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Old 10-29-2013, 08:02 PM   #1
vicky007aggrwal
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cpuinfo interpretation needed


I have hard time in understanding the below provided cpuinfo , To me it looks like the machine has 2 physical processors with 8 core each but the output for below command is 32
Quote:
grep ^processor /proc/cpuinfo | wc -l ==> 32
grep 'physical id' /proc/cpuinfo | sort | uniq | wc -l ==>2
grep 'cpu cores' /proc/cpuinfo|uniq ==> 8
grep 'sibling' /proc/cpuinfo|uniq ==> 16
I want to understand why the processor count is 32 as the number of physical machines are 2 & with 8 core each then ideally the processor count should be 16
please help me in understanding the gaps in my knowledge.


cpuinfo file output
Quote:
cat /proc/cpuinfo |egrep 'processor|vendor_id|physical id|siblings|core id|cpu cores|model'
processor : 0
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 0
cpu cores : 8
processor : 1
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 1
cpu cores : 8
processor : 2
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 2
cpu cores : 8
processor : 3
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 3
cpu cores : 8
processor : 4
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 4
cpu cores : 8
processor : 5
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 5
cpu cores : 8
processor : 6
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 6
cpu cores : 8
processor : 7
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 7
cpu cores : 8
processor : 8
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 0
cpu cores : 8
processor : 9
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 1
cpu cores : 8
processor : 10
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 2
cpu cores : 8
processor : 11
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 3
cpu cores : 8
processor : 12
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 4
cpu cores : 8
processor : 13
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 5
cpu cores : 8
processor : 14
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 6
cpu cores : 8
processor : 15
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 7
cpu cores : 8
processor : 16
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 0
cpu cores : 8
processor : 17
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 1
cpu cores : 8
processor : 18
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 2
cpu cores : 8
processor : 19
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 3
cpu cores : 8
processor : 20
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 4
cpu cores : 8
processor : 21
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 5
cpu cores : 8
processor : 22
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 6
cpu cores : 8
processor : 23
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 0
siblings : 16
core id : 7
cpu cores : 8
processor : 24
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 0
cpu cores : 8
processor : 25
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 1
cpu cores : 8
processor : 26
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 2
cpu cores : 8
processor : 27
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 3
cpu cores : 8
processor : 28
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 4
cpu cores : 8
processor : 29
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 5
cpu cores : 8
processor : 30
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 6
cpu cores : 8
processor : 31
vendor_id : GenuineIntel
model : 45
model name : Intel(R) Xeon(R) CPU E5-2660 0 @ 2.20GHz
physical id : 1
siblings : 16
core id : 7
cpu cores : 8

Last edited by vicky007aggrwal; 10-29-2013 at 08:20 PM.
 
Old 10-29-2013, 08:18 PM   #2
suicidaleggroll
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Hyperthreading

http://ark.intel.com/products/64584/
http://en.wikipedia.org/wiki/Hyper-threading
 
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Old 10-29-2013, 08:37 PM   #3
vicky007aggrwal
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can you please elaborate a bit ,what do we'll call this processor as ,is it correct to say "dual processor 8 core" or something else
 
Old 10-29-2013, 09:14 PM   #4
suicidaleggroll
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It's a dual 8-core machine with Hyperthreading.

Hyperthreading presents to the OS two virtual cores per real core. If you're doing a lot of highly varied tasks simultaneously it can help, but if you're doing a lot of similar tasks it just slows things down. Given my usage, I always make it a habit to disable Hyperthreading on all processing machines I build. Disabling it generally gives me a 10-20% speed boost under my typical usage. You can generally do this in the BIOS.
 
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Old 10-29-2013, 10:27 PM   #5
TobiSGD
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Quote:
Originally Posted by suicidaleggroll View Post
It's a dual 8-core machine with Hyperthreading.

Hyperthreading presents to the OS two virtual cores per real core. If you're doing a lot of highly varied tasks simultaneously it can help, but if you're doing a lot of similar tasks it just slows things down. Given my usage, I always make it a habit to disable Hyperthreading on all processing machines I build. Disabling it generally gives me a 10-20% speed boost under my typical usage. You can generally do this in the BIOS.
It doesn't have to be that varied. For my use case, which is mostly compiling software Hyperthreading can give a good performance boost. It also depends on the CPU in use, Hyperthreading has evolved since its introduction in Pentium 4 class machines and can now give better performance where it was slower before.
I recommend to run benchmarks for your specific use-case whenever you built a machine with a different CPU architecture.
 
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Old 10-30-2013, 09:46 AM   #6
suicidaleggroll
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Quote:
Originally Posted by TobiSGD View Post
I recommend to run benchmarks for your specific use-case whenever you built a machine with a different CPU architecture.
I have. Latest machine uses a pair of Xeon X5690, it still takes a 10-20% performance hit with HT enabled.
 
Old 11-02-2013, 08:23 PM   #7
vicky007aggrwal
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Thank you so much for your inputs, it really helped me
 
  


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