Re: [OMPI users] what was the rationale behind rank mapping by socket?

"r...@open-mpi.org" writes: > Yes, I’ve been hearing a growing number of complaints about cgroups for that > reason. Our mapping/ranking/binding options will work with the cgroup > envelope, but it generally winds up with a result that isn’t what the user > wanted or

Re: [OMPI users] what was the rationale behind rank mapping by socket?

Thanks, Ralph, A video would be great to accompany the slides! I hope you have a good and productive SC16. -- bennet On Fri, Oct 28, 2016 at 8:40 PM, r...@open-mpi.org wrote: > Yes, I’ve been hearing a growing number of complaints about cgroups for that > reason. Our

Re: [OMPI users] what was the rationale behind rank mapping by socket?

Yes, I’ve been hearing a growing number of complaints about cgroups for that reason. Our mapping/ranking/binding options will work with the cgroup envelope, but it generally winds up with a result that isn’t what the user wanted or expected. We always post the OMPI BoF slides on our web site,

Re: [OMPI users] what was the rationale behind rank mapping by socket?

Ralph, Alas, I will not be at SC16. I would like to hear and/or see what you present, so if it gets made available in alternate format, I'd appreciated know where and how to get it. I am more and more coming to think that our cluster configuration is essentially designed to frustrated MPI

Re: [OMPI users] what was the rationale behind rank mapping by socket?

FWIW: I’ll be presenting “Mapping, Ranking, and Binding - Oh My!” at the OMPI BoF meeting at SC’16, for those who can attend. Will try to explain the rationale as well as the mechanics of the options > On Oct 11, 2016, at 8:09 AM, Dave Love wrote: > > Gilles

Re: [OMPI users] what was the rationale behind rank mapping by socket?

Gilles Gouaillardet writes: > Bennet, > > > my guess is mapping/binding to sockets was deemed the best compromise > from an > > "out of the box" performance point of view. > > > iirc, we did fix some bugs that occured when running under asymmetric > cpusets/cgroups. > > if you

Re: [OMPI users] what was the rationale behind rank mapping by socket?

Bennet, my guess is mapping/binding to sockets was deemed the best compromise from an "out of the box" performance point of view. iirc, we did fix some bugs that occured when running under asymmetric cpusets/cgroups. if you still have some issues with the latest Open MPI version (2.0.1)

Re: [OMPI users] what was the rationale behind rank mapping by socket?

Pardon my naivete, but why is bind-to-none not the default, and if the user wants to specify something, they can then get into trouble knowingly? We have had all manner of problems with binding when using cpusets/cgroups. -- bennet On Thu, Sep 29, 2016 at 9:52 PM, Gilles Gouaillardet

Re: [OMPI users] what was the rationale behind rank mapping by socket?

David, i guess you would have expected the default mapping/binding scheme is core instead of sockets iirc, we decided *not* to bind to cores by default because it is "safer" if you simply OMP_NUM_THREADS=8 mpirun -np 2 a.out then, a default mapping/binding scheme by core means the OpenMP

[OMPI users] what was the rationale behind rank mapping by socket?

Hello All, Would anyone know why the default mapping scheme is socket for jobs with more than 2 ranks? Would they be able to please take some time and explain the reasoning? Please note I am not railing against the decision, but rather trying to gather as much information about it as I can