lscpu may show the wrong number of physical sockets on aarch64 machine
as 'Socket(s)'.
That is because lscpu uses a sysfs entry (cpu/cpuX/topology/core_siblings) to
get the number of sockets. For aarch64, the sysfs entry is set from MPIDR_EL1
register if the machine doesn't have ACPI PPTT. According to ARM Architecture
Reference Manual, the register shows the topology as the affinity, but doesn't
show the physical socket information.
There're such aarch64 machines because ARM SBBR v1.0 and v1.1 don't require
ACPI PPTT. SBBR v1.2 requires ACPI PPTT.
For the aarch64 machine, probably 'Cluster(s)' is good instead of 'Socket(s)'
according to linux/arch/arm64/kernel/topology.c:store_cpu_topology().
To get the number of sockets on the machine, SMBIOS Processor information (Type04)
is useful for lscpu because the SMBIOS information is a mandatory
feature for the aarch64 machine which is based on ARM SBBR v1.0 and newer.
With these patches, lscpu shows as following on the machine:
For unprivileged user:
$ lscpu
Architecture: aarch64
...
Socket(s): -
Cluster(s): 4
...
For root:
# lscpu
Architecture: aarch64
...
Socket(s): 1
Cluster(s): 4
Masayoshi Mizuma (4):
lscpu: use cluster on aarch64 machine which doesn't have ACPI PPTT
lscpu-dmi: split to parse dmi table
lscpu: add helper to get physical sockets
lscpu: show physical socket on aarch64 without ACPI PPTT
sys-utils/lscpu-dmi.c | 90 +++++++++++++++++++++++++++++++++----------
sys-utils/lscpu.1 | 3 ++
sys-utils/lscpu.c | 75 ++++++++++++++++++++++++++++++++----
sys-utils/lscpu.h | 1 +
4 files changed, 142 insertions(+), 27 deletions(-)
--
2.27.0
