Hi Ross & Jason,
After a couple of days of testing, one of the GPUs finally gave up so ultimately it was not too difficult to identify the problem. Just to be safe, I tested the other GPU as well, but this seems to be working fine according to the GPU validation suite. Thanks for sending me the link !
After checking the trajectory where the errors occurred, it didn't blow up or seemed to be suffering from other artifacts, so I'm guessing my approach should be more or less OK, at least for now. I know the scaled MD approach is still in it's infant stage, and will experiment with it some more in the coming time. Either way thanks for the tips and if I find something interesting/worrying I will let you know.
Kind regards,
Dieter
Dieter Buyst
NMR & structural analysis unit
Department of Organic and Marcromolecular Chemistry
Ghent University
Krijgslaan 281 S4
B-9000 Gent
Belgium
Tel.: +32(0)9-264-96-63
e-mail: Dieter.Buyst.UGent.be
web: htp://nmrstr.ugent.be
Op 18-sep.-2014, om 19:23 heeft Ross Walker <ross.rosswalker.co.uk> het volgende geschreven:
> Hi Dieter,
>
> ScaledMD is a very new and only slightly tested (and I think still
> undocumented method). It will take a lot of TLC in order to get it to
> work. Chances are this is not an issue with the GPU code but with the
> underlying ScaledMD theory, your simulation system and the appropriateness
> of the settings you are using. You should probably test this out on the
> CPU as well and see if it crashes - there you might get a better error
> message.
>
> If you are worried about your GPUs then I recommend burning them in
> properly before use and testing the reproducibility. You can use the
> following to do this:
>
> https://dl.dropboxusercontent.com/u/708185/GPU_Validation_Test.tar.gz
>
> All the best
> Ross
>
>
> On 9/18/14, 1:51 AM, "Dieter Buyst" <dieter.buyst.ugent.be> wrote:
>
>> Dear All,
>>
>> Quite recently we upgraded our MD computer (ubuntu 12.04 LTS, CUDA 5.0
>> and driver 340.24) with two EVGA GTX780 SC GPUs since the 780 Ti models
>> were not recommended due to the stability issues. After the installation
>> I performed the usual tests for running calculations on a single and both
>> GPUs at the same time. I did notice in both scenarios there were about 30
>> possible failures, but on inspection of the .diff files they were just
>> small errors in the last decimal place. Likewise, the benchmark suite
>> produced results which were in line with what can be expected for our
>> configuration.
>>
>> While experimenting with the Scaled_MD feature now available in Amber14,
>> both me and a colleague sometimes run into the error "cudaMempcpy
>> GpuBuffer :: Donwload failed unspecified launch failure". This doesn't
>> happen very often but does pop up when we're performing some longer runs.
>> I already checked the mailing archive for similar problems and it is
>> suggested that probably one of the GPUs is faulty and is causing these
>> problems. Now I just wanted to make sure I'm right and rule out whether
>> this error could happen due the nature of the scaled MD feature, given
>> it's brand new and possibly not fully tested yet ?
>>
>> In addition, I'm wondering if one can still trust the trajectory produced
>> during these errors or it's better to just start from scratch with a new
>> GPU ?
>>
>> Kind regards,
>>
>> Dieter
>>
>> Dieter Buyst
>> NMR & structural analysis unit
>> Department of Organic and Marcromolecular Chemistry
>> Ghent University
>> Krijgslaan 281 S4
>> B-9000 Gent
>> Belgium
>> Tel.: +32(0)9-264-96-63
>> e-mail: Dieter.Buyst.UGent.be
>> web: htp://nmrstr.ugent.be
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
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Received on Tue Sep 23 2014 - 03:00:03 PDT
