Commit fde7d647 authored by Andrea Righi's avatar Andrea Righi Committed by Tejun Heo
Browse files

sched_ext: idle: Fix scx_bpf_pick_any_cpu_node() behavior 



When %SCX_PICK_IDLE_IN_NODE is specified, scx_bpf_pick_any_cpu_node()
should always return a CPU from the specified node, regardless of its
idle state.

Also clarify this logic in the function documentation.

Fixes: 01059219 ("sched_ext: idle: Introduce node-aware idle cpu kfunc helpers")
Signed-off-by: default avatarAndrea Righi <arighi@nvidia.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 0e9b4c10

kernel/sched/ext_idle.c

+7 −3
Original line number Diff line number Diff line
@@ -1029,8 +1029,9 @@ __bpf_kfunc s32 scx_bpf_pick_idle_cpu(const struct cpumask *cpus_allowed, 
 * empty.

 *

 * The search starts from @node and proceeds to other online NUMA nodes in

 * order of increasing distance (unless SCX_PICK_IDLE_IN_NODE is specified,

 * in which case the search is limited to the target @node).

 * order of increasing distance (unless %SCX_PICK_IDLE_IN_NODE is specified,

 * in which case the search is limited to the target @node, regardless of

 * the CPU idle state).

 *

 * If ops.update_idle() is implemented and %SCX_OPS_KEEP_BUILTIN_IDLE is not

 * set, this function can't tell which CPUs are idle and will always pick any
@@ -1049,6 +1050,9 @@ __bpf_kfunc s32 scx_bpf_pick_any_cpu_node(const struct cpumask *cpus_allowed, 
	if (cpu >= 0)

		return cpu;



	if (flags & SCX_PICK_IDLE_IN_NODE)

		cpu = cpumask_any_and_distribute(cpumask_of_node(node), cpus_allowed);

	else

		cpu = cpumask_any_distribute(cpus_allowed);

	if (cpu < nr_cpu_ids)

		return cpu;