Dear all,

I have some troubles trying to specify a computational grid with moving windows using picongpu v0.2.0. We were discussing this topic previously, however I have the same problem again, so likely I misunderstand something from the last time.

So I'm trying to launch the simulation using 4 K80 cards: 8 GPU devices overall. In the memory.param file I have specified the SuperCell layout as (2,8,2). I want to have one GPU in transversal direction and 8 in longitudinal. So in cfg file I specified:

TBG_gpu_x=1

TBG_gpu_y=8

TBG_gpu_z=1

Then I would like my real computational domain to have 256 x 3712 x 256 cell. Since the moving window reduces the real domain by 1 GPU in y direction, I specified my grid as 256 x 4176 x 256. (4176 = 9/8*3712)

TBG_gridSize="-g 256 4176 256"

However, trying to submit such a cfg file I'm receiving an assertion fail:

void picongpu::MySimulation::checkGridConfiguration(PMacc::DataSpace<DIM>,PMacc::GridLayout<DIM>) [with unsigned int DIM = 3u]: Assertion`gridSizeLocal[i] % MappingDesc::SuperCellSize::toRT()[i] == 0' failed.

However 4176 % 8 == 0 and 256 % 2 == 0. 

Could you please guide me how to solve this issue? Looks like I misunderstand the concept of the SuperCell.

Thank you in advance,

Danila.