Forum > Windows

Seemingly Silly Question

(1/2) > >>

VoidPilot:

I was trawlling through the seti board and saw soehting that caught my eye at the time.  I started wondering about it much later on and my curiousity has been tweaked so i was wondering if anyone knew the answer to this.

Is it possible to get the GPU to process 2 seti WUs at the same time and if so, does it take each WU, say, 10% longer or 50% longer etc...

If this can be done, how does one do it

rgds

VP

Jason G:

--- Quote from: VoidPilot on 07 Jul 2010, 05:44:22 am ---Is it possible to get the GPU to process 2 seti WUs at the same time and if so, does it take each WU, say, 10% longer or 50% longer etc...
--- End quote ---

Short Answer 'Yes and No'.

In more detail, pre-Fermi Cuda capable cards are architected to do basically one thing at a time.  Context switches (if doing multiple things at once) in older drivers & hardware, that usually fail for memory or other resource reasons, because of the physical memory model used by XP style drivers.  The Fermi cards have hardware devoted to context switching of applications, at least in the WDDM ( vista/win7 ) device driver model, which enables multiple Cuda contexts to be run at once. 

This new driver model allows each application to be isolated ( ignoring diver bugs) and so theoretically use the full resources of the card, by paging things in and out.  That's an expensive process across the PCI exoress bus, so overloading the cards wouldn't be advised, however current Fermi applications don't use the whole card's resources.  That means that some gains have been seem by running, on the Fermi's under the newer driver/OS, more instances can be run.  For now, running two instances makes each task run slower, but the total throughput seems to increase by about 50% on GTX 480.  I would expect, though, that figure to reduce greatly as we use more resources to speed thins up, and take advantage of greater capabilities in the Cuda framework.

That's acheived in Boinc using the anonymous platform, setting the number of GPUs needed to say 0.5.  As I suggested, the value of doing this will likely reduce, but it is something that may (or may not) help in the short term if you have a Fermi card running with WDDM drivers.  ( I doubt it will work on previous generation hardware/drivers)

Hope that helps, Jason

Raistmer:
And for pre-FERMI NV GPUs it was tested few times with negative result - total performance dropped.

VoidPilot:
J, R

thnx

VP

hellsheep:
I'm going to assume for any performance increase with the fermi's we require nVIDIA to release some new CUDA files of some sort? Maybe work on newer drivers too?

Navigation

[0] Message Index

[#] Next page