Forum > GPU crunching

Why a fallback mode.

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efmer (fred):
Why do the GPU application still have a fallback mode.
In theory this is a nice feature, but the speed difference between CPU and GPU is way to high.
Whenever this happens on my machine, all CPU fallback tasks end up in timeout errors.
The only good thing is that it doesn't trash all work at a higher rate.

Jason G:

--- Quote from: efmer (fred) on 04 Dec 2011, 05:20:16 am ---Why do the GPU application still have a fallback mode.
In theory this is a nice feature, but the speed difference between CPU and GPU is way to high.
Whenever this happens on my machine, all CPU fallback tasks end up in timeout errors.
The only good thing is that it doesn't trash all work at a higher rate.

--- End quote ---

? no CPU fallback in x41g Fred.

efmer (fred):

--- Quote from: Jason G on 04 Dec 2011, 05:25:43 am ---? no CPU fallback in x41g Fred.

--- End quote ---
Did I say anything?

Another question do the new drivers 285.62 with X41g use up more GPU memory.
I use to run my 590 with <COUNT>0.25, I set this back to 0.5.

Jason G:

--- Quote from: efmer (fred) on 04 Dec 2011, 05:48:53 am ---Did I say anything?

Another question do the new drivers 285.62 with X41g use up more GPU memory.
I use to run my 590 with <COUNT>0.25, I set this back to 0.5.
--- End quote ---

Shouldn't do, there aren't any new allocations, but we have noticed variability with different drivers.  So far as we've been able to figure most of that is to do with OS & CUFFT libraries, as the actual memory the apps explicitly allocate is pretty small ( ~90meg or so, listed in stderr).  Apparently with effort the app can still 'just' run on a 256meg card, though stock won't, and IIRC some drivers won't leave enough VRAM at all.

Jason

efmer (fred):
After removing the new driver and installing the old one. The problem was still there.
It took me a while to see that the SLI on the 590 was activated by the new driver.
That was something X41g didn't like at all. So after that 0.25 worked again without some of the tasks dropping out.
The new driver did enable the adaptive power.... ::)

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