linux-kernel - [RFC PATCH 1/6] sched/fair: Create util_fits

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Message-Id: <20180320094312.24081-2-dietmar.eggemann@arm.com>
Date:   Tue, 20 Mar 2018 09:43:07 +0000
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Quentin Perret <quentin.perret@....com>,
        Thara Gopinath <thara.gopinath@...aro.org>
Cc:     linux-pm@...r.kernel.org,
        Morten Rasmussen <morten.rasmussen@....com>,
        Chris Redpath <chris.redpath@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Valentin Schneider <valentin.schneider@....com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Todd Kjos <tkjos@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>
Subject: [RFC PATCH 1/6] sched/fair: Create util_fits_capacity()

The functionality that a given utilization fits into a given capacity
is factored out into a separate function.

Currently it is only used in wake_cap() but will be re-used to figure
out if a cpu or a scheduler group is over-utilized.

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
 kernel/sched/fair.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3582117e1580..bf7b485ddf60 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6374,6 +6374,11 @@ static unsigned long cpu_util_wake(int cpu, struct task_struct *p)
 	return (util >= capacity) ? capacity : util;
 }
 
+static inline int util_fits_capacity(unsigned long util, unsigned long capacity)
+{
+	return capacity * 1024 > util * capacity_margin;
+}
+
 /*
  * Disable WAKE_AFFINE in the case where task @p doesn't fit in the
  * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu.
@@ -6395,7 +6400,7 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
 	/* Bring task utilization in sync with prev_cpu */
 	sync_entity_load_avg(&p->se);
 
-	return min_cap * 1024 < task_util(p) * capacity_margin;
+	return !util_fits_capacity(task_util(p), min_cap);
 }
 
 /*
-- 
2.11.0