From: Morten Rasmussen <morten.rasmussen@arm.com>
To: peterz@infradead.org, mingo@redhat.com
Cc: valentin.schneider@arm.com, dietmar.eggemann@arm.com,
vincent.guittot@linaro.org, gaku.inami.xh@renesas.com,
linux-kernel@vger.kernel.org,
Morten Rasmussen <morten.rasmussen@arm.com>
Subject: [PATCHv3 1/9] sched: Add static_key for asymmetric cpu capacity optimizations
Date: Wed, 20 Jun 2018 10:05:41 +0100 [thread overview]
Message-ID: <1529485549-5191-2-git-send-email-morten.rasmussen@arm.com> (raw)
In-Reply-To: <1529485549-5191-1-git-send-email-morten.rasmussen@arm.com>
The existing asymmetric cpu capacity code should cause minimal overhead
for others. Putting it behind a static_key, it has been done for SMT
optimizations, would make it easier to extend and improve without
causing harm to others moving forward.
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 | 3 +++
kernel/sched/sched.h | 1 +
kernel/sched/topology.c | 18 ++++++++++++++++++
3 files changed, 22 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e497c05aab7f..6116d1b7e441 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6585,6 +6585,9 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
{
long min_cap, max_cap;
+ if (!static_branch_unlikely(&sched_asym_cpucapacity))
+ return 0;
+
min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu));
max_cap = cpu_rq(cpu)->rd->max_cpu_capacity;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 67702b4d9ac7..0fbfbcf5c551 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1153,6 +1153,7 @@ DECLARE_PER_CPU(int, sd_llc_id);
DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
DECLARE_PER_CPU(struct sched_domain *, sd_numa);
DECLARE_PER_CPU(struct sched_domain *, sd_asym);
+extern struct static_key_false sched_asym_cpucapacity;
struct sched_group_capacity {
atomic_t ref;
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 61a1125c1ae4..edc87e35fc75 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -398,6 +398,7 @@ DEFINE_PER_CPU(int, sd_llc_id);
DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
DEFINE_PER_CPU(struct sched_domain *, sd_asym);
+DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
static void update_top_cache_domain(int cpu)
{
@@ -425,6 +426,21 @@ static void update_top_cache_domain(int cpu)
rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
}
+static void update_asym_cpucapacity(int cpu)
+{
+ int enable = false;
+
+ rcu_read_lock();
+ if (lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY))
+ enable = true;
+ rcu_read_unlock();
+
+ if (enable) {
+ /* This expects to be hotplug-safe */
+ static_branch_enable_cpuslocked(&sched_asym_cpucapacity);
+ }
+}
+
/*
* Attach the domain 'sd' to 'cpu' as its base domain. Callers must
* hold the hotplug lock.
@@ -1707,6 +1723,8 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
}
rcu_read_unlock();
+ update_asym_cpucapacity(cpumask_first(cpu_map));
+
if (rq && sched_debug_enabled) {
pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
--
2.7.4
next prev parent reply other threads:[~2018-06-20 9:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-20 9:05 [PATCHv3 0/9] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Morten Rasmussen
2018-06-20 9:05 ` Morten Rasmussen [this message]
2018-06-22 8:22 ` [PATCHv3 1/9] sched: Add static_key for asymmetric cpu capacity optimizations Quentin Perret
2018-06-22 14:36 ` Morten Rasmussen
2018-06-27 15:41 ` Dietmar Eggemann
2018-06-28 8:48 ` Morten Rasmussen
2018-06-28 17:16 ` Dietmar Eggemann
2018-07-02 8:36 ` Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 2/9] sched/fair: Add group_misfit_task load-balance type Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 3/9] sched: Add sched_group per-cpu max capacity Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 4/9] sched/fair: Consider misfit tasks when load-balancing Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 5/9] sched/fair: Kick nohz balance if rq->misfit_task Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 6/9] sched: Change root_domain->overload type to int Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 7/9] sched: Wrap rq->rd->overload accesses with READ/WRITE_ONCE Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 8/9] sched/fair: Set sd->overload when misfit Morten Rasmussen
2018-06-20 9:05 ` [PATCHv3 9/9] sched/fair: Don't move tasks to lower capacity cpus unless necessary Morten Rasmussen
2018-07-03 2:28 ` [PATCHv3 0/9] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Gaku Inami
2018-07-04 10:33 ` Morten Rasmussen
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