I only see half of the cores being used for this on my device

[rugk]

This is what htop shows me when it is running:

I wonder why it does not use all cores, but only half of them, that is suboptimal of course. I never remember having configured anything here like the core count or assigning them to the container or so.

System

Fedora CoreOS

I am running Nextcloud 27 in a podman container with the official image.

$ rpm-ostree status
State: idle
AutomaticUpdatesDriver: Zincati
  DriverState: active; periodically polling for updates (last checked Mon 2023-08-07 14:21:54 UTC)
Deployments:
● fedora:fedora/x86_64/coreos/stable
                  Version: 38.20230709.3.0 (2023-07-24T12:25:01Z)
$ podman version 4.5.1
$ lscpu
Architecture:            x86_64
  CPU op-mode(s):        32-bit, 64-bit
  Address sizes:         39 bits physical, 48 bits virtual
  Byte Order:            Little Endian
CPU(s):                  8
  On-line CPU(s) list:   0,2,4,6
  Off-line CPU(s) list:  1,3,5,7
Vendor ID:               GenuineIntel
  BIOS Vendor ID:        GenuineIntel
  Model name:            Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
    BIOS Model name:     Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz  CPU @ 2.0GHz
    BIOS CPU family:     12
    CPU family:          6
    Model:               142
    Thread(s) per core:  1
    Core(s) per socket:  4
    Socket(s):           1
    Stepping:            11
    CPU(s) scaling MHz:  39%
    CPU max MHz:         4600.0000
    CPU min MHz:         0.0000
    BogoMIPS:            3999.93
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art
                          arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1
                          sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault invpcid_single ssbd ibrs ibpb stibp tpr_shadow vnmi fl
                         expriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida ara
                         t pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear flush_l1d arch_capabilities
Virtualization features: 
  Virtualization:        VT-x
Caches (sum of all):     
  L1d:                   128 KiB (4 instances)
  L1i:                   128 KiB (4 instances)
  L2:                    1 MiB (4 instances)
  L3:                    8 MiB (1 instance)
NUMA:                    
  NUMA node(s):          1
  NUMA node0 CPU(s):     0,2,4,6
Vulnerabilities:         
  Itlb multihit:         KVM: Mitigation: VMX disabled
  L1tf:                  Not affected
  Mds:                   Mitigation; Clear CPU buffers; SMT disabled
  Meltdown:              Not affected
  Mmio stale data:       Mitigation; Clear CPU buffers; SMT disabled
  Retbleed:              Mitigation; IBRS
  Spec store bypass:     Mitigation; Speculative Store Bypass disabled via prctl
  Spectre v1:            Mitigation; usercopy/swapgs barriers and __user pointer sanitization
  Spectre v2:            Mitigation; IBRS, IBPB conditional, RSB filling, PBRSB-eIBRS Not affected
  Srbds:                 Mitigation; Microcode
  Tsx async abort:       Not affected
[root@minipure admrugk]# lscpu
Architecture:            x86_64
  CPU op-mode(s):        32-bit, 64-bit
  Address sizes:         39 bits physical, 48 bits virtual
  Byte Order:            Little Endian
CPU(s):                  8
  On-line CPU(s) list:   0,2,4,6
  Off-line CPU(s) list:  1,3,5,7
Vendor ID:               GenuineIntel
  BIOS Vendor ID:        GenuineIntel
  Model name:            Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
    BIOS Model name:     Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz  CPU @ 2.0GHz
    BIOS CPU family:     12
    CPU family:          6
    Model:               142
    Thread(s) per core:  1
    Core(s) per socket:  4
    Socket(s):           1
    Stepping:            11
    CPU(s) scaling MHz:  52%
    CPU max MHz:         4600.0000
    CPU min MHz:         0.0000
    BogoMIPS:            3999.93
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art
                          arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1
                          sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault invpcid_single ssbd ibrs ibpb stibp tpr_shadow vnmi fl
                         expriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida ara
                         t pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear flush_l1d arch_capabilities
Virtualization features: 
  Virtualization:        VT-x
Caches (sum of all):     
  L1d:                   128 KiB (4 instances)
  L1i:                   128 KiB (4 instances)
  L2:                    1 MiB (4 instances)
  L3:                    8 MiB (1 instance)
NUMA:                    
  NUMA node(s):          1
  NUMA node0 CPU(s):     0,2,4,6
Vulnerabilities:         
  Itlb multihit:         KVM: Mitigation: VMX disabled
  L1tf:                  Not affected
  Mds:                   Mitigation; Clear CPU buffers; SMT disabled
  Meltdown:              Not affected
  Mmio stale data:       Mitigation; Clear CPU buffers; SMT disabled
  Retbleed:              Mitigation; IBRS
  Spec store bypass:     Mitigation; Speculative Store Bypass disabled via prctl
  Spectre v1:            Mitigation; usercopy/swapgs barriers and __user pointer sanitization
  Spectre v2:            Mitigation; IBRS, IBPB conditional, RSB filling, PBRSB-eIBRS Not affected
  Srbds:                 Mitigation; Microcode
  Tsx async abort:       Not affected
[root@minipure admrugk]# htop
[root@minipure admrugk]# podman --version
podman version 4.5.1
[root@minipure admrugk]# lscpu
Architecture:            x86_64
  CPU op-mode(s):        32-bit, 64-bit
  Address sizes:         39 bits physical, 48 bits virtual
  Byte Order:            Little Endian
CPU(s):                  8
  On-line CPU(s) list:   0,2,4,6
  Off-line CPU(s) list:  1,3,5,7
Vendor ID:               GenuineIntel
  BIOS Vendor ID:        GenuineIntel
  Model name:            Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
    BIOS Model name:     Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz  CPU @ 2.0GHz
    BIOS CPU family:     12
    CPU family:          6
    Model:               142
    Thread(s) per core:  1
    Core(s) per socket:  4
    Socket(s):           1
    Stepping:            11
    CPU(s) scaling MHz:  39%
    CPU max MHz:         4600.0000
    CPU min MHz:         0.0000
    BogoMIPS:            3999.93
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art
                          arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1
                          sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault invpcid_single ssbd ibrs ibpb stibp tpr_shadow vnmi fl
                         expriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida ara
                         t pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear flush_l1d arch_capabilities
Virtualization features: 
  Virtualization:        VT-x
Caches (sum of all):     
  L1d:                   128 KiB (4 instances)
  L1i:                   128 KiB (4 instances)
  L2:                    1 MiB (4 instances)
  L3:                    8 MiB (1 instance)
NUMA:                    
  NUMA node(s):          1
  NUMA node0 CPU(s):     0,2,4,6
Vulnerabilities:         
  Itlb multihit:         KVM: Mitigation: VMX disabled
  L1tf:                  Not affected
  Mds:                   Mitigation; Clear CPU buffers; SMT disabled
  Meltdown:              Not affected
  Mmio stale data:       Mitigation; Clear CPU buffers; SMT disabled
  Retbleed:              Mitigation; IBRS
  Spec store bypass:     Mitigation; Speculative Store Bypass disabled via prctl
  Spectre v1:            Mitigation; usercopy/swapgs barriers and __user pointer sanitization
  Spectre v2:            Mitigation; IBRS, IBPB conditional, RSB filling, PBRSB-eIBRS Not affected
  Srbds:                 Mitigation; Microcode
  Tsx async abort:       Not affected

