Gives stats about system IO usage.
type t
include sig ... end
val t_of_sexp : Base.Sexp.t ‑> t
val sexp_of_t : t ‑> Base.Sexp.t
val create : unit ‑> t
val update : t ‑> kind:Fd.Kind.t ‑> bytes:Core.Int63.t ‑> unit
val total : t ‑> Core.Int63.t
val get : t ‑> kind:Fd.Kind.t ‑> Core.Int63.t