Comment (by Roland Haas):

My only suggestion would be to make sure that the different threads are not all tied to the same CPU core. The Marenostrum docs may have examples for this. You could also try and see if adding

ActiveThorns = SystemTopology

would help since it will forcefully adjust the thread binding at runtime.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2882/running-bbh-with-carpetx-with-cpus-high