[Beowulf] getting a phi, dammit.

James Cownie jcownie at cantab.net
Tue Mar 5 11:28:17 PST 2013

Answering a little late, sorry...

And, up front, I work for Intel and even on Intel(r) Xeon Phi(c) coprocessor (yes, that is the official Intel branding!) software. (Though I've been on this list since w..a..y back, well before I worked for Intel!)

On 27 Feb 2013, at 21:01, Mark Hahn wrote:

> I find the PCIe/BIOS stuff quite dubious, though I suppose Phi is still
> relatively immature.  maybe the next version will be the one that will be
> generally applicable.  I suspect by contrast that I can buy a K20 card
> and drop it into most any gen1/2/3 PCIe x16 slot and it'll work (assuming
> I provide the right power and cooling, of course.)

The issue here is that because we offer 8GB of memory on the cards, some BIOSes are unable to map all of it through the PCI either due to bugs or failure to support so much memory. This is not the only people suffering from this problem, but it is true that cards (like many GPUs) with less memory do not need to worry about this.  So you need to make sure that whatever host system you are attempting to use can operate with a large PCI aperture 
that can map 8GB.
However, the larger memory capacity seems to be the right general approach, because it helps to enable bigger science.
(Indeed other threads here have been complaining that 8GB is too little memory).

-- Jim
James Cownie <jcownie at cantab.net>

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