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

On 26/05/21 14:32, Peter Zijlstra wrote:

On Wed, May 26, 2021 at 12:14:20PM +0100, Valentin Schneider wrote:

quoted

---

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

quoted

@@ -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);

quoted

@@ -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.

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