Re: [AMBER] AMBER 14 DPFP single energy calculations inconsistent

From: Jason Swails <>
Date: Thu, 29 Jan 2015 21:26:05 -0500

On Thu, Jan 29, 2015 at 9:14 PM, Scott Le Grand <>

> Hey Jason, I found the root cause and checked in a fix.
> If I put a printf into any CUDA kernel, that's the end of its performance.
> Printf is a hog. It's only useful for debugging purposes.

​That's what I was suggesting it be used for. Basically what I was curious
about was whether or not any of the GB tests in our test suite hit the code
path where dr didn't get initialized. If it did, that would seem (to me)
to be clear evidence that that code path is not illegal/unusual (i.e.,
indicative of bad parameters). If that printf is never triggered during
the test suite, the parameters may be unusual. I certainly wasn't
suggesting it be left in permanently. I'll take a look if I have time.

> The beginning
> of this thread has links to the data to repro this behavior. It's weird
> that we never saw this before.
> Just initialializing PMEFloat dr does the trick. The bug is fixed.

​I saw the commit log :).


Jason M. Swails
Rutgers University
Postdoctoral Researcher
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Received on Thu Jan 29 2015 - 18:30:04 PST
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