On Fri, Nov 12, 2010 at 11:54 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > On Nov 11, 2010, at 6:15 PM, Matthew Knepley wrote: > > > On Fri, Nov 12, 2010 at 9:52 AM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > > > What should we use a for programming model for PETSc on multi-core > systems? Currently for conventional multicore we have only have one MPI > process per core and for GPU we have subclasses of Vec and Mat with custom > CUDA code. > > > > Should we introduce subclasses of Vec and Mat built on pthreads (this > is what Bill G recommends, and not to use OpenMP)? > > > > pthreads are a nightmare and do not do vectorization right, which is > necessary here. > > What do you mean do not vectorize? I mean its easy to tell a thread to do something, but I was not aware that pthreads had nice support for telling all threads to do something at the same time. On a multicore, you want vector instructions, and on a GPU you basically have no choice. > > I am for OpenCL/CUDA. Eventually > > I think OpenCL will take its head out of its ass and be as nice as CUDA. > > That's fine for GPUs but what about 8 core or 12 core Intel processors? > CUDA for that also? OpenCL already runs on these, but the interface is too low-level. It should look more like CUDA. In CUDA, you have constructs for vectorization, but you can also branch as Jed indicated. This is slow on a GPU, but would be fine on a multicore. Jed, do you see obvious shortcomings of CUDA for these multicore machines? Matt > > Barry > > > > > Matt > > > > Is there a way to have some kind of consistent model between > conventional multicore and GPU multi-core? If not the same code. What about > this MCUDA stuff? > > > > Barry > > -- > > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > > -- Norbert Wiener > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20101112/b6c70b2c/attachment.html>