sched/fair: Remove redundant check in select_idle_smt()

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Don <joshdon@google.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20220907112000.1854-2-wuyun.abel@bytedance.com

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index efceb670e755b63b5d5ec97f3ff999f621d767e8..9657c7de5f576a17c4f7c878dde383bef03d8938 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6350,14 +6350,11 @@ 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;
        }
@@ -6381,7 +6378,7 @@ 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;
 }
@@ -6615,7 +6612,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
                has_idle_core = test_idle_cores(target, false);
 
                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;
                }