GoKawiil
Tech News
At the Linux Plumbers Conference in Prague, Meta engineer Gregory Price presented CRAM, a hardware-offloaded memory compression technique for Linux that allows cacheline and byte-level access to compressed data. Unlike ZRAM or Zswap, CRAM represents compressed memory as a private NUMA node rather than a block device, letting the kernel manage it using standard memory semantics like migration and ballooning.
Gregory Price and a team at Meta have built CRAM, a new Linux memory-compression technique that keeps compressed data directly in RAM instead of routing it through the swap layer like existing tools zswap and ZRAM. CRAM uses a private NUMA node to let Linux manage compressed memory with its normal memory semantics, including migration and ballooning, and includes a mechanism called the 'Chicken Bit' to pause CRAM during allocation management. Early benchmarks cited show read performance gains of up to 452 times over ZRAM.
A blog post walks through configuring swap on NixOS for desktops and laptops that use suspend-then-hibernate, contrasting swap partitions with swap files. It notes that swap files complicate hibernation because initramfs must locate the swap space before file systems mount, requiring an EFI variable to record the location at hibernation time. The author shares working configurations: a simple swap partition on a desktop, and a LUKS-encrypted btrfs swap file on a laptop using the disko luks-btrfs-subvolumes template.