[Beowulf] Re: GPU Beowulf Clusters (Jon Forrest)

[Jeff Johnson]

On 1/28/10 12:00 PM, Jon Forrest <jlforrest at berkeley.edu> wrote:
> A GPU cluster is different from a traditional
> HPC cluster in several ways:
>
> 1) The CPU speed and number of cores are not that important because 
> most of the computing will be done inside the GPU.
The GPU will be doing the specific operations called in the application 
but you need enough CPU to keep the memory operations and PCI I/O 
handled to feed the GPU.

> 2) Serious GPU boards are large enough that they don't easily fit into 
> standard 1U pizza boxes. Plus, they require more power than the 
> standard power supplies in such boxes can provide. I'm not familiar 
> with the boxes that therefore should be used in a GPU cluster.
There are 1U systems designs that use a passively cooled GPU that relies 
on chassis cooling infrastructure like CPUs do that work well. They are 
matched with the correct power supply size to support the GPU as well as 
the CPUs, memory, disk, etc.
> 3) Ideally, I'd like to put more than one GPU card in each computer 
> node, but then I hit the issues in #2 even harder.
Not in a 1U system unless you use the nVidia S1070 external GPU chassis. 
Even then, if your application can be bottlenecked by having less than 
full PCIex16 bandwidth to the GPUs then the S1070 approach would be less 
than optimal compared to a system that had two dedicated, full speed 
PCIex16 slots.

--Jeff

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