Commit 97e13ecb authored by Andrea Righi's avatar Andrea Righi Committed by Tejun Heo
Browse files

sched_ext: Skip per-CPU tasks in scx_bpf_reenqueue_local() 



scx_bpf_reenqueue_local() can be invoked from ops.cpu_release() to give
tasks that are queued to the local DSQ a chance to migrate to other
CPUs, when a CPU is taken by a higher scheduling class.

However, there is no point re-enqueuing tasks that can only run on that
particular CPU, as they would simply be re-added to the same local DSQ
without any benefit.

Therefore, skip per-CPU tasks in scx_bpf_reenqueue_local().

Signed-off-by: default avatarAndrea Righi <arighi@nvidia.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 71d07880

kernel/sched/ext.c

+5 −1
Original line number Diff line number Diff line
@@ -6621,8 +6621,12 @@ __bpf_kfunc u32 scx_bpf_reenqueue_local(void) 
		 * CPUs disagree, they use %ENQUEUE_RESTORE which is bypassed to

		 * the current local DSQ for running tasks and thus are not

		 * visible to the BPF scheduler.

		 *

		 * Also skip re-enqueueing tasks that can only run on this

		 * CPU, as they would just be re-added to the same local

		 * DSQ without any benefit.

		 */

		if (p->migration_pending)

		if (p->migration_pending || is_migration_disabled(p) || p->nr_cpus_allowed == 1)

			continue;



		dispatch_dequeue(rq, p);