Function arena_usage 

pub(crate) fn arena_usage(
    skel: &BpfSkel<'_>,
    counted: bool,
) -> (Option<u64>, u64)

What the arena holds, in bytes, and the size of the map. Kernels from 7.3 account the allocated pages in the map’s memlock; before that the figure is the one kept at the allocator by eevdf_arena_alloc_pages(), when @counted says those programs are attached, and None otherwise.