Re: [RFC PATCH v1 7/8] sched/sched.h: move arch_scale_{freq,cpu}_capacity outside CONFIG_SMP

Steven Rostedt
2017-07-07T22:05:04Z

On Wed, 5 Jul 2017 09:59:04 +0100
Juri Lelli <juri.lelli@arm.com> wrote:

> Currently, frequency and cpu capacity scaling is only performed on
> CONFIG_SMP systems (as CFS PELT signals are only present for such
> systems). However, other scheduling classes want to do freq/cpu scaling,
> and for !CONFIG_SMP configurations as well.
>
> arch_scale_freq_capacity is useful to implement frequency scaling even
> on !CONFIG_SMP platforms, so we simply move it outside CONFIG_SMP
> ifdeffery.
>
> Even if arch_scale_cpu_capacity is not useful on !CONFIG_SMP platforms,
> we make a default implementation available for such configurations anyway
> to simplify scheduler code doing CPU scale invariance.
>

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> Signed-off-by: Juri Lelli <juri.lelli@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> ---
> include/linux/sched/topology.h | 12 ++++++------
> kernel/sched/sched.h | 13 ++++++++++---
> 2 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> index 7d065abc7a47..953cf4f889ec 100644
> --- a/include/linux/sched/topology.h
> +++ b/include/linux/sched/topology.h
> @@ -6,6 +6,12 @@
> #include <linux/sched/idle.h>
>
> /*
> + * Increase resolution of cpu_capacity calculations
> + */
> +#define SCHED_CAPACITY_SHIFT SCHED_FIXEDPOINT_SHIFT
> +#define SCHED_CAPACITY_SCALE (1L << SCHED_CAPACITY_SHIFT)
> +
> +/*
> * sched-domains (multiprocessor balancing) declarations:
> */
> #ifdef CONFIG_SMP
> @@ -26,12 +32,6 @@
> #define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */
> #define SD_NUMA 0x4000 /* cross-node balancing */
>
> -/*
> - * Increase resolution of cpu_capacity calculations
> - */
> -#define SCHED_CAPACITY_SHIFT SCHED_FIXEDPOINT_SHIFT
> -#define SCHED_CAPACITY_SCALE (1L << SCHED_CAPACITY_SHIFT)
> -
> #ifdef CONFIG_SCHED_SMT
> static inline int cpu_smt_flags(void)
> {
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index ec5769288927..178f4a5df2fa 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1668,9 +1668,6 @@ static inline int hrtick_enabled(struct rq *rq)
>
> #endif /* CONFIG_SCHED_HRTICK */
>
> -#ifdef CONFIG_SMP
> -extern void sched_avg_update(struct rq *rq);
> -
> #ifndef arch_scale_freq_capacity
> static __always_inline
> unsigned long arch_scale_freq_capacity(int cpu)
> @@ -1679,6 +1676,9 @@ unsigned long arch_scale_freq_capacity(int cpu)
> }
> #endif
>
> +#ifdef CONFIG_SMP
> +extern void sched_avg_update(struct rq *rq);
> +
> #ifndef arch_scale_cpu_capacity
> static __always_inline
> unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
> @@ -1696,6 +1696,13 @@ static inline void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
> sched_avg_update(rq);
> }
> #else
> +#ifndef arch_scale_cpu_capacity
> +static __always_inline
> +unsigned long arch_scale_cpu_capacity(void __always_unused *sd, int cpu)
> +{
> + return SCHED_CAPACITY_SCALE;
> +}
> +#endif
> static inline void sched_rt_avg_update(struct rq *rq, u64 rt_delta) { }
> static inline void sched_avg_update(struct rq *rq) { }
> #endif