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[Robert Caulk <question677951@xxxxxxxxxxxxxxxxxxxxx>]

Question #677951 on Yade changed:
https://answers.launchpad.net/yade/+question/677951

Robert Caulk posted a new comment:
BTW:

>>Why GPU is slower than CPU?

In order to use the GPU, you need to reorgnize the data into a format
that the GPU can understand and send the data through PCIe (and don't
forget, this is a round trip ticket :-) ). This roundtrip costs time.
Thus, there is some break even point where the cost to organize and send
the data is equivalent to the time gained by solving the system on the
GPU itself. Hence somewhere between 30-60k spheres. Beyond that, the GPU
starts "paying for itself" by solvingthe system fast enough that it is
worth it to send the data on that round trip.

Of course, this all depends on hardware and simulation etc, but we found
that for 350k spheres the GPU saves about 50% time compared to CPU.

And finally, if you want specific flow solver stats, use:

flow.getCHOLMODPerfTimings = True [1]

[1]https://yade-
dem.org/doc/yade.wrapper.html#yade.wrapper.FlowEngine.getCHOLMODPerfTimings

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