From: Tao Cui <[email protected]> Document the named-model binding of io.cost.model in the io.cost.model section of the cgroup v2 documentation: the binding and restore syntax, the unknown-name rejection, the full-replacement semantics of a bound model and the unregister lifetime.
Signed-off-by: Tao Cui <[email protected]> --- Documentation/admin-guide/cgroup-v2.rst | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 8d2603751c51a..d9d82559e2bc6 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -2115,8 +2115,10 @@ IO Interface Files are defined. ===== ================================ - ctrl "auto" or "user" + ctrl "auto", "user" or "bpf" model The cost model in use - "linear" + or the name of the bound + model ===== ================================ When "ctrl" is "auto", the kernel may change all parameters @@ -2124,6 +2126,23 @@ IO Interface Files parameters are written to, "ctrl" become "user" and the automatic changes are disabled. + When CONFIG_BLK_CGROUP_IOCOST_BPF is enabled, a bound model is + read back as "ctrl=bpf model=<name>", and writing "ctrl=bpf" is + accepted as a no-op so a saved configuration can be restored as-is. + "model" also accepts + the name of a registered iocost_model_ops BPF struct_ops model: + "model=<name>" binds the model to the device and the model fully + replaces the builtin linear pricing, for every operation including + flushes; "model=linear" (or "ctrl=auto/user") restores the builtin + model. Writing an unknown name fails with ENOENT and nothing is + applied. Unregistering a model removes its name from the + registry; devices already bound keep using it, and keep receiving + cgroup lifecycle notifications, until switched back to the builtin + model, and its name keeps working for writes (so a coefficient-only + write does not disturb the binding) until the last device unbinds. + See + include/linux/blk-iocost.h for the model interface. + When "model" is "linear", the following model parameters are defined. -- 2.43.0
