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Old 12-14-2008, 09:01 PM   #1
tanveer
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Registered: Feb 2004
Location: e@rth
Distribution: RHEL-3/4/5,Gloria,opensolaris
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CPU architecture explanation with /proc/cpuinfo


Hi all,

Below are two servers with two different results with cpuinfo command. Why one is showing processor 0 to 4 and another showing only 0 and 1.
Both are dual core processor as far my knowledge as they have cpu core '2'.
Now I got another IBM server which shows processor 0 to 7 and cpu core '4'. Does is mean quad core? Also, in dual core processors with HT enable should siblings be showing a value '4' instead of '2'?

Server-1
---------
PHP Code:
[root@ ~]# cat /proc/cpuinfo 
processor       0
vendor_id       
GenuineIntel
cpu family      
6
model           
15
model name      
Intel(RXeon(RCPU            5160  3.00GHz
stepping        
6
cpu MHz         
3000.004
cache size      
4096 KB
physical id     
0
siblings        
2
core id         
0
cpu cores       
2
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 syscall lm pni monitor ds_cpl est tm2 cx16 xtpr ts
bogomips        
5947.39
clflush size    
64
cache_alignment 
64
address sizes   
36 bits physical48 bits virtual
power management
:

processor       1
vendor_id       
GenuineIntel
cpu family      
6
model           
15
model name      
Intel(RXeon(RCPU            5160  3.00GHz
stepping        
6
cpu MHz         
3000.004
cache size      
4096 KB
physical id     
3
siblings        
2
core id         
6
cpu cores       
2
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 syscall lm pni monitor ds_cpl est tm2 cx16 xtpr ts
bogomips        
5996.54
clflush size    
64
cache_alignment 
64
address sizes   
36 bits physical48 bits virtual
power management
:

processor       2
vendor_id       
GenuineIntel
cpu family      
6
model           
15
model name      
Intel(RXeon(RCPU            5160  3.00GHz
stepping        
6
cpu MHz         
3000.004
cache size      
4096 KB
physical id     
0
siblings        
2
core id         
1
cpu cores       
2
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 syscall lm pni monitor ds_cpl est tm2 cx16 xtpr ts
bogomips        
6291.45
clflush size    
64
cache_alignment 
64
address sizes   
36 bits physical48 bits virtual
power management
:

processor       3
vendor_id       
GenuineIntel
cpu family      
6
model           
15
model name      
Intel(RXeon(RCPU            5160  3.00GHz
stepping        
6
cpu MHz         
3000.004
cache size      
4096 KB
physical id     
3
siblings        
2
core id         
7
cpu cores       
2
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 syscall lm pni monitor ds_cpl est tm2 cx16 xtpr ts
bogomips        
5996.54
clflush size    
64
cache_alignment 
64
address sizes   
36 bits physical48 bits virtual
power management

Server-2
----------
PHP Code:
[root@ ~]# cat /proc/cpuinfo 
processor       0
vendor_id       
GenuineIntel
cpu family      
6
model           
15
model name      
Intel(RXeon(RCPU            5160  3.00GHz
stepping        
11
cpu MHz         
3000.006
cache size      
4096 KB
physical id     
0
siblings        
2
core id         
0
cpu cores       
2
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 syscall lm constant_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr lahf_lm
bogomips        
6004.09
clflush size    
64
cache_alignment 
64
address sizes   
38 bits physical48 bits virtual
power management
:

processor       1
vendor_id       
GenuineIntel
cpu family      
6
model           
15
model name      
Intel(RXeon(RCPU            5160  3.00GHz
stepping        
11
cpu MHz         
3000.006
cache size      
4096 KB
physical id     
0
siblings        
2
core id         
1
cpu cores       
2
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 syscall lm constant_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr lahf_lm
bogomips        
6000.05
clflush size    
64
cache_alignment 
64
address sizes   
38 bits physical48 bits virtual
power management

 
Old 12-15-2008, 09:36 AM   #2
johnsfine
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Registered: Dec 2007
Distribution: Centos
Posts: 5,083

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Quote:
Originally Posted by tanveer View Post
Below are two servers with two different results with cpuinfo command. Why one is showing processor 0 to 4 and another showing only 0 and 1.
The first shows processors 0 to 3, representing two physical processors with two cores each.

The second shows one physical processor with two cores.

How many physical processors did you think each has? If the second has two physical, then one is disabled. Check the BIOS settings.
If I'm reading it correctly, both have hyper threading capable hardware but both have hyper threading disabled by the BIOS.

Quote:
Now I got another IBM server which shows processor 0 to 7 and cpu core '4'. Does is mean quad core?
That is quad core. I don't think you gave enough info to distinguish quad core doubled by HT, vs. two physical processors quad core.

Quote:
Also, in dual core processors with HT enable should siblings be showing a value '4' instead of '2'?
Right. If HT is enabled the number of siblings will be double the number of cores.
 
Old 12-15-2008, 07:33 PM   #3
tanveer
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Registered: Feb 2004
Location: e@rth
Distribution: RHEL-3/4/5,Gloria,opensolaris
Posts: 489

Original Poster
Rep: Reputation: 37
Thanks for replying.
Do you know which option to check to enable HT in BIOS?
 
Old 12-16-2008, 08:18 AM   #4
johnsfine
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I haven't seen any consistency between BIOS's for that type of question. All I know how to do is carefully walk the entire menu tree of the BIOS looking. While doing that, also look for any BIOS settings that might turn on "advanced" or "manual" or other modes that might then cause it to display setting choices that are normally hidden. Obviously be more careful what you change inside normally hidden options, but you might need to enable some normally hidden options just to be able to enable HT.
 
  


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