linux-kernel - [RFC PATCH v1 7/8] sched/sched.h: move arch_scale_{freq,cpu}_capacity outside CONFIG

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Date:   Wed,  5 Jul 2017 09:59:04 +0100
From:   Juri Lelli <juri.lelli@....com>
To:     peterz@...radead.org, mingo@...hat.com, rjw@...ysocki.net,
        viresh.kumar@...aro.org
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        tglx@...utronix.de, vincent.guittot@...aro.org,
        rostedt@...dmis.org, luca.abeni@...tannapisa.it,
        claudio@...dence.eu.com, tommaso.cucinotta@...tannapisa.it,
        bristot@...hat.com, mathieu.poirier@...aro.org, tkjos@...roid.com,
        joelaf@...gle.com, andresoportus@...gle.com,
        morten.rasmussen@....com, dietmar.eggemann@....com,
        patrick.bellasi@....com, juri.lelli@....com,
        Ingo Molnar <mingo@...nel.org>
Subject: [RFC PATCH v1 7/8] sched/sched.h: move arch_scale_{freq,cpu}_capacity outside CONFIG_SMP

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.

Signed-off-by: Juri Lelli <juri.lelli@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.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
-- 
2.11.0