Hi On Tue, Feb 1, 2022 at 6:54 AM Tobias Powalowski via arch-dev-public < arch-dev-public@lists.archlinux.org> wrote:
> Hi guys, > did some initcpio optimizing lately and implemented correct symlink > handling. This saves already some space. > https://bugs.archlinux.org/task/73439 > > Now one major problem left in recent initcpio, uncompressed modules: > https://github.com/archlinux/mkinitcpio/pull/25 > https://bugs.archlinux.org/task/72882 > At the moment modules are uncompressed during initcpio creation. This leads > to bigger RAM usage during boot, makes it a bit smaller on storage, due to > not recompress compressed modules. On small initrds for normal boot this is > not a big matter. > > My measurement with all patches added: > Ramdisk size uncompressed modules: 13261677 > Ramdisk size compressed modules: 13112083 > (Note the compressed one is smaller due to the symlink patches added) > Unpacked initramfs uncompressed modules: 35 MB > Unpacked initramfs compressed modules: 26 MB > This memory usage difference does not make much difference for the boot experience. Keep in mind that it is initramfs stage and all the memory used here (except a tiny part) is reclaimed/freed at the end of initramfs. So this memory difference is just a blip at the first 100ms of the boot process when no OS/services are loaded and no memory pressure exists. The drawback of this solution is that kernel modules are double-compressed - the first time with initramfs and then module compression itself. And decompressing requires extra time that is probably more valuable at initramfs stage. What is the reported systemd-analyze time for compressed vs non-compressed versions? > Using this on the biggest "initramfs testsuite" archboot shows the most > advantages. > > If you like to test it on your own initramfs setup you can use: > > https://gitlab.archlinux.org/tpowa/archboot/-/blob/master/usr/share/archboot/patches/31-initcpio.functions.fixed > for /usr/lib/initcpio/functions and recreate your initramdisk. > > Now my question to the list, what should be the default how arch handles > modules in initramfs? > - Shall we leave the modules at compression level used during kernel build? > --> This means the uncompression should be optional. > - Shall we still uncompress the modules always? (Status now) > --> Then using modules as is needs to be optional. > > Thanks for you input. > greetings > tpowa > -- > Tobias Powalowski > Archlinux Developer & Package Maintainer (tpowa) > https://www.archlinux.org <http://www.archlinux.org> > tp...@archlinux.org > > St. Martin-Apotheke > Herzog-Georg-Str. 25 > 89415 Lauingen > https://www.st-martin-apo.de > i...@st-martin-apo.de >
