CUDA error: an illegal memory access was encountered

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Geemi Wellawatte

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Mar 3, 2021, 3:31:20 PM3/3/21
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Hi all, 

I am trying to do a CG simulation with only 16 particles. I have the initial particle positions and I am creating a hoomd system from a snapshot. I am adding the topology information manually. The bond, angle, dihedral and pair potentials are table potentials which are set from the respective files.

Currently I am facing the following issues,

1. Even though my system only contains 16 particles, I have to set a larger box size. Eg: hoomd.data.boxdim(L=200)

2. After starting my equilibration, dynamic data will only be updated for 3 steps. These will not be updated after that. Sometimes the output will show ** run complete ** but it gives the following error. Is this something related to the potentials I've used? Please help me to figure this out.

** run complete **
**ERROR**: an illegal memory access was encountered before /hoomd/GPUArray.h:160
terminate called after throwing an instance of 'std::runtime_error'
  what():  CUDA Error
Aborted (core dumped)

I have attached the script, table potentials and the data here. 

Any help to get my simulation started is highly appreciated!

Thanks,
Geemi
data_arrays.npz
script_n_potentials.zip

Joshua Anderson

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Mar 4, 2021, 10:31:25 AM3/4/21
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Geemi,

Thanks for the script. The first steps in debugging CUDA errors are to try running on the CPU (--mode=cpu) or enable GPU error checking (--gpu_error_checking). In both cases I get this when I run your script:

** starting run **
**ERROR**: Table bond out of bounds

This error is raised when the length of one of your bonds r is smaller than the rmin or larget than the rmax of your table potential. Since the potential is undefined in this region, the simulation cannot progress.
------
Joshua A. Anderson, Ph.D.
Research Area Specialist, Chemical Engineering, University of Michigan
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