Saturday, December 17, 2016

Hybrid Parallelism Approaches for CFD

This previous post, Plenty of Room at Exascale, focuses on one specific commercial approach to scaling CFD to large problems on heterogeneous hardware (CPU & GPU) clusters. Here's some more references I found interesting reading on this sort of approach.

Strategies

Recent progress and challenges in exploiting graphics processors in computational fluid dynamics provides some general strategies for using multiple levels of parallelism accross GPUs, CPU cores and cluster nodes based on that review of the literature:
  • Global memory should be arranged to coalesce read/write requests, which can improve performance by an order of magnitude (theoretically, up to 32 times: the number of threads in a warp)
  • Shared memory should be used for global reduction operations (e.g., summing up residual values, finding maximum values) such that only one value per block needs to be returned
  • Use asynchronous memory transfer, as shown by Phillips et al. and DeLeon et al. when parallelizing solvers across multiple GPUs, to limit the idle time of either the CPU or GPU.
  • Minimize slow CPU-GPU communication during a simulation by performing all possible calculations on the GPU.

Wednesday, July 6, 2016

Exciting 3D Print Service Developments

It has never been easier to go from a design in your head to parts in your hand. The barriers to entry are low on the front end. There are all sorts of free and open source drawing, mesh editing, modeling or CAD applications. On the fabrication end of things, services like shapeways, and imaterialise continue to improve their delivery times, material options and prices.

One of the recent developments that deserves some attention is in metal 3D printing. imaterialise has offered parts in DMLS titanium for a while, but they've been pretty pricey. They have now significantly reduced the prices on Ti parts, and are now offering a trial with aluminum. Not to be left out, Shapeways has graduated SLM aluminum from its pilot program.

It's great to see such thriving competition in this space. I'm working on some models specifically for this metal powder-bed fusion technology. What will you print?