Re: [PATCH 5/5] docs: cgroup-v2: document the iocost BPF cost model attachment

[Tejun Heo <tj@kernel.org>]

Hello, Tao.

On Wed, Oct 28, 2026 at 10:35:34PM +0800, Tao Cui wrote:
> +	When CONFIG_BLK_CGROUP_IOCOST_BPF is enabled, a BPF cost
> +	model can be bound to a device by attaching an

Users can't select CONFIG_BLK_CGROUP_IOCOST_BPF.

> +	Only detaching removes the model, after which "model=bpf"
> +	fails and the device prices with the builtin model again.
> +	Device removal ejects the attached model as well, while the
> +	struct_ops link remains until userspace destroys it.  "ctrl"

"Only detaching removes the model" is followed by "Device removal ejects
the attached model as well".

> +	accepts only "auto" and "user" and never selects a model.  It
> +	keeps describing the builtin coefficients, which take effect
> +	again when switched back.  The automatic profile stepping does
> +	not switch profiles while the BPF model is in use; as with
> +	user-set parameters, the profile selected from the device
> +	class still applies.

cgroup-v2.rst doesn't describe automatic profile stepping anywhere else.

> +	defined.  They remain readable and writable while "model" is
> +	"bpf" but take effect only after switching back to "linear".

The builtin coefficients taking effect again after switching back is
already said above.

Thanks.

--
tejun