From: Parth Shah <parth@linux.ibm.com>
To: subhra mazumdar <subhra.mazumdar@oracle.com>,
linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, mingo@redhat.com, tglx@linutronix.de,
steven.sistare@oracle.com, dhaval.giani@oracle.com,
daniel.lezcano@linaro.org, vincent.guittot@linaro.org,
viresh.kumar@linaro.org, tim.c.chen@linux.intel.com,
mgorman@techsingularity.net, patrick.bellasi@arm.com
Subject: Re: [RFC PATCH 9/9] sched: rotate the cpu search window for better spread
Date: Thu, 5 Sep 2019 12:07:47 +0530 [thread overview]
Message-ID: <0931a2e0-0fbf-be64-d6c0-cba7745bb152@linux.ibm.com> (raw)
In-Reply-To: <20190830174944.21741-10-subhra.mazumdar@oracle.com>
On 8/30/19 11:19 PM, subhra mazumdar wrote:
> Rotate the cpu search window for better spread of threads. This will ensure
> an idle cpu will quickly be found if one exists.
>
> Signed-off-by: subhra mazumdar <subhra.mazumdar@oracle.com>
> ---
> kernel/sched/fair.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 94dd4a32..7419b47 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6188,7 +6188,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> u64 avg_cost, avg_idle;
> u64 time, cost;
> s64 delta;
> - int cpu, floor, nr = INT_MAX;
> + int cpu, floor, target_tmp, nr = INT_MAX;
>
> this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
> if (!this_sd)
> @@ -6213,9 +6213,15 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> nr = floor;
> }
>
> + if (per_cpu(next_cpu, target) != -1)
> + target_tmp = per_cpu(next_cpu, target);
> + else
> + target_tmp = target;
> +
> time = local_clock();
>
> - for_each_cpu_wrap(cpu, sched_domain_span(sd), target) {
> + for_each_cpu_wrap(cpu, sched_domain_span(sd), target_tmp) {
> + per_cpu(next_cpu, target) = cpu;
Is it possible that two simultaneous select_idle_cpu call have the same target value?
> if (!--nr)
> return -1;
> if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
>
next prev parent reply other threads:[~2019-09-05 6:38 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 17:49 [RFC PATCH 0/9] Task latency-nice subhra mazumdar
2019-08-30 17:49 ` [RFC PATCH 1/9] sched,cgroup: Add interface for latency-nice subhra mazumdar
2019-09-04 17:32 ` Tim Chen
2019-09-05 6:15 ` Parth Shah
2019-09-05 10:11 ` Patrick Bellasi
2019-09-06 12:22 ` Parth Shah
2019-09-05 8:31 ` Peter Zijlstra
2019-09-05 9:45 ` Patrick Bellasi
2019-09-05 10:46 ` Peter Zijlstra
2019-09-05 11:13 ` Qais Yousef
2019-09-05 11:30 ` Peter Zijlstra
2019-09-05 11:40 ` Patrick Bellasi
2019-09-05 11:48 ` Peter Zijlstra
2019-09-05 13:32 ` Qais Yousef
2019-09-05 11:47 ` Qais Yousef
2020-04-16 0:02 ` Joel Fernandes
2020-04-16 17:23 ` Dietmar Eggemann
2020-04-18 16:01 ` Joel Fernandes
2020-04-20 11:26 ` Parth Shah
2020-04-20 19:14 ` Joel Fernandes
2020-04-20 11:47 ` Qais Yousef
2020-04-20 19:10 ` Joel Fernandes
2019-09-05 11:30 ` Patrick Bellasi
2019-09-05 11:47 ` Peter Zijlstra
2019-09-05 11:18 ` Patrick Bellasi
2019-09-05 11:40 ` Peter Zijlstra
2019-09-05 11:46 ` Patrick Bellasi
2019-09-05 11:46 ` Valentin Schneider
2019-09-05 13:07 ` Patrick Bellasi
2019-09-05 14:48 ` Valentin Schneider
2019-09-06 12:45 ` Parth Shah
2019-09-06 14:13 ` Valentin Schneider
2019-09-06 14:32 ` Vincent Guittot
2019-09-06 17:10 ` Parth Shah
2019-09-06 22:50 ` Valentin Schneider
2019-09-06 12:31 ` Parth Shah
2019-09-05 10:05 ` Patrick Bellasi
2019-09-05 10:48 ` Peter Zijlstra
2019-08-30 17:49 ` [RFC PATCH 2/9] sched: add search limit as per latency-nice subhra mazumdar
2019-09-05 6:22 ` Parth Shah
2019-08-30 17:49 ` [RFC PATCH 3/9] sched: add sched feature to disable idle core search subhra mazumdar
2019-09-05 10:17 ` Patrick Bellasi
2019-09-05 22:02 ` Subhra Mazumdar
2019-08-30 17:49 ` [RFC PATCH 4/9] sched: SIS_CORE " subhra mazumdar
2019-09-05 10:19 ` Patrick Bellasi
2019-08-30 17:49 ` [RFC PATCH 5/9] sched: Define macro for number of CPUs in core subhra mazumdar
2019-08-30 17:49 ` [RFC PATCH 6/9] x86/smpboot: Optimize cpumask_weight_sibling macro for x86 subhra mazumdar
2019-08-30 17:49 ` [RFC PATCH 7/9] sched: search SMT before LLC domain subhra mazumdar
2019-09-05 9:31 ` Peter Zijlstra
2019-09-05 20:40 ` Subhra Mazumdar
2019-08-30 17:49 ` [RFC PATCH 8/9] sched: introduce per-cpu var next_cpu to track search limit subhra mazumdar
2019-08-30 17:49 ` [RFC PATCH 9/9] sched: rotate the cpu search window for better spread subhra mazumdar
2019-09-05 6:37 ` Parth Shah [this message]
2019-09-05 5:55 ` [RFC PATCH 0/9] Task latency-nice Parth Shah
2019-09-05 10:31 ` Patrick Bellasi
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