3:24 a.m.
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:
Attached lzo/xz/lz4 testing benchmark.
Signed-off-by: Tao Liu <ltao(a)redhat.com>
---
kdump-lib.sh | 6 ++++++
mkdumprd | 4 ++++
mkfadumprd | 4 ++++
3 files changed, 14 insertions(+)
diff --git a/kdump-lib.sh b/kdump-lib.sh
index e435498..6d668a5 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -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).
diff --git a/mkdumprd b/mkdumprd
index d87d588..9c26ecc 100644
--- a/mkdumprd
+++ b/mkdumprd
@@ -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
diff --git a/mkfadumprd b/mkfadumprd
index b890f83..16fdacc 100644
--- a/mkfadumprd
+++ b/mkfadumprd
@@ -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
--
2.33.1