Re: [PATCH v2] docs/sched_ext: document that cgroup CPU knobs are scheduler-dependent

[Tejun Heo]

Hello,

On Wed, Aug 19, 2026 at 09:21:57AM +0800, Tao Cui wrote:
...
> +The fair class enforces cpu controller knobs such as ``cpu.max``,
> +``cpu.weight`` and ``cpu.idle`` in the kernel. sched_ext only passes
> +them to the BPF scheduler through ``ops.cgroup_set_weight()``,
> +``ops.cgroup_set_idle()``, ``ops.cgroup_set_bandwidth()`` and friends.
> +Whether and how a knob takes effect is up to the loaded scheduler: if
> +it doesn't implement the corresponding callback, the knob is ignored.
> +For example, none of scx_simple, scx_flatcg and scx_central implements
> +``ops.cgroup_set_bandwidth()``, so with them ``cpu.max`` has no effect
> +-- the cgroup runs at unlimited CPU with ``nr_throttled`` staying
> +at 0.

SCX doesn't have nr_throttled routing right now even for scheds that
implement cpu.max (scx_lavd is the only one right now AFAIK). I'd keep the
documentation more concise and generic. I don't think listing schedulers
that don't implement the feature or specifically pointing to nr_throttled is
all that useful given that most schedulers don't implement it right now.

Thanks.

-- 
tejun