pub const ALLOCATION: u64 = 16;Expand description
What the allocator takes on top of a block, for every block handed out.
Every general purpose allocator keeps a header beside the block and rounds the size up to an alignment, and none of them will say by how much. Sixteen is glibc’s, an eight byte header and a sixteen byte alignment, and it is a floor rather than an average, so a caller that adds this per allocation is still under reporting and is under reporting by much less than one that adds nothing.
It matters because the things this budget counts are made of small allocations. A hash table of seventeen million groups is seventeen million blocks, and sixteen bytes apiece is a quarter of a gigabyte that was invisible before #227.