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powerpc: Set nr_cpus=16 for kdump kernel #97

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powerpc: Set nr_cpus=16 for kdump kernel #97

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0186557
powerpc: consider CPU count while calculating crashkernel value
sourabhjains Aug 23, 2025
3fca334
powerpc: Set nr_cpus=16 for kdump kernel
sourabhjains Aug 23, 2025
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2 changes: 1 addition & 1 deletion gen-kdump-sysconfig.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,7 @@ ppc64le)
update_param KDUMP_COMMANDLINE_REMOVE \
"hugepages hugepagesz slub_debug quiet log_buf_len swiotlb hugetlb_cma ignition.firstboot"
update_param KDUMP_COMMANDLINE_APPEND \
"irqpoll nr_cpus=1 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd hugetlb_cma=0 kfence.sample_interval=0"
"irqpoll nr_cpus=16 noirqdistrib reset_devices cgroup_disable=memory numa=off udev.children-max=2 ehea.use_mcs=0 panic=10 kvm_cma_resv_ratio=0 transparent_hugepage=never novmcoredd hugetlb_cma=0 kfence.sample_interval=0"
update_param FADUMP_COMMANDLINE_APPEND \
"nr_cpus=16 numa=off cgroup_disable=memory cma=0 kvm_cma_resv_ratio=0 hugetlb_cma=0 transparent_hugepage=never novmcoredd udev.children-max=2"
;;
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26 changes: 26 additions & 0 deletions kdump-lib.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -975,6 +975,24 @@ _crashkernel_add()
echo "${ret%,}"
}


find_nr_cpus()
{
local _cmdline_append
local _nr_cpus

# shellcheck disable=SC2153
if [[ $DEFAULT_DUMP_MODE == "fadump" ]]; then
_cmdline_append="$FADUMP_COMMANDLINE_APPEND"
else
_cmdline_append="$KDUMP_COMMANDLINE_APPEND"
fi
_nr_cpus=$(echo "$_cmdline_append" | sed -n 's/.*nr_cpus=\([0-9]\+\).*/\1/p')
ddebug "Configured nr_cpus=$_nr_cpus"
echo "$_nr_cpus"
}


# get default crashkernel
# $1 dump mode, if not specified, dump_mode will be judged by is_fadump_capable
# $2 kernel-release, if not specified, got by _get_kdump_kernel_version
Expand Down Expand Up @@ -1025,6 +1043,14 @@ kdump_get_arch_recommend_crashkernel()
has_mlx5 && ((_delta += 150))
fi
elif [[ $_arch == "ppc64le" ]]; then
local _per_cpu_area
local _nr_cpus

# 1MB per CPU
_per_cpu_area=1
_nr_cpus=$(find_nr_cpus)

_delta=$(( _delta + _per_cpu_area * _nr_cpus ))
if [[ $_dump_mode == "fadump" ]]; then
_ck_cmdline="4G-16G:768M,16G-64G:1G,64G-128G:2G,128G-1T:4G,1T-2T:6G,2T-4T:12G,4T-8T:20G,8T-16T:36G,16T-32T:64G,32T-64T:128G,64T-:180G"
else
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