Thread (15 messages) 15 messages, 8 authors, 2020-07-29

Re: [PATCH v2 1/3] arch_topology, sched/core: Cleanup thermal pressure definition

From: Thara Gopinath <hidden>
Date: 2020-07-13 14:32:57
Also in: linux-pm, lkml


On 7/12/20 12:59 PM, Valentin Schneider wrote:
The following commit:

   14533a16c46d ("thermal/cpu-cooling, sched/core: Move the arch_set_thermal_pressure() API to generic scheduler code")

moved the definition of arch_set_thermal_pressure() to sched/core.c, but
kept its declaration in linux/arch_topology.h. When building e.g. an x86
kernel with CONFIG_SCHED_THERMAL_PRESSURE=y, cpufreq_cooling.c ends up
getting the declaration of arch_set_thermal_pressure() from
include/linux/arch_topology.h, which is somewhat awkward.

On top of this, sched/core.c unconditionally defines
o The thermal_pressure percpu variable
o arch_set_thermal_pressure()

while arch_scale_thermal_pressure() does nothing unless redefined by the
architecture.

arch_*() functions are meant to be defined by architectures, so revert the
aforementioned commit and re-implement it in a way that keeps
arch_set_thermal_pressure() architecture-definable, and doesn't define the
thermal pressure percpu variable for kernels that don't need
it (CONFIG_SCHED_THERMAL_PRESSURE=n).

Signed-off-by: Valentin Schneider <redacted>
---
Reviewed-by: Thara Gopinath <redacted>
quoted hunk ↗ jump to hunk
  arch/arm/include/asm/topology.h   |  3 ++-
  arch/arm64/include/asm/topology.h |  3 ++-
  drivers/base/arch_topology.c      | 11 +++++++++++
  include/linux/arch_topology.h     |  4 ++--
  include/linux/sched/topology.h    |  7 +++++++
  kernel/sched/core.c               | 11 -----------
  6 files changed, 24 insertions(+), 15 deletions(-)
diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
index 435aba289fc5..e0593cf095d0 100644
--- a/arch/arm/include/asm/topology.h
+++ b/arch/arm/include/asm/topology.h
@@ -16,8 +16,9 @@
  /* Enable topology flag updates */
  #define arch_update_cpu_topology topology_update_cpu_topology
  
-/* Replace task scheduler's default thermal pressure retrieve API */
+/* Replace task scheduler's default thermal pressure API */
  #define arch_scale_thermal_pressure topology_get_thermal_pressure
+#define arch_set_thermal_pressure   topology_set_thermal_pressure
  
  #else
  
diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
index 0cc835ddfcd1..e042f6527981 100644
--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h
@@ -34,8 +34,9 @@ void topology_scale_freq_tick(void);
  /* Enable topology flag updates */
  #define arch_update_cpu_topology topology_update_cpu_topology
  
-/* Replace task scheduler's default thermal pressure retrieve API */
+/* Replace task scheduler's default thermal pressure API */
  #define arch_scale_thermal_pressure topology_get_thermal_pressure
+#define arch_set_thermal_pressure   topology_set_thermal_pressure
  
  #include <asm-generic/topology.h>
  
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 4d0a0038b476..d14cab7dfa3c 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -54,6 +54,17 @@ void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
  	per_cpu(cpu_scale, cpu) = capacity;
  }
  
+DEFINE_PER_CPU(unsigned long, thermal_pressure);
+
+void arch_set_thermal_pressure(const struct cpumask *cpus,
+			       unsigned long th_pressure)
+{
+	int cpu;
+
+	for_each_cpu(cpu, cpus)
+		WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure);
+}
+
  static ssize_t cpu_capacity_show(struct device *dev,
  				 struct device_attribute *attr,
  				 char *buf)
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index 0566cb3314ef..69b1dabe39dc 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -39,8 +39,8 @@ static inline unsigned long topology_get_thermal_pressure(int cpu)
  	return per_cpu(thermal_pressure, cpu);
  }
  
-void arch_set_thermal_pressure(struct cpumask *cpus,
-			       unsigned long th_pressure);
+void topology_set_thermal_pressure(const struct cpumask *cpus,
+				   unsigned long th_pressure);
  
  struct cpu_topology {
  	int thread_id;
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index fb11091129b3..764222d637b7 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -232,6 +232,13 @@ unsigned long arch_scale_thermal_pressure(int cpu)
  }
  #endif
  
+#ifndef arch_set_thermal_pressure
+static __always_inline
+void arch_set_thermal_pressure(const struct cpumask *cpus,
+			       unsigned long th_pressure)
+{ }
+#endif
+
  static inline int task_node(const struct task_struct *p)
  {
  	return cpu_to_node(task_cpu(p));
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ff0519551188..90b44f3840e4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3731,17 +3731,6 @@ unsigned long long task_sched_runtime(struct task_struct *p)
  	return ns;
  }
  
-DEFINE_PER_CPU(unsigned long, thermal_pressure);
-
-void arch_set_thermal_pressure(struct cpumask *cpus,
-			       unsigned long th_pressure)
-{
-	int cpu;
-
-	for_each_cpu(cpu, cpus)
-		WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure);
-}
-
  /*
   * This function gets called by the timer code, with HZ frequency.
   * We call it with interrupts disabled.
-- 
Warm Regards
Thara

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