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| author | Michael Turquette <mturquette+renesas@baylibre.com> | 2016-03-09 15:18:27 -0800 |
|---|---|---|
| committer | Michael Turquette <mturquette+renesas@baylibre.com> | 2016-03-13 21:26:57 -0700 |
| commit | f701e4ee2dab992f7a195698381b772e7c1a4084 (patch) | |
| tree | ab4949754876a737fc28ae8293e755840c12aa75 | |
| parent | a4ccf611d8a1611c0be093cbd00f552d57fbd9ad (diff) | |
| download | linux-schedutil-v3-enhancements.tar.gz | |
sched: prefer cpufreq_scale_freq_capacityschedutil-v3-enhancements
arch_scale_freq_capacity is weird. It specifies an arch hook for an
implementation that could easily vary within an architecture or even a
chip family.
This patch helps to mitigate this weirdness by defaulting to the
cpufreq-provided implementation, which should work for all cases where
CONFIG_CPU_FREQ is set.
If CONFIG_CPU_FREQ is not set, then try to use an implementation
provided by the architecture. Failing that, fall back to
SCHED_CAPACITY_SCALE.
It may be desirable for cpufreq drivers to specify their own
implementation of arch_scale_freq_capacity in the future. The same is
true for platform code within an architecture. In both cases an
efficient implementation selector will need to be created and this patch
adds a comment to that effect.
Signed-off-by: Michael Turquette <mturquette+renesas@baylibre.com>
| -rw-r--r-- | kernel/sched/sched.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 469d11d197ca41..37502ea7882f46 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1368,7 +1368,21 @@ static inline int hrtick_enabled(struct rq *rq) #ifdef CONFIG_SMP extern void sched_avg_update(struct rq *rq); -#ifndef arch_scale_freq_capacity +/* + * arch_scale_freq_capacity can be implemented by cpufreq, platform code or + * arch code. We select the cpufreq-provided implementation first. If it + * doesn't exist then we default to any other implementation provided from + * platform/arch code. If those do not exist then we use the default + * SCHED_CAPACITY_SCALE value below. + * + * Note that if cpufreq drivers or platform/arch code have competing + * implementations it is up to those subsystems to select one at runtime with + * an efficient solution, as we cannot tolerate the overhead of indirect + * functions (e.g. function pointers) in the scheduler fast path + */ +#ifdef CONFIG_CPU_FREQ +#define arch_scale_freq_capacity cpufreq_scale_freq_capacity +#elif !defined(arch_scale_freq_capacity) static __always_inline unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu) { |