10-build-initramfs: xz --threads=0 doesn't use more than one thread at -8 #48
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Finally managed to care of this, thanks! |
clexanis
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Dec 12, 2022
Quoting from the bug report:
| How many threads are used also depends on the compression level. At -6,
| I've seen it use 3-4 threads, which speeds up initramfs compression a lot.
| With -8, it always only uses one thread (although maybe it also depends on
| the amount of data being compressed; I don't know).
The default compression preset level is -6, so there's no need to specify
it.
This also matches the behavior of initramfs-tools >=0.119:
| commit cf9691da3847a6bfadb4a5c9e0f6213bd7d10fdc
| Author: Ben Hutchings <ben@decadent.org.uk>
| Date: Thu Oct 16 15:34:54 2014 +0200
|
| mkinitramfs: Use default xz compression level rather than -8
|
| xz -8 wants 370 MB VM for compression, but Debian tries to support
| systems with less physical memory than that.
|
| The benchmark results given in commit bedf1e3c0882 ('Use -8 for
| compression with xz.') show only a 1% increase in size when changing
| to -6, but VM usage will be reduced by 75%.
|
| Closes: #697335
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
| diff --git mkinitramfs mkinitramfs
| index 07190ed..25932c1 100755
| --- mkinitramfs
| +++ mkinitramfs
| @@ -146,7 +146,7 @@ if dpkg --compare-versions "${version}" lt "2.6.38" 2>/dev/null; then
| fi
|
| [ "${compress}" = lzop ] && compress="lzop -9"
| -[ "${compress}" = xz ] && compress="xz -8 --check=crc32"
| +[ "${compress}" = xz ] && compress="xz --check=crc32"
|
| if [ -d "${outfile}" ]; then
| echo "${outfile} is a directory" >&2
Let's keep the xz wrapper though, to force its usage independent of the
initramfs-tools version being used and have it available, if we decide to
add further custom options in the future.
Thanks: Dr. András Korn
Closes: grml#48
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How many threads are used also depends on the compression level. At -6, I've seen it use 3-4 threads, which speeds up initramfs compression a lot. With -8, it always only uses one thread (although maybe it also depends on the amount of data being compressed; I don't know).
I suggest that the -8 in /etc/grml/fai/config/files/etc/initramfs-tools/conf.d/xz-compress/GRMLBASE be replaced with -6.
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