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powerpc: Set nr_cpus=16 for kdump kernel

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Resolves: https://issues.redhat.com/browse/RHEL-77215
Upstream: kdump-utils
Conflict: manually apply

commit 4f7970eefa6cba5d7cebd739718fb947a3fedbad (HEAD -> main, origin/main, origin/HEAD)
Author: Sourabh Jain <sourabhjain@linux.ibm.com>
Date:   Thu Dec 4 13:51:21 2025 +0530

    powerpc: Set nr_cpus=16 for kdump kernel

    Configure the kdump kernel with nr_cpus=16 to enable multi-threading in
    the makedumpfile core collector, allowing faster dump collection.

    Commit d428557fc2b59 ("Use all available CPUs to collect dump")
    introduced multi-threading support in the core collector.

    There are two reasons for choosing nr_cpus=16:

     - Multiple experiments show that optimal performance is achieved when
       nr_cpus is between 16 and 30. The graph in commit d428557fc2b59
       supports this.

     - nr_cpus=16 is already used for the fadump kernel, so using the same
       value for kdump to maintain consistency.

    Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>

Since there is no gen-kdump-sysconfig.sh in RHEL-9 kexec-tools, and the
patch just change the nr_cpus from 1 to 16, so apply it manually.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
This commit is contained in:
Pingfan Liu 2025-12-19 18:42:18 +08:00
parent 1b53bbd448
commit bba7f4d4d0
1 changed files with 1 additions and 1 deletions
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2
kdump.sysconfig.ppc64le
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@ -21,7 +21,7 @@ KDUMP_COMMANDLINE_REMOVE="hugepages hugepagesz slub_debug quiet log_buf_len swio
# This variable lets us append arguments to the current kdump commandline
# after processed by KDUMP_COMMANDLINE_REMOVE
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"
KDUMP_COMMANDLINE_APPEND="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"
# This variable lets us append arguments to fadump (powerpc) capture kernel,
# further to the parameters passed via the bootloader.