How to fix that only one out of four cores of my CPU is detected?

12.04 hardware cpu multi-core

11,650

Holy macaroni. I apparently solved the issue. In short:

I changed the BIOS value Installer OS select to Other (the alternative being Windows)
I prayed and tried to boot WITHOUT the nolapic kernel boot parameter.
It started Ubuntu like a charm (not sure about the impact of praying though)

The lscpu now gives

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    1
Core(s) per socket:    4
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 23
Stepping:              10
CPU MHz:               2336.000
BogoMIPS:              4666.66
L1d cache:             32K
L1i cache:             32K
L2 cache:              2048K
NUMA node0 CPU(s):     0-3

I cross validated with top while running couple of computation intensive processes

3504 username   20   0  139m  47m 4308 R  100  1.2   4:57.11 R                  
3444 username   20   0  140m  47m 4316 R   99  1.2   5:24.08 R

I can finally heat my flat

Thanks a lot for your help and leads. I'm not so sure what I actually did, but it works. Special thanks for the BIOS lead. I would have never thought about messing around with the options...

11,650

Qiou Bi

Updated on September 18, 2022

Comments

Qiou Bi over 1 year

I have an Acer Aspire M5640/M3640 PC, featuring a Intel Core 2 Q8200 (Quad-core) processor running Ubuntu 12.04.

Now it seems to only recognize just one CPU core. lscpu outputs:

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                1
On-line CPU(s) list:   0
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 23
Stepping:              10
CPU MHz:               2333.403
BogoMIPS:              4666.80
L1d cache:             32K
L1i cache:             32K
L2 cache:              2048K
NUMA node0 CPU(s):     0

I would have expected to have Core(s) per socket and CPU(s) to have 4 listed as value here.

An important note is that I can't boot it regularly, but I need the nolapic kernel boot parameter to avoid a hard freeze during boot.

Speaking of booting, the firmware version is Version: R01-C2

Any thoughts on the ability to use all four cores will be highly appreciated.

More info

dmesg gives:

[    0.000000] Nvidia board detected. Ignoring ACPI timer override.
[    0.000000] If you got timer trouble try acpi_use_timer_override
[    0.000000] SFI: Simple Firmware Interface v0.81 http://simplefirmware.org
[    0.000000] Intel MultiProcessor Specification v1.4
[    0.000000] MPTABLE: OEM ID: nVidia  
[    0.000000] MPTABLE: Product ID: MCP73       
[    0.000000] MPTABLE: APIC at: 0xFEE00000
[    0.000000] Processor #0 (Bootup-CPU)
[    0.000000] Processor #1
[    0.000000] Processor #2
[    0.000000] Processor #3
[    0.000000] IOAPIC[0]: apic_id 4, version 17, address 0xfec00000, GSI 0-23
[    0.000000] Processors: 4
[    0.000000] SMP: Allowing 4 CPUs, 0 hotplug CPUs

and lshw -class cpu

  *-cpu                   
       description: CPU
       product: Intel(R) Core(TM)2 Quad CPU    Q8200  @ 2.33GHz
       vendor: Intel Corp.
       physical id: 4
       bus info: cpu@0
       version: Intel(R) Core(TM)2 Quad CPU    Q8200  @ 2.33GHz
       serial: To Be Filled By O.E.M.
       slot: SOCKET775 M/B
       size: 2333MHz
       capacity: 2333MHz
       width: 64 bits
       clock: 333MHz
       capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm dtherm
       configuration: cores=4 enabledcores=4 threads=4
  *-processor UNCLAIMED
       description: Co-processor
       product: MCP73 Co-processor
       vendor: NVIDIA Corporation
       physical id: 3.3
       bus info: pci@0000:00:03.3
       version: a2
       width: 32 bits
       clock: 66MHz
       capabilities: bus_master
       configuration: latency=0 maxlatency=1 mingnt=3
       resources: memory:fce80000-fcefffff

and dmidecode:

BIOS Information
    Vendor: American Megatrends Inc.
    Version: R01-C2
    Release Date: 02/26/2009
    Address: 0xF0000
    Runtime Size: 64 kB
    ROM Size: 1024 kB
    Characteristics:
            ISA is supported
            PCI is supported
            PNP is supported
            APM is supported
            BIOS is upgradeable
            BIOS shadowing is allowed
            ESCD support is available
            Boot from CD is supported
            Selectable boot is supported
            BIOS ROM is socketed
            EDD is supported
            5.25"/1.2 MB floppy services are supported (int 13h)
            3.5"/720 kB floppy services are supported (int 13h)
            3.5"/2.88 MB floppy services are supported (int 13h)
            8042 keyboard services are supported (int 9h)
            Serial services are supported (int 14h)
            Printer services are supported (int 17h)
            CGA/mono video services are supported (int 10h)
            ACPI is supported
            USB legacy is supported
            LS-120 boot is supported
            ATAPI Zip drive boot is supported
            BIOS boot specification is supported
            Targeted content distribution is supported
    BIOS Revision: 8.15

System Information
    Manufacturer: ACER
    Product Name: Aspire M5640/M3640
    Version: R01-C2
    Serial Number: 91EER71ZCP93401DDA1800
    UUID: Not Present
    Wake-up Type: Power Switch
    SKU Number: To Be Filled By O.E.M.
    Family: To Be Filled By O.E.M.

Base Board Information
    Manufacturer: ACER
    Product Name: MCP73PV
    Version: NVIDIA MCP73
    Serial Number: 000000000
    Asset Tag: To Be Filled By O.E.M.
    Features:
            Board is a hosting board
            Board is replaceable
    Location In Chassis: To Be Filled By O.E.M.
    Chassis Handle: 0x0003
    Type: Motherboard
    Contained Object Handles: 0

Qiou Bi over 11 years

Thanks for your valuable comment. I added the lshw -class cpu command output and it seems that the CPU is `Intel(R) Core(TM)2 Quad CPU Q8200 @ 2.33GHz'. I don't know whether this helps. I will try 12.10 live CD and keep posted.
Qiou Bi over 11 years

There you go, dmidecode seemed to work (I edited the original post).
Qiou Bi over 11 years

let us continue this discussion in chat