Public bug reported:
Since 23.10 the initrd consists of 4 embedded cpio:
- amd microcode
- intel microcode
- firmware + kernel modules
- rest (compressed)
Previously it was:
- amd microcode
- intel microcode
- rest (compressed)
There is no archive size header for cpio, so unmkinitramfs has to parse
headers of each entry in uncompressed archives.
> time unmkinitramfs 23.04/{initrd,unpack}
real 0m3.625s
user 0m1.595s
sys 0m3.467s
> time unmkinitramfs 23.10/{initrd,unpack}
real 0m15.982s
user 0m20.174s
sys 0m6.995s
> for dir in 23.04/unpack/early*; do printf '%-20s %s\n' "$dir" "$(find "$dir"
> | wc -l)"; done
23.04/unpack/early 5
23.04/unpack/early2 6
> for dir in 23.10/unpack/early*; do printf '%-20s %s\n' "$dir" "$(find "$dir"
> | wc -l)"; done
23.10/unpack/early 5
23.10/unpack/early2 6
23.10/unpack/early3 2874
Here https://github.com/slowpeek/unmkinitramfs-turbo I've made it a lot faster
with two changes:
- bash instead of sh for bash's "read -N"
- xxd dump of initrd instead of raw binary data
I wonder, if the developers are interested in accepting my improvements into
the code base?
> time unmkinitramfs-classic-turbo 23.10/{initrd,unpack}
real 0m2.209s
user 0m2.161s
sys 0m1.341s
> time unmkinitramfs-turbo 23.10/{initrd,unpack}
early .. +
early2 .. +
early3 .. +
main .. +
real 0m1.973s
user 0m2.094s
sys 0m1.244s
All tools in the repo, even the classic one, feature -s/--scan option. With it,
the tools only dump offset + size for embedded archives, nothing is unpacked.
It can be used to measure parsing speed.
In the repo there are three tools:
- unmkinitramfs-classic: the original tool
- unmkinitramfs-classic-turbo: the improved tool with minimal changes
- unmkinitramfs-turbo: the improved tool with many changes to my tastes, extra
dependency on "file" and some additional features (-ss option, decompression
with 7za)
** Affects: initramfs-tools (Ubuntu)
Importance: Undecided
Status: New
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2059976
Title:
unmkinitramfs is very slow on initrd from ubuntu 23.10+, solution
proposed
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/2059976/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
