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
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