On Jan 5, 2013, at 3:33 AM, Ole Holm Nielsen <[email protected]> wrote:
> > On 04-01-2013 18:28, Ralph Castain wrote: >> FWIW: I believe we have a mapper in Open MPI that does what you want - i.e., >> it looks at the number of available cpus on each node, and maps the >> processes to maximize the number of procs co-located on nodes. In your >> described case, it would tend to favor the 16ppn nodes as that would provide >> the best MPI performance, then move to the 8ppn nodes, etc. > > Yes, OpenMPI can be tweaked into different task layouts on the available set > of > nodes. But the problem at hand is for the scheduler to allocate some set of > nodes, given that the user want a specific number of MPI tasks (say, 32), and > given that there are heterogeneous nodes available with 4, 8 or 16 cores. As > Moe wrote, this flexibility would be hard to achieve with Slurm (with Maui > it's > impossible). I think you may have misunderstood both Moe and I. I believe Moe was pointing out that you would need a new plugin to provide that capability, and I pointed out that we already have that algorithm in OMPI and could port it to a Slurm plugin if desired. That said, it would take some time to make that happen, so it may not resolve your problem. > > Regards, > Ole
