PmeGpuProgramImpl Struct Reference

#include <gromacs/ewald/pme_gpu_program_impl.h>

Description

PME GPU persistent host program/kernel data, which should be initialized once for the whole execution.

Primary purpose of this is to not recompile GPU kernels for each OpenCL unit test, while the relevant GPU context (e.g. cl_context) instance persists. In CUDA, this just assigns the kernel function pointers. This also implicitly relies on the fact that reasonable share of the kernels are always used. If there were more template parameters, even smaller share of all possible kernels would be used.

Todo:

In future if we would need to react to either user input or auto-tuning to compile different kernels, then we might wish to revisit the number of kernels we pre-compile, and/or the management of their lifetime.

This also doesn't manage cuFFT/clFFT kernels, which depend on the PME grid dimensions.

TODO: pass cl_context to the constructor and not create it inside. See also Redmine #2522.

Public Types
using	PmeKernelHandle = void(*)(const struct PmeGpuCudaKernelParams)
	Conveniently all the PME kernels use the same single argument type.

Public Member Functions
	PmeGpuProgramImpl (const gmx_device_info_t *deviceInfo)
	Constructor for the given device.

Public Attributes
DeviceContext	context
	This is a handle to the GPU context, which is just a dummy in CUDA, but is created/destroyed by this class in OpenCL. TODO: Later we want to be able to own the context at a higher level and not here, but this class would still need the non-owning context handle to build the kernels.
size_t	warpSize
	Maximum synchronous GPU thread group execution width. "Warp" is a CUDA term which we end up reusing in OpenCL kernels as well. For CUDA, this is a static value that comes from gromacs/gpu_utils/cuda_arch_utils.cuh; for OpenCL, we have to query it dynamically.
size_t	spreadWorkGroupSize
	Spread/spline kernels are compiled only for order of 4. More...
PmeKernelHandle	splineKernel
PmeKernelHandle	splineKernelThPerAtom4
PmeKernelHandle	spreadKernel
PmeKernelHandle	spreadKernelThPerAtom4
PmeKernelHandle	splineAndSpreadKernel
PmeKernelHandle	splineAndSpreadKernelThPerAtom4
PmeKernelHandle	splineAndSpreadKernelWriteSplines
PmeKernelHandle	splineAndSpreadKernelWriteSplinesThPerAtom4
size_t	gatherWorkGroupSize
	Same for gather: hardcoded X/Y unwrap parameters, order of 4, plus it can either reduce with previous forces in the host buffer, or ignore them. More...
PmeKernelHandle	gatherReduceWithInputKernel
PmeKernelHandle	gatherReduceWithInputKernelThPerAtom4
PmeKernelHandle	gatherKernel
PmeKernelHandle	gatherKernelThPerAtom4
PmeKernelHandle	gatherReduceWithInputKernelReadSplines
PmeKernelHandle	gatherReduceWithInputKernelReadSplinesThPerAtom4
PmeKernelHandle	gatherKernelReadSplines
PmeKernelHandle	gatherKernelReadSplinesThPerAtom4
size_t	solveMaxWorkGroupSize
	Solve kernel doesn't care about the interpolation order, but can optionally compute energy and virial, and supports XYZ and YZX grid orderings.
PmeKernelHandle	solveYZXKernel
PmeKernelHandle	solveXYZKernel
PmeKernelHandle	solveYZXEnergyKernel
PmeKernelHandle	solveXYZEnergyKernel

Member Data Documentation

size_t PmeGpuProgramImpl::gatherWorkGroupSize

Same for gather: hardcoded X/Y unwrap parameters, order of 4, plus it can either reduce with previous forces in the host buffer, or ignore them.

Also similarly to the gather we can use either order(4) or order*order (16) threads per atom and either recalculate the splines or read the ones written by the spread

size_t PmeGpuProgramImpl::spreadWorkGroupSize

Spread/spline kernels are compiled only for order of 4.

There are multiple versions of each kernel, paramaretized according to Number of threads per atom. Using either order(4) or order*order (16) threads per atom is supported If the spline data is written in the spline/spread kernel and loaded in the gather or recalculated in the gather. Spreading kernels also have hardcoded X/Y indices wrapping parameters, as a placeholder for implementing 1/2D decomposition.

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The documentation for this struct was generated from the following files:

• src/gromacs/ewald/pme_gpu_program_impl.h
• src/gromacs/ewald/pme_gpu_program_impl.cpp
• src/gromacs/ewald/pme_gpu_program_impl_ocl.cpp