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Subject[PATCH] sched: Use non-atomic cpumask_{set,clear}_cpu()
Date
The cpumasks updated here are not subject to concurrency and using
atomic bitops for them is pointless and expensive. Use the non-atomic
variants instead.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
kernel/sched/fair.c | 6 +++---
kernel/sched/isolation.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8abd1c271499..8213ff6e365d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6097,7 +6097,7 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
bool idle = true;

for_each_cpu(cpu, cpu_smt_mask(core)) {
- cpumask_clear_cpu(cpu, cpus);
+ __cpumask_clear_cpu(cpu, cpus);
if (!available_idle_cpu(cpu))
idle = false;
}
@@ -9105,7 +9105,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,
if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {

/* Prevent to re-select dst_cpu via env's CPUs */
- cpumask_clear_cpu(env.dst_cpu, env.cpus);
+ __cpumask_clear_cpu(env.dst_cpu, env.cpus);

env.dst_rq = cpu_rq(env.new_dst_cpu);
env.dst_cpu = env.new_dst_cpu;
@@ -9132,7 +9132,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,

/* All tasks on this runqueue were pinned by CPU affinity */
if (unlikely(env.flags & LBF_ALL_PINNED)) {
- cpumask_clear_cpu(cpu_of(busiest), cpus);
+ __cpumask_clear_cpu(cpu_of(busiest), cpus);
/*
* Attempting to continue load balancing at the current
* sched_domain level only makes sense if there are
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 81faddba9e20..b02d148e7672 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -80,7 +80,7 @@ static int __init housekeeping_setup(char *str, enum hk_flags flags)
cpumask_andnot(housekeeping_mask,
cpu_possible_mask, non_housekeeping_mask);
if (cpumask_empty(housekeeping_mask))
- cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
+ __cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
} else {
cpumask_var_t tmp;

--
2.20.1.321.g9e740568ce00
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