Expand description
Chunk buffer recycling.
A 100 GB transfer at 1 MiB chunks is 100k chunks, each needing a plaintext
buffer and an output buffer. Allocating and freeing 200k multi-megabyte
buffers hands the allocator a workload it will happily serve and then return
to the OS, so the process spends its time in madvise/page faults instead of
moving bytes. Recycling keeps a small fixed set of hot buffers instead.