Re: [PATCH v7 01/22] sched: Favour predetermined active CPU as migration destination

Valentin Schneider
2021-05-26T14:12:40Z

On 26/05/21 14:32, Peter Zijlstra wrote:
> On Wed, May 26, 2021 at 12:14:20PM +0100, Valentin Schneider wrote:
>> ---
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index 5226cc26a095..cd447c9db61d 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>
>> @@ -1954,19 +1953,15 @@ static int migration_cpu_stop(void *data)
>> if (pending) {
>> p->migration_pending = NULL;
>> complete = true;
>>
>> if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask))
>> goto out;
>> }
>>
>> if (task_on_rq_queued(p))
>> + rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
>
>> @@ -2249,7 +2244,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
>> init_completion(&my_pending.done);
>> my_pending.arg = (struct migration_arg) {
>> .task = p,
>> + .dest_cpu = dest_cpu,
>> .pending = &my_pending,
>> };
>>
>> @@ -2257,6 +2252,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
>> } else {
>> pending = p->migration_pending;
>> refcount_inc(&pending->refs);
>> + pending->arg.dest_cpu = dest_cpu;
>> }
>> }
>
> Argh.. that might just work. But I'm thinking we wants comments this
> time around :-) This is even more subtle.

Lemme stare at it some more and sharpen my quill then.