Add a rough esitimation support, currently, following memory usage are
checked by this sub command:
- System RAM
- Kdump Initramfs size
- Kdump Kernel image size
- Kdump Kernel module size
- Kdump userspace user and other runtime allocated memory (currently
simply using a fixed value: 64M)
This will provide user three values as reference,
The output of kdumpctl estimate looks like this:
# kdumpctl estimate
Reserved crashkernel: 128M
Baseline crashkernel: 160M
Estimated crashkernel: 143M
Recommanded crashkernel: 160M
Kenrel image size: 47M
Kernel modules size: 9M
Initramfs size: 22M
Runtime reservation: 64M
Large modules:
nouveau: 2281472
xfs: 1515520
WARNING: Current crashkernel size is lower than recommanded size 160M.
"Reserved crashkernel" is currently reserved crashkernel value.
"Baseline crashkernel" is the crashkernel size when `crashkernel=auto`
is used, based on crashkernel auto rules from RHEL.
"Estimated crashkernel" is the estimate value based on the memory usage
items listed above.
"Recommanded crashkernel" will use the largest value of estimated
crashkernel and the baseline crashkernel.
All values are rounded up and converted to MB.
All modules with static size larger than 1M will be listed as large
module.
Signed-off-by: Kairui Song <kasong(a)redhat.com>
---
kdump-lib.sh | 69 ++++++++++++++++++++++++++++++++++++++++
kdumpctl | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 156 insertions(+), 2 deletions(-)
diff --git a/kdump-lib.sh b/kdump-lib.sh
index e87b9f1..9d89598 100755
--- a/kdump-lib.sh
+++ b/kdump-lib.sh
@@ -891,3 +891,72 @@ kdump_get_arch_recommend_size()
echo $result
return 0
}
+
+check_vmlinux()
+{
+ # Use readelf to check if it's a valid ELF
+ # TODO: find a better to way to check that it's really vmlinux
+ # and not just an elf
+ readelf -h $1 &>/dev/null || return 1
+}
+
+get_vmlinux_size()
+{
+ local size=0
+
+ while read _type _offset _virtaddr _physaddr _fsize _msize _flg _aln; do
+ size=$(( $size + $_msize ))
+ done <<< $(readelf -l -W $1 | grep "^ LOAD" 2>/dev/stderr)
+
+ echo $size
+}
+
+try_decompress()
+{
+ # The obscure use of the "tr" filter is to work around older versions of
+ # "grep" that report the byte offset of the line instead of the pattern.
+
+ # Try to find the header ($1) and decompress from here
+ for pos in `tr "$1\n$2" "\n$2=" < "$4" | grep -abo
"^$2"`
+ do
+ if ! type -P $3 > /dev/null; then
+ ddebug "Signiature detected but '$3' is missing, skip this
decompressor"
+ break
+ fi
+
+ pos=${pos%%:*}
+ tail -c+$pos "$img" | $3 > $5 2> /dev/null
+ if check_vmlinux $5; then
+ ddebug "Kernel is extracted with '$3'"
+ return 0
+ fi
+ done
+
+ return 1
+}
+
+# Borrowed from linux/scripts/extract-vmlinux
+get_kernel_size()
+{
+ # Prepare temp files:
+ local img=$1 tmp=$(mktemp /tmp/vmlinux-XXX)
+ trap "rm -f $tmp" 0
+
+ # Try to check if it's a vmlinux already
+ check_vmlinux $img && get_vmlinux_size $img && return 0
+
+ # That didn't work, so retry after decompression.
+ try_decompress '\037\213\010' xy gunzip $img $tmp || \
+ try_decompress '\3757zXZ\000' abcde unxz $img $tmp || \
+ try_decompress 'BZh' xy bunzip2 $img $tmp || \
+ try_decompress '\135\0\0\0' xxx unlzma $img $tmp || \
+ try_decompress '\211\114\132' xy 'lzop -d' $img $tmp || \
+ try_decompress '\002!L\030' xxx 'lz4 -d' $img $tmp || \
+ try_decompress '(\265/\375' xxx unzstd $img $tmp
+
+ # Finally check for uncompressed images or objects:
+ get_vmlinux_size $tmp && return 0
+
+ derror "Failed to get kernel image size"
+ return 1
+}
diff --git a/kdumpctl b/kdumpctl
index 24f5cf7..04b38d1 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -1214,6 +1214,88 @@ rebuild() {
return $?
