Function mi_unsafe_heap_page_is_under_utilized 

pub unsafe extern "C" fn mi_unsafe_heap_page_is_under_utilized(
    heap: *mut mi_heap_t,
    p: *mut c_void,
    perc_threshold: usize,
) -> bool

Check if the heap page containing p is under-utilized.

Safety

Assumes the page belonging to p is only accessed by the calling thread.