"How it is possible to run on Titan e.g. JAC tests several times and in
each case obtain different result (errors in different stage of
calculation or different final results) ? Where is hidden that
"roulette" here ???"
The nondeterministic behavior I'm seeing from Titan is enough to throw
simulations (D.E. Shaw estimated the worst error one can tolerate is 1e-5,
I'm seeing 1e-3 in the IPS repro I found last week because random
individual bonded interactions are going AWOL every 50K iterations). But
it's also very had to detect unless one is running an algorithm with
deterministic output because the chaos of a nondeterministic algorithm is
more than enough to obscure it.
As to what is causing it, I have no idea at this point. Titan seems to
have similar texture issues as GTX4xx and GTX5xx, but there seems to be
something more going on here. And that's really hard to diagnose let alone
fix. I've tried a multitude of dirty tricks to try to convince the GPU to
behave, nothing works. Give NVIDIA time here. They'll do what it takes to
make things right. AMBER is too important to them to do otherwise.
Scott
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Received on Thu Jun 20 2013 - 08:30:04 PDT
