If available, use 'zstd' compression method to optimize the size of
the initrd built with fadump support. Also, 'squash+zstd' is not
preferred because more disk space is consumed with 'squash+zstd' due
to the additional binaries needed for fadump with squash case.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Tao Liu <ltao@redhat.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>
With commit fa9201b2 ("fadump: isolate fadump initramfs image within
the default one"), initramfs image gets to hold two images, one for
production kernel boot purpose and the other for capture kernel boot.
Most files are common among the two images. Retain file modification
time to replace duplicate files with hardlinks and save space. Also,
avoid unnecessarily compressing fadump image that is decompressed
immediately anyway.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>
With commit fa9201b2 ("fadump: isolate fadump initramfs image within
the default one"), initramfs image gets to hold two squash images, one
for production kernel boot purpose and the other for capture kernel
boot. Having separate images improved reliability for both production
kernel and capture kernel boot scenarios, but the size of initramfs
image became considerably larger.
Instead of having squash images, compressing $initdir without using
squash images reduced the size of initramfs image for fadump case by
around 30%. So, avoid using squash for fadump case.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>
Previously kexec-tools will pass "--compress zstd" to dracut. It
will make dracut to decide whether: a) call mksquashfs to make a
zstd format squash-root.img, b) call cmd zstd to make a initramfs.
Since dracut(>= 057) has decoupled the compressor for dracut and
dracut-squash, So in this patch, we will pass the compressor seperately.
Note:
The is_squash_available && !dracut_has_option --squash-compressor
&& !is_zsdt_command_available case is left unprocessed on purpose.
Actually, the situation when we want to call zstd compression is:
1) If squash function OK, we want dracut to invoke mksquashfs to make
a zstd format squash-root.img within initramfs.
2) If squash function is not OK, and cmd zstd presents, we want dracut
to invoke cmd zstd to make a zstd format initramfs.
is_zstd_command_available check can handle case 2 completely.
However, for the is_squash_available check, it cannot handle case 1
completely. It only checks if the kernel supports squashfs, it doesn't
check whether the squash module has been added by dracut when making
initramfs. In fact, in kexec-tools we are unable to do the check,
there are multiple ways to forbit dracut to load a module, such as
"dracut -o module" and "omit_dracutmodules in dracut.conf".
When squash dracut module is omitted, is_squash_available check will
still pass, so "--compress zstd" will be appended to dracut cmdline,
and it will call cmd zstd to do the compression. However cmd zstd may
not exist, so it fails.
The previous "--compress zstd" is ambiguous, after the intro of
"--squash-compressor", "--squash-compressor" only effect for
mksquashfs and "--compress" only effect for specific cmd.
So for the is_squash_available && !dracut_has_option
--squash-compressor && !is_zsdt_command_available case, we just leave
it to be handled the default way.
Reviewed-by: Philipp Rudo <prudo@redhat.com>
Signed-off-by: Tao Liu <ltao@redhat.com>
This patch will make zstd as recommended instead of required for
kexec-tools. If zstd command/package is unavaliable, it can failback to invoke
gzip when making kdump initramfs.
Fixes: 0311f6e ("Set zstd as the default compression method for kdump initrd")
Signed-off-by: Tao Liu <ltao@redhat.com>
Acked-by: Coiby Xu <coxu@redhat.com>
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 is a batch update done with:
shfmt -s -w mkfadumprd mkdumprd kdumpctl *-module-setup.sh
Clean up code style and reduce code base size, no behaviour change.
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Philipp Rudo <prudo@redhat.com>
Declare and assign separately to avoid masking return values:
https://github.com/koalaman/shellcheck/wiki/SC2155
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Philipp Rudo <prudo@redhat.com>
kdumpctl, mkdumprd, *-module-setup.sh only target bash, since they
only run in first kernel and depend on dracut, and dracut depends
on bash. So use '[[ ]]' to replace '[ ]'.
This is a batch update done with following command:
`sed -i -e 's/\(\s\)\[\s\([^]]*\)\s\]/\1\[\[\ \2 \]\]/g' kdumpctl, mkdumprd, *-module-setup.sh`
and replaced [ ... -a ... ] with [[ ... ]] && [[ ... ]] manually.
See https://tldp.org/LDP/abs/html/testconstructs.html for more details
on '[[ ]]', it's more versatile, safer, and slightly faster than '[ ]'.
This will also help shfmt to clean up the code in later commits.
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Philipp Rudo <prudo@redhat.com>
To make arguments list work as expected, array is preferred.
Check following link for details:
https://github.com/koalaman/shellcheck/wiki/SC2089
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Philipp Rudo <prudo@redhat.com>
After fadump embedded the fadump initramfs in the normal initramfs,
kdumpctl will mistakenly rebuild the initramfs everytime.
kdumpctl checks the hostonly-kernel-modules.txt file in initramfs
to check if required drivers are included, but the normal initramfs
is built in non-hostonly mode, so it doesn't have a
hostonly-kernel-modules.txt file. The check will always fail.
So let mkfadumprd make a copy of the hostonly-kernel-modules.txt in the
fadump initramfs and let kdumpctl check that file instead.
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
In case of fadump, the initramfs image has to be built to boot into
the production environment as well as to offload the active crash dump
to the specified dump target (for boot after crash). As the same image
would be used for both boot scenarios, it could not be built optimally
while accommodating both cases.
Use --include to include the initramfs image built for offloading
active crash dump to the specified dump target. Also, introduce a new
out-of-tree dracut module (99zz-fadumpinit) that installs a customized
init program while moving the default /init to /init.dracut. This
customized init program is leveraged to isolate fadump image within
the default initramfs image by kicking off default boot process
(exec /init.dracut) for regular boot scenario and activating fadump
initramfs image, if the system is booting after a crash.
If squash is available, ensure default initramfs image is also built
with squash module to reduce memory consumption in capture kernel.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Kairui Song <kasong@redhat.com>
