[Bug 1958148] Re: mkinitramfs is too slow

[Launchpad Bug Tracker]

This bug was fixed in the package initramfs-tools - 0.140ubuntu13

---------------
initramfs-tools (0.140ubuntu13) jammy; urgency=medium

  * Lower the compression levels for zstd and lz4 (LP: #1958148)
    Following the discussion on the mailing list, we have reached
    a conclusion to lower the default compression levels:
    - For lz4, the compression level is lowered to 2 from 9
    - For zstd, the compression level is lowered to 1 from 19

 -- Julian Andres Klode <juliank at ubuntu.com>  Tue, 15 Mar 2022 16:00:55
+0100

** Changed in: initramfs-tools (Ubuntu)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1958148

Title:
  mkinitramfs is too slow

Status in initramfs-tools package in Ubuntu:
  Fix Released

Bug description:
  On the Nezha board creating an initrd takes more than 1 hour. The
  compression level -19 for zstd is unwisely chosen.

  Here are durations and compression results for an SiFive Unmatched
  board with four cores using zstd:

  -T0 -1 => 13.92s, 136298155 bytes
  -T0 -2 => 15.73s, 131717830 bytes
  -T0 -3 => 26.11s, 127434653 bytes
  -T0 -4 => 29.31s, 126924540 bytes
  -T0 -5 => 36.44s, 125296557 bytes
  -T0 -6 => 39.36s, 124781669 bytes
  -T0 -7 => 46.56s, 116200665 bytes
  -T0 -8 => 51.95s, 113172941 bytes
  -T0 -9 => 55.89s, 112835937 bytes
  -T0 -10 => 61.32s, 108326876 bytes
  -T0 -11 => 64.32s, 108115060 bytes
  -T0 -12 => 76.37s, 108016478 bytes
  -T0 -13 => 148.99s, 109121308 bytes
  -T0 -14 => 156.58s, 108908574 bytes
  -T0 -15 => 228.64s, 109213554 bytes
  -T0 -16 => 380.26s, 107260643 bytes
  -T0 -17 => 453.36s, 103679714 bytes
  -T0 -18 => 714.79s, 100402249 bytes
  -T0 -19 => 1046.58s, 100188713 bytes

  Compression level between -2 to -10 offer a good compromise between
  CPU time and compression results.

  Ideally there would be a parameter that we could pass to mkinitfs. But
  for as fast solution we should simply replace -19 by -9 in
  mkinitramfs.

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