I honestly don’t know - will have to defer to Brian, who is likely out for at least the extended weekend. I’ll point this one to him when he returns.
> On Dec 22, 2017, at 1:08 PM, Brian Dobbins <bdobb...@gmail.com> wrote: > > > Hi Ralph, > > OK, that certainly makes sense - so the next question is, what prevents > binding memory to be local to particular cores? Is this possible in a > virtualized environment like AWS HVM instances? > > And does this apply only to dynamic allocations within an instance, or > static as well? I'm pretty unfamiliar with how the hypervisor (KVM-based, I > believe) maps out 'real' hardware, including memory, to particular instances. > We've seen some parts of the code (bandwidth heavy) run ~10x faster on > bare-metal hardware, though, presumably from memory locality, so it certainly > has a big impact. > > Thanks again, and merry Christmas! > - Brian > > > On Fri, Dec 22, 2017 at 1:53 PM, r...@open-mpi.org <mailto:r...@open-mpi.org> > <r...@open-mpi.org <mailto:r...@open-mpi.org>> wrote: > Actually, that message is telling you that binding to core is available, but > that we cannot bind memory to be local to that core. You can verify the > binding pattern by adding --report-bindings to your cmd line. > > >> On Dec 22, 2017, at 11:58 AM, Brian Dobbins <bdobb...@gmail.com >> <mailto:bdobb...@gmail.com>> wrote: >> >> >> Hi all, >> >> We're testing a model on AWS using C4/C5 nodes and some of our timers, in >> a part of the code with no communication, show really poor performance >> compared to native runs. We think this is because we're not binding to a >> core properly and thus not caching, and a quick 'mpirun --bind-to core >> hostname' does suggest issues with this on AWS: >> >> [bdobbins@head run]$ mpirun --bind-to core hostname >> -------------------------------------------------------------------------- >> WARNING: a request was made to bind a process. While the system >> supports binding the process itself, at least one node does NOT >> support binding memory to the process location. >> >> Node: head >> >> Open MPI uses the "hwloc" library to perform process and memory >> binding. This error message means that hwloc has indicated that >> processor binding support is not available on this machine. >> >> (It also happens on compute nodes, and with real executables.) >> >> Does anyone know how to enforce binding to cores on AWS instances? Any >> insight would be great. >> >> Thanks, >> - Brian >> _______________________________________________ >> users mailing list >> users@lists.open-mpi.org <mailto:users@lists.open-mpi.org> >> https://lists.open-mpi.org/mailman/listinfo/users >> <https://lists.open-mpi.org/mailman/listinfo/users> > > _______________________________________________ > users mailing list > users@lists.open-mpi.org <mailto:users@lists.open-mpi.org> > https://lists.open-mpi.org/mailman/listinfo/users > <https://lists.open-mpi.org/mailman/listinfo/users> > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://lists.open-mpi.org/mailman/listinfo/users
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