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Old 02-06-2008, 11:45 AM   #1
plemmons
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Multi -Core CPU Load Balancing RHEL 5


I have a eight core system with 64 GB of RAM running Redhat Enterprise 5. One of my users showed me a situation the other day where the machine was pretty much idle and he submitted 6 large Matlab jobs. The jobs were running fine, but where only running on 5 cores instead of 6 when a 6th core was at 0% utilization.

Can someone point me to some documentation that explains how RHEL 5 handles this type of load balancing, what the defaults are and how it can be modified/configured?

Thanks,

Steve
 
Old 02-07-2008, 04:59 AM   #2
syg00
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Get a decent sized system maybe ???.
(bad) joke ....

I'd be mildly surprised if this was a RH issue unless you have quotas or containers/cpusets in operation. Hopefully you'd be aware if you did. I'd be expecting the kernel (scheduler) to manage handing out processors to processes.
I don't run big RHEL, so I'll be interested to see what others have experienced and can suggest.
 
Old 02-07-2008, 08:07 AM   #3
plemmons
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Unless there are quotas or containers/cpusets setup by default, this is definitely not the case.

Another thing that I've noticed is that if two of these jobs end up on one core, and I renice one of them, it will typically move to a free processor. A round-a-bout solution, but we'd like these to distribute automatically.

Thanks,

Steve
 
Old 02-08-2008, 04:59 PM   #4
lazlow
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Plemmons

You are probably going to be in the minority of users in this case(quad core is more than most of us have). Since you are paying for the support (RHEL5 versus Centos5) why not get what you are paying for? If all else fails post the problem to bugzilla.
 
Old 02-08-2008, 06:38 PM   #5
syg00
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If re-nice works, then it ain't anything I suggested. As lazlow said, use what you pay for, and at least ask RH.
 
Old 02-24-2008, 04:24 AM   #6
munichtexan
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Quote:
Originally Posted by plemmons View Post
I have a eight core system with 64 GB of RAM running Redhat Enterprise 5. One of my users showed me a situation the other day where the machine was pretty much idle and he submitted 6 large Matlab jobs. The jobs were running fine, but where only running on 5 cores instead of 6 when a 6th core was at 0% utilization.

Can someone point me to some documentation that explains how RHEL 5 handles this type of load balancing, what the defaults are and how it can be modified/configured?

Thanks,

Steve
Just want to double check. What command line did you use to double check your core utilization?
 
  


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