From: Axel Kohlmeyer (akohlmey_at_gmail.com)
Date: Mon Jun 06 2011 - 06:50:16 CDT
On Mon, Jun 6, 2011 at 7:39 AM, Ajasja Ljubetič
> Dear all,
> I'm still in still in the "dream-up" phase of designing my GPU node. Gammer
> mother boards with 3x PCI-E 8x are quite common, but I also found one with
you _have_ to have PCI-e v2.0 16x slots for the GPUs.
> 4x PCI-E 8x. Does it make sense to stuff four GPUs on one node? Can
no. you have only half the bandwidth with a PCI-e 8x slot and will hurt
you more than the 4th GPU will buy you. in my experience, you will
already run into memory bandwidth issues at 3 GPUs. the available
bandwidth is something like sufficient for 2.5 GPUs.
to have 4 GPUs and have them perform well, you need a (server)
mainboard with two southbridges.
> 6 cores feed 4 GPUs? What is the optimum ratio between cores and graphics
> cards? (Or how much over subscription is beneficial?)
if you run on a single node, you will have the largest benefit from
2x oversubscription. everything beyond that is most likely speedup
from the non-GPU part of the namd code.
> Thank you for your answers & Best regards,
> Ajasja Ljubetič
-- Dr. Axel Kohlmeyer akohlmey_at_gmail.com http://goo.gl/1wk0 Institute for Computational Molecular Science Temple University, Philadelphia PA, USA.
This archive was generated by hypermail 2.1.6 : Wed Feb 29 2012 - 15:57:14 CST