[Beowulf] Register article on Linux State of the Union

Prentice Bisbal prentice.bisbal at rutgers.edu
Mon Apr 22 08:04:27 PDT 2013

Prentice Bisbal
Manager of Information Technology
Rutgers Discovery Informatics Institute (RDI2)
Rutgers University

On 04/18/2013 11:50 AM, Douglas Eadline wrote:
>> http://www.theregister.co.uk/2013/04/17/state_of_linux_2013/
>> Some interesting points from an HPC point of view:
>> "For example, for some kinds of workloads, the NUMA (non-uniform memory
>> access) problem is all-important. This is particularly true of distributed
>> application clusters. A long as a CPU in a cluster node is working on data
>> that exists locally, within the node's own memory or storage, processing
>> is fast. But as soon as that CPU needs to access data that exists on some
>> other node in the cluster - data that must pulled across some slow type of
>> transport, like an Ethernet link - performance can degrade rapidly. Some
>> Linux kernel developers would like to improve the CPU scheduler to handle
>> such situations better."
> I am puzzled by this paragraph. I don't follow the kernel development list
> anymore, but is there some kind of effort to support shared memory
> over Ethernet? I think "degrade rapidly" is a bit of an understatement.

I'm glad you caught that. I caught that, too, and was going to bring it 
up here, but never got around to it. After reading that paragraph, I 
started to question the rest of the article, but the rest seemed to be 
correct, as I recall.  I think the author confused NUMA with a 
distributed memory cluster architecture.


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