From: Vincent Guittot <vincent.guittot@linaro.org>
To: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Yuyang Du <yuyang.du@intel.com>,
mgalbraith@suse.de, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 07/13] sched/fair: Let asymmetric cpu configurations balance at wake-up
Date: Wed, 13 Jul 2016 14:56:41 +0200 [thread overview]
Message-ID: <CAKfTPtDv-6eQQQTbB3aOCwRneabv0Gyq1Bi5SWAZUBT_BXNydw@mail.gmail.com> (raw)
In-Reply-To: <1466615004-3503-8-git-send-email-morten.rasmussen@arm.com>
On 22 June 2016 at 19:03, Morten Rasmussen <morten.rasmussen@arm.com> wrote:
> Currently, SD_WAKE_AFFINE always takes priority over wakeup balancing if
> SD_BALANCE_WAKE is set on the sched_domains. For asymmetric
> configurations SD_WAKE_AFFINE is only desirable if the waking task's
> compute demand (utilization) is suitable for all the cpu capacities
> available within the SD_WAKE_AFFINE sched_domain. If not, let wakeup
instead of "suitable for all the cpu capacities available within the
SD_WAKE_AFFINE sched_domain", should it be "suitable for local cpu and
prev cpu" becasue you only check the capacity of these 2 CPUs.
Other than this comment for the commit message, the patch looks good to me
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
> balancing take over (find_idlest_{group, cpu}()).
>
> This patch makes affine wake-ups conditional on whether both the waker
> cpu and prev_cpu has sufficient capacity for the waking task, or not.
>
> It is assumed that the sched_group(s) containing the waker cpu and
> prev_cpu only contain cpu with the same capacity (homogeneous).
>
> Ideally, we shouldn't set 'want_affine' in the first place, but we don't
> know if SD_BALANCE_WAKE is enabled on the sched_domain(s) until we start
> traversing them.
>
> cc: Ingo Molnar <mingo@redhat.com>
> cc: Peter Zijlstra <peterz@infradead.org>
>
> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> ---
> kernel/sched/fair.c | 28 +++++++++++++++++++++++++++-
> 1 file changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 216db302e87d..dba02c7b57b3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -114,6 +114,12 @@ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
> unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
> #endif
>
> +/*
> + * The margin used when comparing utilization with cpu capacity:
> + * util * 1024 < capacity * margin
> + */
> +unsigned int capacity_margin = 1280; /* ~20% */
> +
> static inline void update_load_add(struct load_weight *lw, unsigned long inc)
> {
> lw->weight += inc;
> @@ -5260,6 +5266,25 @@ static int cpu_util(int cpu)
> return (util >= capacity) ? capacity : util;
> }
>
> +static inline int task_util(struct task_struct *p)
> +{
> + return p->se.avg.util_avg;
> +}
> +
> +static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
> +{
> + long min_cap, max_cap;
> +
> + min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu));
> + max_cap = cpu_rq(cpu)->rd->max_cpu_capacity;
> +
> + /* Minimum capacity is close to max, no need to abort wake_affine */
> + if (max_cap - min_cap < max_cap >> 3)
> + return 0;
> +
> + return min_cap * 1024 < task_util(p) * capacity_margin;
> +}
> +
> /*
> * select_task_rq_fair: Select target runqueue for the waking task in domains
> * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
> @@ -5283,7 +5308,8 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
>
> if (sd_flag & SD_BALANCE_WAKE) {
> record_wakee(p);
> - want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, tsk_cpus_allowed(p));
> + want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu)
> + && cpumask_test_cpu(cpu, tsk_cpus_allowed(p));
> }
>
> rcu_read_lock();
> --
> 1.9.1
>
