[gmx-users] Log output of GPU accelerated GROMACS

[Mark Abraham]

No, it stems from a CUDA limitation, where if two+ ranks share a GPU then
mdrun can't get clean timing numbers.

Mark
On Jan 8, 2015 3:10 PM, "Ebert Maximilian" <m.ebert at umontreal.ca> wrote:

> Dear list,
>
> I was wondering why the log file does not always contains the same
> information. In one of my configurations I got the following information:
>
> GPU timings
>
> -----------------------------------------------------------------------------
>  Computing:                         Count  Wall t (s)      ms/step       %
>
> -----------------------------------------------------------------------------
>  Pair list H2D                       1251       0.563        0.450     0.2
>  X / q H2D                          50001       6.998        0.140     2.9
>  Nonbonded F kernel                 47500     212.118        4.466    86.7
>  Nonbonded F+ene k.                  1250       9.371        7.497     3.8
>  Nonbonded F+ene+prune k.            1251       9.759        7.801     4.0
>  F D2H                              50001       5.874        0.117     2.4
>
> -----------------------------------------------------------------------------
>  Total                                        244.683        4.894   100.0
>
> -----------------------------------------------------------------------------
>
> Force evaluation time GPU/CPU: 4.894 ms/4.012 ms = 1.220
> For optimal performance this ratio should be close to 1!
>
> But I never got this information in any other configuration using GPUs. Is
> this only part of the output if there is a problem with too much work for
> the GPU?
>
> Thank you very much,
>
> Max
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