/proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

AcId · 2010-09-08 20:33:47

I've recently gone from Arch i686 to Arch x86_64, and now /proc/cpuinfo shows only one core even though it's a dual-core CPU.

cat /proc/cpuinfo

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 23
model name      : Intel(R) Core(TM)2 Duo CPU     P8400  @ 2.26GHz
stepping        : 6
cpu MHz         : 2266.542
cache size      : 3072 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
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 lm constant_tsc up arch_perfmon pebs bts rep_good aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 lahf_lm tpr_shadow vnmi flexpriority
bogomips        : 4534.96
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

Have anyone experienced similar problems on x86_64?
Could it possibly be a kernel related error?

/AcId

Last edited by AcId (2010-09-08 21:33:27)

munkyeetr · 2010-09-08 20:55:07

I haven't had it report number of cores wrong...but I have had it occasionally report cpu MHz = 1000.000 instead of 2000.000 as it should be.

ewaller · 2010-09-08 21:10:19

Anything interesting in dmesg ? Look for 'CPU' or 'processor'

AcId · 2010-09-08 21:22:54

dmesg shows some iterensting info about "Unsupported number of siblings" ?

dmesg | grep CPU:

SMP: Allowing 1 CPUs, 0 hotplug CPUs
setup_percpu: NR_CPUS:16 nr_cpumask_bits:16 nr_cpu_ids:1 nr_node_ids:1
PERCPU: Embedded 29 pages/cpu @ffff880001800000 s88832 r8192 d21760 u2097152
SLUB: Genslabs=13, HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
        RCU-based detection of stalled CPUs is disabled.
        Verbose stalled-CPUs detection is disabled.
CPU: Unsupported number of siblings 2
mce: CPU supports 6 MCE banks
CPU0: Thermal monitoring enabled (TM2)
weird, boot CPU (#0) not listed by the BIOS.
Brought up 1 CPUs

AcId · 2010-09-08 21:32:28

I found that the error was because i was booting with kernel flag "acpi=off", due to increadibly slow bootup (bootup extended from 10-15 secs to about 3 minutes ).

I'll mark this thread as solved, and see if i can find another solution to the slow bootup

ewaller · 2010-09-08 21:36:02

This Gentoo thread may help: http://forums.gentoo.org/viewtopic-t-778610.html

It talks about configuring the kernel, but don't panic just yet. Towards the bottom they suggest some things to add to the kernel command line in grub. The thread ended happily when the OP stated he turned on hyper threading in the BIOS. Give it a read and see if the simpler suggestions help.

By the way, Pappy_Mcfae, one of the posters, spends a huge amount of his time supporting kernel build configurations. He is a great asset to Gentoo.

Arch Linux

#1 2010-09-08 20:33:47

/proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

#2 2010-09-08 20:55:07

Re: /proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

#3 2010-09-08 21:10:19

Re: /proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

#4 2010-09-08 21:22:54

Re: /proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

#5 2010-09-08 21:32:28

Re: /proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

#6 2010-09-08 21:36:02

Re: /proc/cpuinfo shows only 1 core on dual-core CPU [SOLVED]

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