To-Do List

3/14/2012

• try nvvp/transpose (or C60 with more grid points) for >5 minutes (lli2010)
• send mail to nvidia or list to understand why nvvp profile cuts off after 5 minutes (lli2010)
• understand bottleneck in get_wfs (jun)
• think about eliminating gemv in paw (jun)
• implement fft (cpo)
• is there a cuda library for trace like zgeev (cpo)
• run a 3x3x3 system to see if bottlenecks stay the same (cpo)
• understand gs.py bottlenecks in more detail (lin/cpo) using gpaw profiler

General Topics

• Stanford CUDA course: http://code.google.com/p/stanford-cs193g-sp2010/
• (Everyone) Understand gpaw (read paper)
  • what other steps could we parallelize?
  • Can we do existing parallelization better? (e.g. use ideas in Todd's GPU papers)
• (Everyone) Go through CUDA tutorial here.
  • Understand blocks/threads/warps and how they map onto GPU hardware (details of which can be seen with "deviceQuery" command)
• (Lin) Find tool to measure:
  • memory bandwidth usage
  • gpu flops usage
• (Jun) :
  • Parallelize LCAO/planewave/RPA (zher performance?)? non-rmm-diis eigensolver?
  • merge with trunk?
• (cpo) :
  • Understand code flow
  • Understand where the ~23 cuda kernels are used
  • Understand which bottlenecks we need to tackle
• Do another gpu-gpaw install (to learn)
• Understand Pt 3x4x3 CPU/GPU difference versus 3x2x3 (performance scaling with system size)
• Can multiple CPU processes win by using the same GPU?
• Understand pycuda
• Understand gpaw interface to cuda (c/cuda subdirectory)
• Read CUDA programming manual here.
• Do all gpaw self-tests pass with GPUs?
• Can we get bigger bang-per-buck with GeForce instead of Tesla? (don’t need GPUDirect, maybe live with less memory/bandwidth? double precision worse)
• Understand cuda better:
  • Does Samuli use pinned memory correctly?
  • run/understand cuda a bandwidth benchmark
  • Could we use GPUdirect for MPI data transfer?
• Does the GPU performance scale with the product of gridpoints*bands? Might be a combinatorial effect with the bands, linear with the grid points?
• Duplicate Samuli results
• Update to most recent version in svn
• Understand where gpaw scaling maxes out for Pt 3x4x3
• Why is CO on 2 GPUs slower than on 8 CPUs?
• Can we do something less precise in the vacuum area? (fewer grid points?)
• Do we need a fatter interconnect for GPUs?