gorman
2022-09-01 13:08 ` Abel Wu
2022-09-02 4:12 ` Abel Wu
2022-09-02 10:25 ` Mel Gorman
2022-09-05 14:40 ` Abel Wu
2022-09-06 9:57 ` Mel Gorman
2022-09-07 7:27 ` Chen Yu
2022-09-07 8:41 ` Mel Gorman
2022-09-07 7:52 ` Abel Wu
2022-07-12 8:20 ` [PATCH 2/5] sched/fair: default to false in test_idle_cores Abel Wu
2022-08-29 12:36 ` Mel Gorman
2022-07-12 8:20 ` [PATCH 3/5] sched/fair: remove redundant check in select_idle_smt Abel Wu
2022-08-29 12:36 ` Mel Gorman
2022-07-12 8:20 ` [PATCH 4/5] sched/fair: avoid double search on same cpu Abel Wu
2022-08-29 12:36 ` Mel Gorman
2022-07-12 8:20 ` [PATCH 5/5] sched/fair: remove useless check in select_idle_core Abel Wu
2022-08-29 12:37 ` Mel Gorman
2022-08-15 13:31 ` [PATCH 0/5] sched/fair: SIS improvements and cleanups Abel Wu
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