next prev parent reply other threads:[~2016-07-13 12:57 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-22 17:03 [PATCH v2 00/13] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 01/13] sched: Fix power to capacity renaming in comment Morten Rasmussen
2016-08-10 18:03 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 02/13] sched/fair: Consistent use of prev_cpu in wakeup path Morten Rasmussen
2016-06-22 18:04 ` Rik van Riel
2016-06-23 9:56 ` Morten Rasmussen
2016-06-23 12:24 ` Rik van Riel
2016-08-10 18:03 ` [tip:sched/core] sched/fair: Make the use of prev_cpu consistent in the " tip-bot for Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 03/13] sched/fair: Optimize find_idlest_cpu() when there is no choice Morten Rasmussen
2016-07-13 12:20 ` Vincent Guittot
2016-08-10 18:03 ` [tip:sched/core] " tip-bot for Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 04/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Morten Rasmussen
2016-07-11 9:55 ` Peter Zijlstra
2016-07-11 10:42 ` Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 05/13] sched: Enable SD_BALANCE_WAKE for asymmetric capacity systems Morten Rasmussen
2016-07-11 10:04 ` Peter Zijlstra
2016-07-11 10:37 ` Morten Rasmussen
2016-07-11 11:04 ` Morten Rasmussen
2016-07-11 11:24 ` Peter Zijlstra
2016-07-12 14:26 ` Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 06/13] sched: Store maximum per-cpu capacity in root domain Morten Rasmussen
2016-07-11 10:18 ` Peter Zijlstra
2016-07-11 16:16 ` Dietmar Eggemann
2016-07-12 11:42 ` Peter Zijlstra
2016-07-13 11:18 ` Dietmar Eggemann
2016-07-13 12:40 ` Vincent Guittot
2016-07-13 13:48 ` Dietmar Eggemann
2016-07-13 16:37 ` Morten Rasmussen
2016-07-14 13:25 ` Vincent Guittot
2016-07-14 15:15 ` Morten Rasmussen
2016-07-15 11:46 ` Morten Rasmussen
2016-07-15 13:39 ` Vincent Guittot
2016-07-15 16:02 ` Morten Rasmussen
2016-07-18 12:48 ` Vincent Guittot
2016-07-18 15:11 ` Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 07/13] sched/fair: Let asymmetric cpu configurations balance at wake-up Morten Rasmussen
2016-07-11 11:13 ` Peter Zijlstra
2016-07-11 12:32 ` Morten Rasmussen
2016-07-13 12:56 ` Vincent Guittot [this message]
2016-07-13 16:14 ` Morten Rasmussen
2016-07-14 13:45 ` Vincent Guittot
2016-07-15 8:37 ` Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 08/13] sched/fair: Compute task/cpu utilization at wake-up more correctly Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 09/13] sched/fair: Consider spare capacity in find_idlest_group() Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 10/13] sched: Add per-cpu max capacity to sched_group_capacity Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 11/13] sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups Morten Rasmussen
2016-06-23 21:20 ` Sai Gurrappadi
2016-06-30 7:49 ` Morten Rasmussen
2016-07-14 16:39 ` Sai Gurrappadi
2016-07-15 8:39 ` Morten Rasmussen
2016-07-12 12:59 ` Peter Zijlstra
2016-07-12 14:34 ` Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 12/13] arm: Set SD_ASYM_CPUCAPACITY for big.LITTLE platforms Morten Rasmussen
2016-06-22 17:03 ` [PATCH v2 13/13] arm: Update arch_scale_cpu_capacity() to reflect change to define Morten Rasmussen
2016-06-28 10:20 ` [PATCH v2 00/13] sched: Clean-ups and asymmetric cpu capacity support Koan-Sin Tan
2016-06-30 7:53 ` Morten Rasmussen
2016-07-08 7:35 ` KEITA KOBAYASHI
2016-07-08 8:18 ` Morten Rasmussen
2016-07-11 8:33 ` Morten Rasmussen
2016-07-11 12:44 ` Vincent Guittot
2016-07-12 13:25 ` Peter Zijlstra
2016-07-12 14:39 ` Morten Rasmussen
2016-07-13 12:06 ` Vincent Guittot
2016-07-13 15:54 ` Morten Rasmussen
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