New Linux tech compresses memory in RAM, as RAM, for 452x speedup
a day ago
- CRAM is a new Linux memory compression model from Meta that keeps compressed data in RAM instead of using swap.
- It offers up to 452x faster read performance compared to ZRAM by using standard memory semantics and a private NUMA node.
- The largest performance hit in compressed memory comes from swap behavior and page faults, not compression itself.
- CRAM uses a 'Chicken Bit' to prevent cascading failures when writes exceed allocation capacity.
- With write operations, CRAM still achieves up to 5.4x speedup over ZRAM, though performance drops due to page faults and folio migration.
- The method is still under development, with open problems in managing logical RAM size and allocation pressure.
- CRAM is designed for large Linux servers but could benefit systems like the Steam Deck if integrated into the kernel.