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Set zstd as the default compression method for kdump initrd 

zstd has better compression ratio and time consumption balance.
When no customized compression method specified in kdump.conf,
we will use zstd as the default compression method.

**The test method:

I installed kexec-tools with and without the patch, executing the following
command for 4 times, and calculate the averange time:

$ rm -f /boot/initramfs-*kdump.img && time kdumpctl rebuild && \
  ls -ail /boot/initramfs-*kdump.img

**The test result:

Bare metal x86_64 machine:
        dracut with squash module
         zlib     lzo      xz       lz4        zstd
real     10.6282  11.0398  11.395   8.6424    10.1676
user      9.8932  11.9072  14.2304  2.8286     8.6468
sys       3.523    3.4626   3.6028  3.5        3.4942
size of
kdump.img 30575616 31419392 27102208 36666368 29236224

        dracut without squash module
        zlib      lzo      xz       lz4        zstd
real     9.509    19.4876  11.6724  9.0338    10.267
user    10.6028   14.516   17.8662  4.0476     9.0936
sys      2.942     2.9184   3.0662  2.9232     3.0662
size of
kdump.img 19247949 19958120 14505056 21112544 17007764

PowerVM hosted ppc64le VM:
        dracut with squash module | dracut without sqaush module
         zlib        zstd         |  zlib          zstd
real     10.6742     10.7572      |   9.7676       10.5722
user     18.754      19.8338      |  20.7932       13.179
sys       1.8358      1.864       |   1.637         1.663
                                  |
size of                           |
kdump.img 36917248   35467264     |  21441323      19007108

**discussion

zstd has a better compression ratio and time consumption balance.

v1 -> v2:
Use kdump_get_conf_val() to get dracut_args values of kdump.conf

v2 -> v3:
Attached testing benchmark

v3 -> v4:
Re-measured and re-attached the testing benchmark of x86_64 and ppc64le.
Changed regex '.*[[:space:]]' to '(^|[[:space:]])'

v4 -> v5:
Attacked lzo/xz/lz4 testing benchmark.

v5 -> v6:
Add zstd as required in kexec-tools.spec

Hello Coiby, you may use "RELEASE=34 make test-run", for
CONFIG_RD_ZSTD is enabled since fc-cloud-34

Acked-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Tao Liu <ltao@redhat.com>
This commit is contained in:
Tao Liu 2022-01-05 17:42:12 +08:00 committed by Coiby Xu
parent 0e162120b6
commit 0311f6e25b
4 changed files with 15 additions and 0 deletions
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6
kdump-lib.sh
View File

@ -443,6 +443,12 @@ is_wdt_active()
return 1
}
have_compression_in_dracut_args()
{
[[ "$(kdump_get_conf_val dracut_args)" =~ \
(^|[[:space:]])--(gzip|bzip2|lzma|xz|lzo|lz4|zstd|no-compress|compress)([[:space:]]|$) ]]
}
# If "dracut_args" contains "--mount" information, use it
# directly without any check(users are expected to ensure
# its correctness).

1
kexec-tools.spec
View File

@ -70,6 +70,7 @@ Requires: dracut >= 050
Requires: dracut-network >= 050
Requires: dracut-squash >= 050
Requires: ethtool
Requires: zstd
Recommends: grubby
BuildRequires: make
BuildRequires: zlib-devel elfutils-devel glib2-devel bzip2-devel ncurses-devel bison flex lzo-devel snappy-devel libzstd-devel

4
mkdumprd
View File

@ -431,6 +431,10 @@ done <<< "$(kdump_read_conf)"
handle_default_dump_target
if ! have_compression_in_dracut_args; then
add_dracut_arg "--compress" "zstd"
fi
if [[ -n $extra_modules ]]; then
add_dracut_arg "--add-drivers" "$extra_modules"
fi

4
mkfadumprd
View File

@ -62,6 +62,10 @@ if is_squash_available; then
_dracut_isolate_args+=(--add squash)
fi
if ! have_compression_in_dracut_args; then
_dracut_isolate_args+=(--compress zstd)
fi
if ! dracut --force --quiet "${_dracut_isolate_args[@]}" "$@" "$TARGET_INITRD"; then
perror_exit "mkfadumprd: failed to setup '$TARGET_INITRD' with dump capture capability"
fi