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| author | Hui Wang <john.wanghui@huawei.com> | 2018-11-07 10:36:43 +0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-12-18 13:38:37 +0100 |
| commit | aa02ef099cff042c2a9109782ec2bf1bffc955d4 (patch) | |
| tree | 1ad972b32252d59b259d75652bfc8c8e7e339789 /arch/x86/kernel/smpboot.c | |
| parent | 438cbf8871246606f2fc1964d301fa02af39e4e4 (diff) | |
| download | linux-aa02ef099cff042c2a9109782ec2bf1bffc955d4.tar.gz linux-aa02ef099cff042c2a9109782ec2bf1bffc955d4.tar.bz2 linux-aa02ef099cff042c2a9109782ec2bf1bffc955d4.zip | |
x86/topology: Use total_cpus for max logical packages calculation
nr_cpu_ids can be limited on the command line via nr_cpus=. This can break the
logical package management because it results in a smaller number of packages
while in kdump kernel.
Check below case:
There is a two sockets system, each socket has 8 cores, which has 16 logical
cpus while HT was turn on.
0 1 2 3 4 5 6 7 | 16 17 18 19 20 21 22 23
cores on socket 0 threads on socket 0
8 9 10 11 12 13 14 15 | 24 25 26 27 28 29 30 31
cores on socket 1 threads on socket 1
While starting the kdump kernel with command line option nr_cpus=16 panic
was triggered on one of the cpus 24-31 eg. 26, then online cpu will be
1-15, 26(cpu 0 was disabled in kdump), ncpus will be 16 and
__max_logical_packages will be 1, but actually two packages were booted on.
This issue can reproduced by set kdump option nr_cpus=<real physical core
numbers>, and then trigger panic on last socket's thread, for example:
taskset -c 26 echo c > /proc/sysrq-trigger
Use total_cpus which will not be limited by nr_cpus command line to calculate
the value of __max_logical_packages.
Signed-off-by: Hui Wang <john.wanghui@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <guijianfeng@huawei.com>
Cc: <wencongyang2@huawei.com>
Cc: <douliyang1@huawei.com>
Cc: <qiaonuohan@huawei.com>
Link: https://lkml.kernel.org/r/20181107023643.22174-1-john.wanghui@huawei.com
Diffstat (limited to 'arch/x86/kernel/smpboot.c')
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index a9134d1910b9..ccd1f2a8e557 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1347,7 +1347,7 @@ void __init calculate_max_logical_packages(void) * extrapolate the boot cpu's data to all packages. */ ncpus = cpu_data(0).booted_cores * topology_max_smt_threads(); - __max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus); + __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus); pr_info("Max logical packages: %u\n", __max_logical_packages); } |