From: tip-bot for Morten Rasmussen <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: hpa@zytor.com, mingo@kernel.org, vincent.guittot@linaro.org,
tglx@linutronix.de, peterz@infradead.org,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
morten.rasmussen@arm.com, efault@gmx.de
Subject: [tip:sched/core] sched/fair: Let asymmetric CPU configurations balance at wake-up
Date: Thu, 18 Aug 2016 03:58:42 -0700 [thread overview]
Message-ID: <tip-3273163c6775c4c21823985304c2364b08ca6ea2@git.kernel.org> (raw)
In-Reply-To: <1469453670-2660-10-git-send-email-morten.rasmussen@arm.com>
Commit-ID: 3273163c6775c4c21823985304c2364b08ca6ea2
Gitweb: http://git.kernel.org/tip/3273163c6775c4c21823985304c2364b08ca6ea2
Author: Morten Rasmussen <morten.rasmussen@arm.com>
AuthorDate: Mon, 25 Jul 2016 14:34:26 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 18 Aug 2016 11:26:56 +0200
sched/fair: Let asymmetric CPU configurations balance at wake-up
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 the waking CPU and the
previous CPU, and all CPUs within their respective
SD_SHARE_PKG_RESOURCES domains (sd_llc). If not, let wakeup balancing
take over (find_idlest_{group, cpu}()).
This patch makes affine wake-ups conditional on whether both the waker
CPU and the previous CPU has sufficient capacity for the waking task,
or not, assuming that the CPU capacities within an SD_SHARE_PKG_RESOURCES
domain (sd_llc) are homogeneous.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-10-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/fair.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index acdc351..61d4854 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;
@@ -5376,6 +5382,32 @@ 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;
+}
+
+/*
+ * Disable WAKE_AFFINE in the case where task @p doesn't fit in the
+ * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu.
+ *
+ * In that case WAKE_AFFINE doesn't make sense and we'll let
+ * BALANCE_WAKE sort things out.
+ */
+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,
@@ -5399,7 +5431,8 @@ 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();
next prev parent reply other threads:[~2016-08-18 10:59 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-25 13:34 [PATCH v3 00/13] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 01/13] sched: Fix power to capacity renaming in comment Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 02/13] sched/fair: Consistent use of prev_cpu in wakeup path Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 03/13] sched/fair: Optimize find_idlest_cpu() when there is no choice Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 04/13] sched/core: Remove unnecessary null-pointer check Morten Rasmussen
2016-08-18 10:56 ` [tip:sched/core] sched/core: Remove unnecessary NULL-pointer check tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 05/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Morten Rasmussen
2016-08-15 10:54 ` Peter Zijlstra
2016-08-15 11:43 ` Morten Rasmussen
2016-08-18 10:56 ` [tip:sched/core] sched/core: Clarify SD_flags comment tip-bot for Peter Zijlstra
2016-08-17 8:42 ` [PATCH v3 05/13] sched: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Wanpeng Li
2016-08-17 9:23 ` Morten Rasmussen
2016-08-17 9:26 ` Wanpeng Li
2016-08-18 10:56 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 06/13] sched/core: Pass child domain into sd_init Morten Rasmussen
2016-08-18 10:57 ` [tip:sched/core] sched/core: Pass child domain into sd_init() tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 07/13] sched: Enable SD_BALANCE_WAKE for asymmetric capacity systems Morten Rasmussen
2016-08-18 10:57 ` [tip:sched/core] sched/core: " tip-bot for Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 08/13] sched: Store maximum per-cpu capacity in root domain Morten Rasmussen
2016-08-01 18:53 ` Dietmar Eggemann
2016-08-16 12:24 ` Vincent Guittot
2016-08-18 10:58 ` [tip:sched/core] sched/core: Store maximum per-CPU " tip-bot for Dietmar Eggemann
2016-07-25 13:34 ` [PATCH v3 09/13] sched/fair: Let asymmetric cpu configurations balance at wake-up Morten Rasmussen
2016-08-15 13:39 ` Peter Zijlstra
2016-08-15 15:01 ` Morten Rasmussen
2016-08-15 15:10 ` Peter Zijlstra
2016-08-15 15:30 ` Morten Rasmussen
2016-08-18 10:58 ` tip-bot for Morten Rasmussen [this message]
2016-07-25 13:34 ` [PATCH v3 10/13] sched/fair: Compute task/cpu utilization at wake-up more correctly Morten Rasmussen
2016-08-15 14:23 ` Peter Zijlstra
2016-08-15 15:42 ` Morten Rasmussen
2016-08-18 8:40 ` Morten Rasmussen
2016-08-18 10:24 ` Morten Rasmussen
2016-08-18 11:46 ` Wanpeng Li
2016-08-18 13:45 ` Morten Rasmussen
2016-08-19 1:43 ` Wanpeng Li
2016-08-19 14:03 ` Morten Rasmussen
2016-08-22 1:48 ` Wanpeng Li
2016-08-22 11:29 ` Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 11/13] sched/fair: Consider spare capacity in find_idlest_group() Morten Rasmussen
2016-08-16 13:57 ` Vincent Guittot
2016-08-18 11:16 ` Morten Rasmussen
2016-08-18 12:28 ` Peter Zijlstra
2016-07-25 13:34 ` [PATCH v3 12/13] sched: Add per-cpu min capacity to sched_group_capacity Morten Rasmussen
2016-07-25 13:34 ` [PATCH v3 13/13] sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups Morten Rasmussen
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