Re: [AMBER] CUDA test failed

From: Jason Swails <>
Date: Fri, 10 Oct 2014 12:25:21 -0400

On Fri, Oct 10, 2014 at 6:42 AM, Niels Geudens <>

> Hi all,
> I recently compiled amber14 on my computer. I performed tests for sander
> and sander.MPI without any problems. However, when I run the tests for
> pmemd.CUDA, there are 37 comparisons that fail, some with rather large
> errors. I attached the log-file. Can someone tell me if these problems are
> to be expected or troublesome? Could it be due to a compiler-problem?

‚ÄčUnfortunately, the pmemd.cuda tests have this problem sometimes. The
larger errors should occur for the stochastic tests (ntt=2 and ntt=3 -- the
name often tells you if one of those thermostats is involved).

The problem is that the random number generators are different on each GPU
model. As a result, it was impossible with the Amber 14 code to design a
test that would give identical results on all GPUs, even if you specified
the initial seed. As a result, the only cards that all tests pass for are
the cards that Ross used to create the test files in the first place.

So as long as the diffs appear in some kind of "ntt2" or "ntt3" test
(Andersen or Langevin thermostats), and the remaining diffs are small, you
should be fine. FWIW, 37 sounds about the right number to me.


Jason M. Swails
Rutgers University
Postdoctoral Researcher
AMBER mailing list
Received on Fri Oct 10 2014 - 09:30:02 PDT
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