Function backend_delivers_preemption_timer 

pub fn backend_delivers_preemption_timer(backend: Backend) -> bool

Whether backend’s runtime arms a PMU preemption timer and delivers its events, so --max-timeslice really preempts a thread that makes no syscall: the backend’s stated delivers_preemption_timer_events. ptrace (and e9patch preprocessing, which runs on it) and KVM do. SaBRe accepts a timer request and delivers nothing; DBT and in-guest LiteInst refuse it.