Hi, Initramfs-tools uses gzip compression by default which served us well for quite some time but LZ4 offers way faster decompression while making a only slightly bigger initramfs files.
On my old laptop the initramfs extraction time decreased from ~1.2s to ~0.24s: (with lz4) kernel: [ 0.297726] Unpacking initramfs... kernel: [ 0.535061] Freeing initrd memory: 77940K kernel: [ 0.301637] Unpacking initramfs... kernel: [ 0.539109] Freeing initrd memory: 77940K (with gzip) kernel: [ 0.273748] Unpacking initramfs... kernel: [ 1.490066] Freeing initrd memory: 57140K kernel: [ 0.281729] Unpacking initramfs... kernel: [ 1.498493] Freeing initrd memory: 57140K The increase in the initrd.img size is ~14%: (lz4) -rw-r--r-- 1 root root 66709065 márc 19 14:24 /boot/initrd.img-4.15.0-12-generic (gzip) -rw-r--r-- 1 root root 58510993 márc 19 12:57 /boot/initrd.img-4.15.0-12-generic.bak Initramfs creation speed also improved a bit from ~24s to ~21s wall clock time: (lz4) update-initramfs: Generating /boot/initrd.img-4.15.0-12-generic 14.97user 6.31system 0:20.47elapsed 103%CPU (0avgtext+0avgdata 22368maxresident)k update-initramfs: Generating /boot/initrd.img-4.15.0-12-generic 15.18user 6.49system 0:20.48elapsed 105%CPU (0avgtext+0avgdata 22308maxresident)k (gzip) update-initramfs: Generating /boot/initrd.img-4.15.0-12-generic 18.23user 6.77system 0:23.61elapsed 105%CPU (0avgtext+0avgdata 22396maxresident)k update-initramfs: Generating /boot/initrd.img-4.15.0-12-generic 18.38user 6.83system 0:23.82elapsed 105%CPU (0avgtext+0avgdata 22292maxresident)k Base on the results I plan adding LZ4 compression support to initramfs-tools as requested in LP: #1488620 [1] in the next days without setting it as default and I propose setting LZ4 as default for 18.10. I'm aware of the old problem of /boot filling up with kernels and initramfs files but unattended-upgrades already removes old kernels [2] and update-manager is planned to do the same starting with 18.04 [3] thus Ubuntu systems will have enough space in /boot to allow slightly bigger initrd files. Cheers, Balint [1] https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/1488620 [2] https://launchpad.net/ubuntu/+source/unattended-upgrades/1.0ubuntu1 [3] https://code.launchpad.net/~rbalint/update-manager/remove-autoremovable-kernels/+merge/341599 -- ubuntu-devel mailing list ubuntu-devel@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel