Messages in this thread Patch in this message | | | From | Hao Jia <> | Subject | [PATCH 2/2] sched/core: Optimize the order of scanning CPU | Date | Fri, 21 Oct 2022 14:15:58 +0800 |
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When select_idle_capacity() starts scanning for an idle CPU, it starts with target CPU that has already been checked in select_idle_sibling(). So, we finally try the target CPU. Similarly for task_numa_assign(), we have just checked numa_migrate_on of dst_cpu, so start from the next CPU. This also works for steal_cookie_task(), the first scan must fail and start directly from the next one.
Signed-off-by: Hao Jia <jiahao.os@bytedance.com> --- kernel/sched/core.c | 2 +- kernel/sched/fair.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5800b0623ff3..f6ad68714546 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6154,7 +6154,7 @@ static bool steal_cookie_task(int cpu, struct sched_domain *sd) { int i; - for_each_cpu_wrap(i, sched_domain_span(sd), cpu) { + for_each_cpu_wrap(i, sched_domain_span(sd), cpu + 1) { if (i == cpu) continue; diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b7cbec539c77..d95ee285734e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1824,7 +1824,7 @@ static void task_numa_assign(struct task_numa_env *env, int start = env->dst_cpu; /* Find alternative idle CPU. */ - for_each_cpu_wrap(cpu, cpumask_of_node(env->dst_nid), start) { + for_each_cpu_wrap(cpu, cpumask_of_node(env->dst_nid), start + 1) { if (cpu == env->best_cpu || !idle_cpu(cpu) || !cpumask_test_cpu(cpu, env->p->cpus_ptr)) { continue; @@ -6663,7 +6663,7 @@ select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target) task_util = uclamp_task_util(p); - for_each_cpu_wrap(cpu, cpus, target) { + for_each_cpu_wrap(cpu, cpus, target + 1) { unsigned long cpu_cap = capacity_of(cpu); if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu)) -- 2.37.0
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