Asked ChatGPT and it gave me a list of like 10 different reasons why that could be hmm. Some replies:

• Check Task Manager Inside the Container is unfortunately not easily doable as neither htop, nor top nor ps are available in the container.

• updates are all done, this system is stable

• Hyper-Threading (HT): Your CPU doesn't seem to support Hyper-Threading (HT) based on the Thread(s) per core: 1 information. However, some systems have BIOS settings that allow enabling/disabling HT-like features. Make sure any such settings are configured correctly.

  Yes it says that, but why. The Intel website says it has indeed 8 threads and 4 cores, so maybe that is the problem, but how to configure that (on a server…)? Can I really (only) configure that in the BIOS, if I even can do that there hmm?

Or is it some virtualization i.e. podman problem hmm?

[marcelklehr]

CPU(s):                  8
  On-line CPU(s) list:   0,2,4,6
  Off-line CPU(s) list:  1,3,5,7

What does Off-line CPU(s) mean here? Seems suspicious

[marcelklehr]

No idea.

[rugk]

Asked now on the Purism forums.

[javierat]

What about this solution? https://ubuntu-mate.community/t/after-some-last-updates-i-only-have-4-cores-have-8-cores/20680?page=2

[rugk]

Ah sorry I forgot to also explain the solution here. You can find it in detail in my links, but the TL;DR is:

• It is a deliberate security mitigation against CPU vulnerabilities that disables SMT (Hyper-Threading). The kernel parameter nosmt aka “No Simultaneous MultiThreading” is used for that. See the kernel reference.
• You could remove that kernel parameter to have it use all cores, but really that seems to be an acceptable performanxe tradeoff given it may be less than 10% impact for better security.

As such, this is solved.