Hello, Tao.
On Tue, 08 Sep 2026 18:01:35 +0800, Tao Cui wrote:
4. One model system-wide vs named models selectable per device (as
tcp-cc names are per-socket)?
The struct_ops instance should be per-device. Loading a model for a device
should switch it to BPF automatically. Switching back to the builtin model
should detach the struct_ops.
2. Per-cgroup state lifetime: iocg_id is the css id and is recycled
once the cgroup is removed, so models must treat it as a
transient key. Does the interface need a release(iocg_id)
callback so models can clean up per-cgroup state instead of
detecting reuse, or is per-cgroup bpf local storage, which
carries its own lifetime, the better home for model state?
I'd pass blkcg as a kptr and add online/offline callbacks so the model can
manage its per-cgroup state.
return value of 0 delegates the IO back to the builtin formula, so a
model which only handles some IO types cannot make the rest free.
I don't think mixing BPF and builtin pricing makes sense, either per IO or
between charging and request sizing. It seems convoluted and error-prone.
Implementing the linear model in BPF is straightforward.
Please combine the interface, registration, dispatch and configuration
changes into one patch. These patches are small and implement one feature.
Thanks.
--
tejun