linux-kernel - [PATCH v2 1/3] sched: Introduce sched_asym_cpucap

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Message-Id: <20220729111305.1275158-2-dietmar.eggemann@arm.com>
Date:   Fri, 29 Jul 2022 13:13:03 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Mel Gorman <mgorman@...e.de>, Ben Segall <bsegall@...gle.com>,
        Luca Abeni <luca.abeni@...tannapisa.it>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] sched: Introduce sched_asym_cpucap_active()

Create an inline helper for conditional code to be only executed on
asymmetric CPU capacity systems. This makes these (currently ~10 and
future) conditions a lot more readable.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
 kernel/sched/cpudeadline.c | 2 +-
 kernel/sched/deadline.c    | 4 ++--
 kernel/sched/fair.c        | 8 ++++----
 kernel/sched/rt.c          | 4 ++--
 kernel/sched/sched.h       | 5 +++++
 5 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 02d970a879ed..57c92d751bcd 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -123,7 +123,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
 		unsigned long cap, max_cap = 0;
 		int cpu, max_cpu = -1;
 
-		if (!static_branch_unlikely(&sched_asym_cpucapacity))
+		if (!sched_asym_cpucap_active())
 			return 1;
 
 		/* Ensure the capacity of the CPUs fits the task. */
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 5867e186c39a..3f9d90b8a8b6 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -144,7 +144,7 @@ static inline unsigned long __dl_bw_capacity(int i)
  */
 static inline unsigned long dl_bw_capacity(int i)
 {
-	if (!static_branch_unlikely(&sched_asym_cpucapacity) &&
+	if (!sched_asym_cpucap_active() &&
 	    capacity_orig_of(i) == SCHED_CAPACITY_SCALE) {
 		return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
 	} else {
@@ -1846,7 +1846,7 @@ select_task_rq_dl(struct task_struct *p, int cpu, int flags)
 	 * Take the capacity of the CPU into account to
 	 * ensure it fits the requirement of the task.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity))
+	if (sched_asym_cpucap_active())
 		select_rq |= !dl_task_fits_capacity(p, cpu);
 
 	if (select_rq) {
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2fc47257ae91..3b186c9c4ea1 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4262,7 +4262,7 @@ static inline int task_fits_capacity(struct task_struct *p,
 
 static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
 {
-	if (!static_branch_unlikely(&sched_asym_cpucapacity))
+	if (!sched_asym_cpucap_active())
 		return;
 
 	if (!p || p->nr_cpus_allowed == 1) {
@@ -6506,7 +6506,7 @@ select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
 
 static inline bool asym_fits_capacity(unsigned long task_util, int cpu)
 {
-	if (static_branch_unlikely(&sched_asym_cpucapacity))
+	if (sched_asym_cpucap_active())
 		return fits_capacity(task_util, capacity_of(cpu));
 
 	return true;
@@ -6526,7 +6526,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 	 * On asymmetric system, update task utilization because we will check
 	 * that the task fits with cpu's capacity.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity)) {
+	if (sched_asym_cpucap_active()) {
 		sync_entity_load_avg(&p->se);
 		task_util = uclamp_task_util(p);
 	}
@@ -6580,7 +6580,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 	 * For asymmetric CPU capacity systems, our domain of interest is
 	 * sd_asym_cpucapacity rather than sd_llc.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity)) {
+	if (sched_asym_cpucap_active()) {
 		sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target));
 		/*
 		 * On an asymmetric CPU capacity system where an exclusive
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 55f39c8f4203..054b6711e961 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -509,7 +509,7 @@ static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
 	unsigned int cpu_cap;
 
 	/* Only heterogeneous systems can benefit from this check */
-	if (!static_branch_unlikely(&sched_asym_cpucapacity))
+	if (!sched_asym_cpucap_active())
 		return true;
 
 	min_cap = uclamp_eff_value(p, UCLAMP_MIN);
@@ -1897,7 +1897,7 @@ static int find_lowest_rq(struct task_struct *task)
 	 * If we're on asym system ensure we consider the different capacities
 	 * of the CPUs when searching for the lowest_mask.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity)) {
+	if (sched_asym_cpucap_active()) {
 
 		ret = cpupri_find_fitness(&task_rq(task)->rd->cpupri,
 					  task, lowest_mask,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 73ae32898f25..72704b2b4a45 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1808,6 +1808,11 @@ DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 extern struct static_key_false sched_asym_cpucapacity;
 
+static __always_inline bool sched_asym_cpucap_active(void)
+{
+	return static_branch_unlikely(&sched_asym_cpucapacity);
+}
+
 struct sched_group_capacity {
 	atomic_t		ref;
 	/*
-- 
2.25.1