[GE users] Implications of Hyperthread enabled CPUs and jobs

Neil Baker neil.baker at crl.toshiba.co.uk
Thu Nov 27 10:40:03 GMT 2008


Good suggestion.

 

With Hyper-threading enabled /proc/cpuinfo gives the following output:
http://pastebin.com/m6615d3e9

 

In Summary the only difference between the 4 logical CPUs is as follows:

 

Processor 0

1.	physical id     : 0
2.	siblings        : 2
3.	core id         : 0
4.	cpu cores       : 1

Processor 1

1.	physical id     : 0
2.	siblings        : 2
3.	core id         : 0
4.	cpu cores       : 1

Processor 2

1.	physical id     : 3
2.	siblings        : 2
3.	core id         : 3
4.	cpu cores       : 1

Processor 3

1.	physical id     : 3
2.	siblings        : 2
3.	core id         : 3
4.	cpu cores       : 1

Now I would have guessed that the physical id refers to each physical
processor.  If this assumption is correct, then processor 0 & 1 appear to be
exactly the same to the OS, when in fact one is a Hyper-threaded CPU.

 

I'll turn Hyper-threading off and report back.

 

Neil

 

  _____  

From: John Hearns [mailto:hearnsj at googlemail.com] 
Sent: 27 November 2008 10:23
To: users at gridengine.sunsource.net
Subject: Re: [GE users] Implications of Hyperthread enabled CPUs and jobs

 

You could also take one machine down, connect a monitor/keyboard and go into
the BIOS settings.

You can enable/disable hyperthreading from the BIOS, and see how this
affects your cpuinfo output,

and also your performance on that node.

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