Re: [RFC][PATCH] sched/ext: Split curr|donor references properly

[Tejun Heo <tj@kernel.org>]

Hello,

On Sat, Dec 06, 2025 at 09:56:50AM -0500, Joel Fernandes wrote:
...
> At a high level, my understanding is BPF schedulers have a lot of say in how to
> schedule including precise time slice and preemption control (give or take level
> of control and performance reasons). You can in fact have your own 'userland'
> queues that the kernel is unaware, IIUC. I am not sure if proxy exec will
> transparently work for all those usecases. It will probably work properly only
> when BPF scheduling in userland is simple and most of the scheduling is done by
> non-BPF kernel code.

Maybe this can be resolved by proxy execution explicitly telling sched_ext
to essentially dequeue the proxy-executed task so that it's kept more
transparent. However, I wonder whether it'd be a useful first step to first
deconflict the two config options. ie. Allow sched_ext loading disable proxy
execution dynamically so that people don't have to choose between the two
config options. I don't know the code intimately, but, from just skimming
it, it looks like it can be drained with a static key and some percpu
counters.

Thanks.

-- 
tejun