Canonical’s Balint Reczey recently proposed the implementation of LZ4 compression to Ubuntu’s initramfs (initial ramdisk) instead of the older gzip compression used in previous releases of the wildly used operating system. LZ4 is a lossless data compression algorithm that offers extremely fast compression and decompression speed.
During some initial tests on an old laptop, the developer reports that the initramfs extraction time decreased from approximately 1.2 seconds to about 0.24 seconds. The creation of the initramfs also received a speed boost of 2-3 seconds, decreasing from roughly 24 seconds to about 21 seconds, despite of slightly bigger initramfs files.
While Ubuntu 18.04 LTS (Bionic Beaver) will be the first to ship with the LZ4 compression option for the initramfs, it won’t be enabled by default. So you’ll have to manually enable it if you want your Ubuntu computer to boot a bit faster than usual. Canonical plans to enable it by default in Ubuntu 18.10, due for release in October 2018.
On the downside, it appears that the LZ4 compression algorithm makes slightly bigger initrd files, but the developer reports that this won’t affect future Ubuntu releases due to update-manager’s ability to remove old kernels to prevent the /boot directory from filling up with unwanted initramfs files and kernels.
Submitted by: Arnfried Walbrecht