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sched/fair: Remove #ifdefs from scale_rt_capacity()

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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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1532001606-6689-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Vincent Guittot
2018-07-19 14:00:06 +02:00
committed by Ingo Molnar
parent 4765096f4f
commit 2e62c4743a
4 changed files with 23 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
kernel/sched/sched.h
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@@ -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;
@@ -2210,17 +2211,32 @@ 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)
#ifdef HAVE_SCHED_AVG_IRQ
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);
util /= max;
return util;
}
#else
static inline unsigned long cpu_util_irq(struct rq *rq)
{
return 0;
}
#endif
static inline
unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned long max)
{
return util;
}
#endif