Commit da6833cf authored Jul 13, 2017 by Dietmar Eggemann Committed by Quentin Perret Feb 01, 2018

sched/fair: introduce an arch scaling function for max frequency capping



The max frequency scaling factor is defined as:

  max_freq_scale = policy_max_freq / cpuinfo_max_freq

To be able to scale the cpu capacity by this factor introduce a call to
the new arch scaling function arch_scale_max_freq_capacity() in
update_cpu_capacity() and provide a default implementation which returns
SCHED_CAPACITY_SCALE.

Another subsystem (e.g. cpufreq) can overwrite this default implementation,
exactly as for frequency and cpu invariance. It has to be enabled by the
arch by defining arch_scale_max_freq_capacity to the actual
implementation.

Change-Id: I266cd1f4c1c82f54b80063c36aa5f7662599dd28
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>

parent 19e1513f

kernel/sched/fair.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -8331,6 +8331,9 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu)

		cpu_rq(cpu)->cpu_capacity_orig = capacity;

		capacity *= arch_scale_max_freq_capacity(sd, cpu);
		capacity >>= SCHED_CAPACITY_SHIFT;

		mcc = &cpu_rq(cpu)->rd->max_cpu_capacity;

		raw_spin_lock_irqsave(&mcc->lock, flags);

kernel/sched/sched.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -1583,6 +1583,14 @@ unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu)
		}
		#endif

		#ifndef arch_scale_max_freq_capacity
		static __always_inline
		unsigned long arch_scale_max_freq_capacity(struct sched_domain *sd, int cpu)
		{
		return SCHED_CAPACITY_SCALE;
		}
		#endif

		#ifndef arch_scale_cpu_capacity
		static __always_inline
		unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)