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Subject[PATCH 3/5] sched/fair: remove redundant check in select_idle_smt
Date
If two cpus share LLC cache, then the two cores they belong to
are also in the same LLC domain.

Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Reviewed-by: Josh Don <joshdon@google.com>
---
kernel/sched/fair.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c72093f282ec..0d7e8555bcf9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6339,14 +6339,11 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu
/*
* Scan the local SMT mask for idle CPUs.
*/
-static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
+static int select_idle_smt(struct task_struct *p, int target)
{
int cpu;

- for_each_cpu(cpu, cpu_smt_mask(target)) {
- if (!cpumask_test_cpu(cpu, p->cpus_ptr) ||
- !cpumask_test_cpu(cpu, sched_domain_span(sd)))
- continue;
+ for_each_cpu_and(cpu, cpu_smt_mask(target), p->cpus_ptr) {
if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
return cpu;
}
@@ -6370,7 +6367,7 @@ static inline int select_idle_core(struct task_struct *p, int core, struct cpuma
return __select_idle_cpu(core, p);
}

-static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
+static inline int select_idle_smt(struct task_struct *p, int target)
{
return -1;
}
@@ -6607,7 +6604,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
has_idle_core = test_idle_cores(target);

if (!has_idle_core && cpus_share_cache(prev, target)) {
- i = select_idle_smt(p, sd, prev);
+ i = select_idle_smt(p, prev);
if ((unsigned int)i < nr_cpumask_bits)
return i;
}
--
2.31.1
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