Function account_chunk 

fn account_chunk<C: Columnar>(
    entry: &PagedColumn<C>,
) -> (usize, usize, usize, usize)

Resident-only accounting. Returns (records, size_bytes, capacity_bytes, allocations) for a single chain entry; paged-out entries contribute 0 across the board.

BatcherEvent feeds the mz_arrangement_batcher_*_raw introspection tables, which downstream surface as memory-resource dashboards. Bytes living on swap or in a pager file aren’t part of RSS and shouldn’t be reported there.