#1850: Severe performance problem on Stampede -------------------------+-------------------------------------------------- Reporter: hinder | Owner: Type: defect | Status: confirmed Priority: major | Milestone: Component: SimFactory | Version: development version Resolution: | Keywords: -------------------------+--------------------------------------------------
Comment (by rhaas):
The issue is sometimes that there are things that run before SystemTopology and hwloc have had a chance to set affinity, eg MPI_INIT which itself may for example allocate memory which is then bound to the "wrong" core. If I remember correctly, then there is a ticket/email thread somewhere in which Erik suggests adding a pre-MPI_INIT hook to the flesh so that SystemTopology can set affinity early. Note that this has to happen (as the thread explains) before parameter files are parsed since one cannot access argv before MPI_INIT so in particular it will ignore ActiveThorns settings in parfiles.