[RFCv5 PATCH 39/46] sched/cpufreq_sched: use static key for cpu frequency selection

Morten Rasmussen
2015-07-07T18:56:19Z

From: Juri Lelli <juri.lelli@arm.com>

Introduce a static key to only affect scheduler hot paths when sched
governor is enabled.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
---
kernel/sched/cpufreq_sched.c | 14 ++++++++++++++
kernel/sched/fair.c | 1 +
kernel/sched/sched.h | 6 ++++++
3 files changed, 21 insertions(+)

diff --git a/kernel/sched/cpufreq_sched.c b/kernel/sched/cpufreq_sched.c
index 5020f24..2968f3a 100644
--- a/kernel/sched/cpufreq_sched.c
+++ b/kernel/sched/cpufreq_sched.c
@@ -203,6 +203,18 @@ void cpufreq_sched_set_cap(int cpu, unsigned long capacity)
return;
}

+static inline void set_sched_energy_freq(void)
+{
+ if (!sched_energy_freq())
+ static_key_slow_inc(&__sched_energy_freq);
+}
+
+static inline void clear_sched_energy_freq(void)
+{
+ if (sched_energy_freq())
+ static_key_slow_dec(&__sched_energy_freq);
+}
+
static int cpufreq_sched_start(struct cpufreq_policy *policy)
{
struct gov_data *gd;
@@ -243,6 +255,7 @@ static int cpufreq_sched_start(struct cpufreq_policy *policy)

policy->governor_data = gd;
gd->policy = policy;
+ set_sched_energy_freq();
return 0;

err:
@@ -254,6 +267,7 @@ static int cpufreq_sched_stop(struct cpufreq_policy *policy)
{
struct gov_data *gd = policy->governor_data;

+ clear_sched_energy_freq();
if (cpufreq_driver_might_sleep()) {
kthread_stop(gd->task);
}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f7cb6c9..d395bc9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4282,6 +4282,7 @@ static inline void hrtick_update(struct rq *rq)
#endif

static bool cpu_overutilized(int cpu);
+struct static_key __sched_energy_freq __read_mostly = STATIC_KEY_INIT_FALSE;

/*
* The enqueue_task method is called before nr_running is
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 30aa0c4..b5e27d9 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1476,6 +1476,12 @@ unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
}
#endif

+extern struct static_key __sched_energy_freq;
+static inline bool sched_energy_freq(void)
+{
+ return static_key_false(&__sched_energy_freq);
+}
+
#ifdef CONFIG_CPU_FREQ_GOV_SCHED
void cpufreq_sched_set_cap(int cpu, unsigned long util);
#else
--
1.9.1