From: Quentin Perret <quentin.perret@arm.com>
To: peterz@infradead.org, rjw@rjwysocki.net,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: gregkh@linuxfoundation.org, mingo@redhat.com,
dietmar.eggemann@arm.com, morten.rasmussen@arm.com,
chris.redpath@arm.com, patrick.bellasi@arm.com,
valentin.schneider@arm.com, vincent.guittot@linaro.org,
thara.gopinath@linaro.org, viresh.kumar@linaro.org,
tkjos@google.com, joel@joelfernandes.org, smuckle@google.com,
adharmap@codeaurora.org, skannan@codeaurora.org,
pkondeti@codeaurora.org, juri.lelli@redhat.com,
edubezval@gmail.com, srinivas.pandruvada@linux.intel.com,
currojerez@riseup.net, javi.merino@kernel.org,
quentin.perret@arm.com
Subject: [PATCH v8 09/15] sched: Introduce sched_energy_present static key
Date: Tue, 16 Oct 2018 11:15:07 +0100 [thread overview]
Message-ID: <20181016101513.26919-10-quentin.perret@arm.com> (raw)
In-Reply-To: <20181016101513.26919-1-quentin.perret@arm.com>
In order to make sure Energy Aware Scheduling (EAS) will not impact
systems where no Energy Model is available, introduce a static key
guarding the access to EAS code. Since EAS is enabled on a
per-root-domain basis, the static key is enabled when at least one root
domain meets all conditions for EAS.
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
---
kernel/sched/sched.h | 4 ++++
kernel/sched/topology.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index cba77f619e4e..9d6cf58a8aff 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2278,3 +2278,7 @@ unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned
#else
#define perf_domain_span(pd) NULL
#endif
+
+#ifdef CONFIG_SMP
+extern struct static_key_false sched_energy_present;
+#endif
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 8f5efab1c058..58bfda46ac07 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -201,6 +201,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
return 1;
}
+DEFINE_STATIC_KEY_FALSE(sched_energy_present);
#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
DEFINE_MUTEX(sched_energy_mutex);
bool sched_energy_update;
@@ -273,6 +274,35 @@ static void destroy_perf_domain_rcu(struct rcu_head *rp)
free_pd(pd);
}
+static void sched_energy_start(int ndoms_new, cpumask_var_t doms_new[])
+{
+ /*
+ * The conditions for EAS to start are checked during the creation of
+ * root domains. If one of them meets all conditions, it will have a
+ * non-null list of performance domains.
+ */
+ while (ndoms_new) {
+ if (cpu_rq(cpumask_first(doms_new[ndoms_new - 1]))->rd->pd)
+ goto enable;
+ ndoms_new--;
+ }
+
+ if (static_branch_unlikely(&sched_energy_present)) {
+ if (sched_debug())
+ pr_info("%s: stopping EAS\n", __func__);
+ static_branch_disable_cpuslocked(&sched_energy_present);
+ }
+
+ return;
+
+enable:
+ if (!static_branch_unlikely(&sched_energy_present)) {
+ if (sched_debug())
+ pr_info("%s: starting EAS\n", __func__);
+ static_branch_enable_cpuslocked(&sched_energy_present);
+ }
+}
+
/*
* EAS can be used on a root domain if it meets all the following conditions:
* 1. an Energy Model (EM) is available;
@@ -2187,6 +2217,7 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
match3:
;
}
+ sched_energy_start(ndoms_new, doms_new);
#endif
/* Remember the new sched domains: */
--
2.19.1
next prev parent reply other threads:[~2018-10-16 10:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-16 10:14 [PATCH v8 00/15] Energy Aware Scheduling Quentin Perret
2018-10-16 10:14 ` [PATCH v8 01/15] sched: Relocate arch_scale_cpu_capacity Quentin Perret
2018-10-16 10:15 ` [PATCH v8 02/15] sched/cpufreq: Prepare schedutil for Energy Aware Scheduling Quentin Perret
2018-10-16 10:15 ` [PATCH v8 03/15] PM: Introduce an Energy Model management framework Quentin Perret
2018-11-07 16:32 ` Vincent Guittot
2018-11-07 17:02 ` Quentin Perret
2018-11-07 18:02 ` Vincent Guittot
2018-10-16 10:15 ` [PATCH v8 04/15] PM / EM: Expose the Energy Model in sysfs Quentin Perret
2018-10-16 10:15 ` [PATCH v8 05/15] sched/topology: Reference the Energy Model of CPUs when available Quentin Perret
2018-10-16 10:15 ` [PATCH v8 06/15] sched/topology: Lowest CPU asymmetry sched_domain level pointer Quentin Perret
2018-10-16 10:15 ` [PATCH v8 07/15] sched/topology: Disable EAS on inappropriate platforms Quentin Perret
2018-10-16 10:15 ` [PATCH v8 08/15] sched/topology: Make Energy Aware Scheduling depend on schedutil Quentin Perret
2018-10-16 10:15 ` Quentin Perret [this message]
2018-10-16 10:15 ` [PATCH v8 10/15] sched: Introduce a sysctl for Energy Aware Scheduling Quentin Perret
2018-10-16 12:50 ` Juri Lelli
2018-10-16 13:36 ` Quentin Perret
2018-10-16 13:46 ` Juri Lelli
2018-10-16 10:15 ` [PATCH v8 11/15] sched/fair: Clean-up update_sg_lb_stats parameters Quentin Perret
2018-10-16 10:15 ` [PATCH v8 12/15] sched: Add over-utilization/tipping point indicator Quentin Perret
2018-10-16 10:15 ` [PATCH v8 13/15] sched/fair: Introduce an energy estimation helper function Quentin Perret
2018-10-16 10:15 ` [PATCH v8 14/15] sched/fair: Select an energy-efficient CPU on task wake-up Quentin Perret
2018-10-16 10:15 ` [PATCH v8 15/15] OPTIONAL: cpufreq: dt: Register an Energy Model Quentin Perret
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