Commit 3e6efe87 authored by Abel Wu's avatar Abel Wu Committed by Peter Zijlstra
Browse files

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: default avatarAbel Wu <wuyun.abel@bytedance.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarJosh Don <joshdon@google.com>
Acked-by: default avatarMel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20220907112000.1854-2-wuyun.abel@bytedance.com
parent 33f93525

kernel/sched/fair.c

+4 −7
Original line number Diff line number Diff line
@@ -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;

		}