Ubuntu
initramfs-tools package

  1. Bug #1932329
  2. Comment #0

Comment 0 for bug 1932329

Revision history for this message
Dimitri John Ledkov (xnox) wrote : Benchmark if we can compress kernel modules

Symbol: MODULE_COMPRESS_ZSTD [=n]
Type : bool

= Impacts to measure and observe =

== Disk space ==

* Inspect linux-modules-* and linux-modules-extra* deb package Installed-Size and Download-Size changes, i.e.

$ apt show linux-modules-5.8.0-53-generic linux-modules-extra-5.8.0-53-generic | grep -e Package: -e Size:

Package: linux-modules-5.8.0-53-generic
Installed-Size: 81.5 MB
Download-Size: 15.5 MB

Package: linux-modules-extra-5.8.0-53-generic
Installed-Size: 215 MB
Download-Size: 41.5 MB

In theory, there should not be a significant change in the Download-size. It is desired that there is a significant reduction in Installed-Size. Modules take up about 300MB and normally one has upto three kernel version installed, resulting in about of 1GB of disk space that one constantly pays for.

== Boot Speed ==

In theory, boot speed may either improve or regress. It depends if disk IO is slower than decompression speed, meaning loading compressed modules is faster.

Also one has to observe the changes in the initrd size. zstd(zstd) compression may result in slight growth, which shouldn't impact boot speed too much.

= Outcomes =

If installed size savings can be achieved without regressing bootspeed we should enable CONFIG_MODULE_COMPRESS_ZSTD=y by default.