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SubjectRe: [PATCH] sched/fair: remove #ifdefs from scale_rt_capacity
On 19-07-18, 14:00, Vincent Guittot wrote:
> Reuse cpu_util_irq() that has been defined for schedutil and set irq util
> to 0 when !CONFIG_IRQ_TIME_ACCOUNTING
>
> But the compiler is not able to optimize the sequence (at least with
> aarch64 GCC 7.2.1)
> free *= (max - irq);
> free /= max;
> when irq is fixed to 0
>
> Add a new inline function scale_irq_capacity() that will scale utilization
> when irq is accounted. Reuse this funciton in schedutil which applies
> similar formula.
>
> Suggested-by: Ingo Molnar <mingo@redhat.com>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> kernel/sched/cpufreq_schedutil.c | 3 +--
> kernel/sched/fair.c | 13 +++----------
> kernel/sched/sched.h | 20 ++++++++++++++++++--
> 3 files changed, 22 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 97dcd44..3fffad3 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -247,8 +247,7 @@ static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
> * U' = irq + ------- * U
> * max
> */
> - util *= (max - irq);
> - util /= max;
> + util = scale_irq_capacity(util, irq, max);
> util += irq;
>
> /*
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index d5f7d52..14c3fdd 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7551,16 +7551,12 @@ static unsigned long scale_rt_capacity(int cpu)
> struct rq *rq = cpu_rq(cpu);
> unsigned long max = arch_scale_cpu_capacity(NULL, cpu);
> unsigned long used, free;
> -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> unsigned long irq;
> -#endif
>
> -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> - irq = READ_ONCE(rq->avg_irq.util_avg);
> + irq = cpu_util_irq(rq);
>
> if (unlikely(irq >= max))
> return 1;
> -#endif
>
> used = READ_ONCE(rq->avg_rt.util_avg);
> used += READ_ONCE(rq->avg_dl.util_avg);
> @@ -7569,11 +7565,8 @@ static unsigned long scale_rt_capacity(int cpu)
> return 1;
>
> free = max - used;
> -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> - free *= (max - irq);
> - free /= max;
> -#endif
> - return free;
> +
> + return scale_irq_capacity(free, irq, max);
> }
>
> static void update_cpu_capacity(struct sched_domain *sd, int cpu)
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index ebb4b3c..b80c3fd 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -2210,17 +2210,33 @@ static inline unsigned long cpu_util_rt(struct rq *rq)
> {
> return READ_ONCE(rq->avg_rt.util_avg);
> }
> +#endif
>
> -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> +#if defined(SMP) \
> + && (defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING))
> static inline unsigned long cpu_util_irq(struct rq *rq)
> {
> return rq->avg_irq.util_avg;
> }
> +
> +static inline
> +unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned long max)
> +{
> + util *= (max - irq);

() can be dropped here.

Other than that:

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

--
viresh

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