On Fri, Feb 21, 2020 at 4:51 PM Junchao Zhang via petsc-dev < petsc-dev@mcs.anl.gov> wrote:
> Hello, > > I want to evaluate MatMult on GPU. I took a 2M x 2M matrix and ran with 6 > mpi ranks and 6 GPUs. It took about 0.9 seconds. A kernel launch or a > stream synchronization took about 10us. > Your call, but you should run the code once and then run it in a new timer. I've seen some big "warm up costs" GPUs today. > Compared with MatMult, they are tiny. Does it mean we can ignore them? > What is a proper size to evaluate MatMult? > It depends on the purpose/audience for the study. There is no right size other than being much larger than the launch cost, perhaps. > I heard it is a few thousand rows per MPI rank. Why? > Thanks. > --Junchao Zhang >
