Re: [PATCH 3/3] sched/fair: Ensure select housekeeping cpus in task_numa_find_cpu

[Chuyi Zhou]

在 2024/12/18 14:21, K Prateek Nayak 写道:
> Hello Chuyi,
>
> On 12/16/2024 5:53 PM, Chuyi Zhou wrote:
> > [..snip..]
> > @@ -2081,6 +2081,12 @@ numa_type numa_classify(unsigned int 
> > imbalance_pct,
> >       return node_fully_busy;
> >   }
> > +static inline bool numa_migrate_test_cpu(struct task_struct *p, int cpu)
> > +{
> > +    return cpumask_test_cpu(cpu, p->cpus_ptr) &&
> > +            housekeeping_cpu(cpu, HK_TYPE_DOMAIN);
> > +}
> > +
> >   #ifdef CONFIG_SCHED_SMT
> >   /* Forward declarations of select_idle_sibling helpers */
> >   static inline bool test_idle_cores(int cpu);
> > @@ -2168,7 +2174,7 @@ static void task_numa_assign(struct 
> > task_numa_env *env,
> >           /* Find alternative idle CPU. */
> >           for_each_cpu_wrap(cpu, cpumask_of_node(env->dst_nid), start 
> > + 1) {
>
> Can we just do:
>
>      for_each_cpu_and(cpu, cpumask_of_node(env->dst_nid), 
> housekeeping_cpumask(HK_TYPE_DOMAIN)) {
>          ...
>      }
>
> and avoid adding numa_migrate_test_cpu(). Thoughts?

Make sense, but now there doesn't seem to be an API like 
for_each_cpu_wrap_and().

Do you think the following is better?

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 855df103f4dd..4792ef672738 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2167,9 +2167,9 @@ 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 + 1) {
+               for_each_cpu_and(cpu, cpumask_of_node(env->dst_nid), 
housekeeping_cpumask(HK_TYPE_DOMAIN)) {
                        if (cpu == env->best_cpu || !idle_cpu(cpu) ||
-                           !cpumask_test_cpu(cpu, env->p->cpus_ptr)) {
+                               cpu == start || !cpumask_test_cpu(cpu, 
env->p->cpus_ptr)) {
                                continue;
                        }


Thanks.


> >               if (cpu == env->best_cpu || !idle_cpu(cpu) ||
> > -                !cpumask_test_cpu(cpu, env->p->cpus_ptr)) {
> > +                !numa_migrate_test_cpu(env->p, cpu)) {
> >                   continue;
> >               }
> > @@ -2480,7 +2486,7 @@ static void task_numa_find_cpu(struct 
> > task_numa_env *env,
> >       for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) {
>
> Same modifications can be made for this outer loop.