On Wed, May 01, 2024 at 05:09:53AM -1000, Tejun Heo wrote: > BPF schedulers might not want to schedule certain tasks - e.g. kernel > threads. This patch adds p->scx.disallow which can be set by BPF schedulers > in such cases. The field can be changed anytime and setting it in > ops.prep_enable() guarantees that the task can never be scheduled by > sched_ext. Why ?!?! By leaving kernel threads fair, and fair sitting above the BPF thing, it is not dissimilar to promoting them to FIFO. They will instantly preempt the BPF thing and keep running for as long as they need. The only real difference between this and actual FIFO is the behaviour on contention. This seems like a very bad thing to have, and your 'changelog' has no justification what so ever.
