sched_ext: Document why built-in DSQs are unsupported sources in scx_bpf_dsq_move_to_local()

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Add a comment explaining the design intent behind rejecting built-in DSQs
(%SCX_DSQ_GLOBAL and %SCX_DSQ_LOCAL*) as sources. Local DSQs support
reenqueueing but the BPF scheduler cannot directly iterate or move tasks
from them. %SCX_DSQ_GLOBAL is similar but also doesn't support
reenqueueing because it maps to multiple per-node DSQs, making the scope
difficult to define.

Also annotate @dsq_id to make clear it must be a user-created DSQ.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

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Cheng-Yang Chou 2026-03-27 17:50:39 +08:00 • committed by Tejun Heo

parent d6edb15ad9

commit 238aa43f0b

1 changed files with 9 additions and 1 deletions

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kernel/sched/ext.c

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