diff options
| -rw-r--r-- | kernel/sched/ext.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 7043fb941130..bfe923b7ffe0 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -8212,7 +8212,7 @@ __bpf_kfunc void scx_bpf_dispatch_cancel(const struct bpf_prog_aux *aux) /** * scx_bpf_dsq_move_to_local - move a task from a DSQ to the current CPU's local DSQ - * @dsq_id: DSQ to move task from + * @dsq_id: DSQ to move task from. Must be a user-created DSQ * @aux: implicit BPF argument to access bpf_prog_aux hidden from BPF progs * @enq_flags: %SCX_ENQ_* * @@ -8220,6 +8220,14 @@ __bpf_kfunc void scx_bpf_dispatch_cancel(const struct bpf_prog_aux *aux) * local DSQ for execution with @enq_flags applied. Can only be called from * ops.dispatch(). * + * Built-in DSQs (%SCX_DSQ_GLOBAL and %SCX_DSQ_LOCAL*) are not supported as + * sources. Local DSQs support reenqueueing (a task can be picked up for + * execution, dequeued for property changes, or reenqueued), but the BPF + * scheduler cannot directly iterate or move tasks from them. %SCX_DSQ_GLOBAL + * is similar but also doesn't support reenqueueing, as it maps to multiple + * per-node DSQs making the scope difficult to define; this may change in the + * future. + * * This function flushes the in-flight dispatches from scx_bpf_dsq_insert() * before trying to move from the specified DSQ. It may also grab rq locks and * thus can't be called under any BPF locks. |