Hi Peter,
On Fri, 20 Jul 2018 at 14:31, Peter Zijlstra <pet...@infradead.org> wrote:
>
> On Thu, Jul 19, 2018 at 02:00:06PM +0200, Vincent Guittot wrote:
> > 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
>
> So much for compilers.... I though those things were supposed to be
> 'clever'.
>
> > +#if defined(SMP) \
> > + && (defined(CONFIG_IRQ_TIME_ACCOUNTING) ||
> > defined(CONFIG_PARAVIRT_TIME_ACCOUNTING))
>
> That's atrocious :-)
>
> Fixed it with the below.
Thanks for the fix
>
>
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -135,7 +135,7 @@ static void update_rq_clock_task(struct
> * In theory, the compile should just see 0 here, and optimize out the call
> * to sched_rt_avg_update. But I don't trust it...
> */
> -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) ||
> defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> +#ifdef HAVE_SCHED_AVG_IRQ
> s64 steal = 0, irq_delta = 0;
> #endif
> #ifdef CONFIG_IRQ_TIME_ACCOUNTING
> @@ -177,7 +177,7 @@ static void update_rq_clock_task(struct
>
> rq->clock_task += delta;
>
> -#if defined(CONFIG_IRQ_TIME_ACCOUNTING) ||
> defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> +#ifdef HAVE_SCHED_AVG_IRQ
> if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
> update_irq_load_avg(rq, irq_delta + steal);
> #endif
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -856,6 +856,7 @@ struct rq {
> struct sched_avg avg_rt;
> struct sched_avg avg_dl;
> #if defined(CONFIG_IRQ_TIME_ACCOUNTING) ||
> defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
> +#define HAVE_SCHED_AVG_IRQ
> struct sched_avg avg_irq;
> #endif
> u64 idle_stamp;
> @@ -2212,8 +2213,7 @@ static inline unsigned long cpu_util_rt(
> }
> #endif
>
> -#if defined(SMP) \
> - && (defined(CONFIG_IRQ_TIME_ACCOUNTING) ||
> defined(CONFIG_PARAVIRT_TIME_ACCOUNTING))
> +#ifdef HAVE_SCHED_AVG_IRQ
> static inline unsigned long cpu_util_irq(struct rq *rq)
> {
> return rq->avg_irq.util_avg;
