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javeree Guru
Joined: 29 Jan 2006 Posts: 455
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Posted: Fri Jun 21, 2013 10:31 am Post subject: weird ? cpuinfo |
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I have a PC with the CPUinfo as quoted below. I am trying to understand how many physical CPUs there are, how many cores per CPU, if they are hyperthreading capable / enabled.
I see both have a physical id 0, so I suppose they reside on the same chip. However, they also have both core id 0, so this looks like there is also only a single core cpu.
As of this point, what I don't understand is why does one cpu say 'cpu cores 1' and the other 'cpu cores 0' ? I'd expect both to report 1.
Finally there is the field siblings, which says 1. I can interprete this as each CPU reporting ' I still have one sibling, so we are together 2' .
However, in some articles (like http://www.richweb.com/cpu_info), I find that I should expect here the total number of siblings, being two for a single core, hyperthreaded chip.
So how should I interprete this?
Quote: | processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 28
model name : Intel(R) Atom(TM) CPU N280 @ 1.66GHz
stepping : 2
microcode : 0x218
cpu MHz : 1000.000
cache size : 512 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
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 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm
bogomips : 3325.09
clflush size : 64
cache_alignment : 64
address sizes : 32 bits physical, 32 bits virtual
power management:
processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 28
model name : Intel(R) Atom(TM) CPU N280 @ 1.66GHz
stepping : 2
microcode : 0x218
cpu MHz : 1000.000
cache size : 512 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 0
apicid : 1
initial apicid : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
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 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm
bogomips : 3325.09
clflush size : 64
cache_alignment : 64
address sizes : 32 bits physical, 32 bits virtual
power management:
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In addition, I also ran lshw, an got the cpu related output below. now I see two cpus reporting different physical ids and each talking about two logical ideas ?
I'm getting more and more confused
Quote: |
*-core
description: Motherboard
product: 3641h
vendor: Hewlett-Packard
physical id: 0
serial: CZC1159L42
slot: Climbers
*-firmware
description: BIOS
vendor: American Megatrends Inc.
physical id: 0
version: 786R8 v1.04
date: 03/22/2011
size: 128KiB
capacity: 960KiB
capabilities: pci pnp upgrade shadowing escd cdboot bootselect edd int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot zipboot biosbootspecification netboot
*-cpu:0
description: CPU
product: Intel(R) Atom(TM) CPU N280 @ 1.66GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: 6.12.2
serial: 0001-06C2-0000-0000-0000-0000
slot: CPU 1
size: 1667MHz
capacity: 1750MHz
width: 32 bits
clock: 167MHz
capabilities: boot fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm cpufreq
configuration: cores=1 enabledcores=1 id=0 threads=2
*-cache:0
description: L1 cache
physical id: 5
slot: L1-Cache
size: 24KiB
capacity: 24KiB
capabilities: burst internal write-back data
*-cache:1
description: L2 cache
physical id: 6
slot: L2-Cache
size: 512KiB
capacity: 512KiB
capabilities: burst internal write-back unified
*-logicalcpu:0
description: Logical CPU
physical id: 0.1
width: 32 bits
capabilities: logical
*-logicalcpu:1
description: Logical CPU
physical id: 0.2
width: 32 bits
capabilities: logical
--
*-cpu:1
product: Intel(R) Atom(TM) CPU N280 @ 1.66GHz
vendor: Intel Corp.
physical id: 3
bus info: cpu@1
version: 6.12.2
serial: 0001-06C2-0000-0000-0000-0000
size: 1GHz
capacity: 1GHz
width: 32 bits
capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 xtpr pdcm movbe lahf_lm dtherm cpufreq
configuration: id=0
*-logicalcpu:0
description: Logical CPU
physical id: 0.1
width: 32 bits
capabilities: logical
*-logicalcpu:1
description: Logical CPU
physical id: 0.2
width: 32 bits
capabilities: logical
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Ant P. Watchman
Joined: 18 Apr 2009 Posts: 6920
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Posted: Fri Jun 21, 2013 2:13 pm Post subject: |
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You have one CPU, one real core, with two threads. |
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mvaterlaus Apprentice
Joined: 01 Oct 2010 Posts: 237 Location: Switzerland
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Posted: Fri Jun 21, 2013 2:15 pm Post subject: |
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hi,
because your cpu lists the ht flag (for hyper threading), imho, I assume that you have one cpu with one core. but be carefull with that answer because it depends on your kernel. if you have hyper threading disabled in your kernel, you have one cpu with 2 cores.
[edit] oh, I was to slow[/edit] |
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wcg Guru
Joined: 06 Jan 2009 Posts: 588
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javeree Guru
Joined: 29 Jan 2006 Posts: 455
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Posted: Mon Jun 24, 2013 11:35 am Post subject: |
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Thanks for showing the ht flag. and to show the detailed info on the CPU. The question is now clear for this particular cpu:
It is one chip, one core and hyperthreading.
What my 'confusion' is about, is more about why this results in this confusing cpuinfo.
What I would expect as output would be:
Quote: | processor : 0
physical id : 0
siblings : 2 (instead of 1)
core id : 0
cpu cores : 1
processor : 1
physical id : 0
siblings : 2 (instead of 1)
core id : 0
cpu cores : 1 (instead of 0) |
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albright Advocate
Joined: 16 Nov 2003 Posts: 2588 Location: Near Toronto
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Posted: Mon Jun 24, 2013 12:22 pm Post subject: |
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maybe this is just semantics but I would not say that a thread
is a sibling of itself; so the report that each thread has one
sibling can be understood as correct ... ??? _________________ .... there is nothing - absolutely nothing - half so much worth
doing as simply messing about with Linux ...
(apologies to Kenneth Graeme) |
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