}
+do_estimate() {
+ local kdump_mods
+ local -A large_mods
+ local baseline
+ local kernel_size mod_size initrd_size baseline_size runtime_size reserved_size
estimated_size recommanded_size
+ local size_mb=$(( 1024 * 1024 ))
+
+ setup_initrd
+
+ if [ ! -f $TARGET_INITRD ]; then
+ derror "kdumpctl estimate: kdump initramfs is not built yet."
+ exit 1
+ fi
+
+ kdump_mods="$(lsinitrd $TARGET_INITRD -f
/usr/lib/dracut/hostonly-kernel-modules.txt | tr '\n' ' ')"
+
+ baseline=$(kdump_get_arch_recommend_size)
+ if [[ "${baseline: -1}" == "M" ]]; then
+ baseline=${baseline%M}
+ elif [[ "${baseline: -1}" == "G" ]]; then
+ baseline=$(( ${baseline%G} * 1024 ))
+ elif [[ "${baseline: -1}" == "T" ]]; then
+ baseline=$(( ${baseline%Y} * 1048576 ))
+ fi
+
+ # The default value when using crashkernel=auto
+ baseline_size=$(( $baseline * $size_mb ))
+ # Current reserved crashkernel size
+ reserved_size=$(cat /sys/kernel/kexec_crash_size)
+ # A pre-estimated value for userspace usage and kernel
+ # runtime allocation, 64M should good for most cases
+ runtime_size=$(( 64 * $size_mb ))
+ # Kernel image size
+ kernel_size=$(get_kernel_size $KDUMP_KERNEL)
+ # Kdump initramfs size
+ initrd_size=$(du -b $TARGET_INITRD | awk '{print $1}')
+ # Kernel modules size after loaded
+ mod_size=0
+ while read _name _size _; do
+ if [[ ! " $kdump_mods " == *" $_name "* ]]; then
+ continue
+ fi
+ mod_size=$(( $mod_size + $_size ))
+
+ # Mark module with static size larger than 2M as large module
+ if [[ $(( $_size / $size_mb )) -ge 1 ]]; then
+ large_mods[$_name]=$_size
+ fi
+ done <<< $(< /proc/modules)
+
+ estimated_size=$(( $kernel_size + $mod_size + $initrd_size + $runtime_size ))
+
+ if [[ $baseline_size -gt $estimated_size ]]; then
+ recommanded_size=$baseline_size
+ else
+ recommanded_size=$estimated_size
+ fi
+
+ echo "Reserved crashkernel: $(( ( $reserved_size + $size_mb - 1 ) / $size_mb
))M"
+ echo "Baseline crashkernel: $(( ( $baseline_size + $size_mb - 1 ) / $size_mb
))M"
+ echo "Estimated crashkernel: $(( ( $estimated_size + $size_mb - 1 ) / $size_mb
))M"
+ echo "Recommanded crashkernel: $(( ( $recommanded_size + $size_mb - 1 ) / $size_mb
))M"
+ echo
+ echo "Kenrel image size: $(( ( $kernel_size + $size_mb - 1 ) / $size_mb
))M"
+ echo "Kernel modules size: $(( ( $mod_size + $size_mb - 1 ) / $size_mb ))M"
+ echo "Initramfs size: $(( ( $initrd_size + $size_mb - 1 ) / $size_mb
))M"
+ echo "Runtime reservation: $(( ( $runtime_size + $size_mb - 1 ) / $size_mb
))M"
+ echo -n "Large modules:"
+ if [[ "${#large_mods[@]}" -eq 0 ]]; then
+ echo " <none>"
+ else
+ echo ""
+ for _mod in ${!large_mods[@]}; do
+ echo " $_mod: ${large_mods[$_mod]}"
+ done
+ fi
+
+ if [[ $reserved_size -le $recommanded_size ]]; then
+ echo "WARNING: Current crashkernel size is lower than recommanded size $(( (
$recommanded_size + 1023 ) / $size_mb ))M."
+ fi
+}
+
if [ ! -f "$KDUMP_CONFIG_FILE" ]; then
derror "Error: No kdump config file found!"
exit 1
@@ -1269,8 +1351,11 @@ main ()
showmem)
show_reserved_mem
;;
+ estimate)
+ do_estimate $2
+ ;;
*)
- dinfo $"Usage: $0
{start|stop|status|restart|reload|rebuild|propagate|showmem}"
+ dinfo $"Usage: $0
{start|stop|status|restart|reload|rebuild|propagate|showmem|estimate}"
exit 1
esac
}
@@ -1280,6 +1365,6 @@ single_instance_lock
# To avoid fd 9 leaking, we invoke a subshell, close fd 9 and call main.
# So that fd isn't leaking when main is invoking a subshell.
-(exec 9<&-; main $1)
+(exec 9<&-; main $@)
exit $?
--
2.29.2
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