Hi, Am 15.03.2016 um 20:43 schrieb Lane, William:
> I'm just curious about what the current thoughts are WRT hyperthreading. > > I've read at least one article that suggested hyperthreading be left on so > that > the OS can take advantage of it, but that hyperthreading cores should be > excluded > from being bound to SoGE HPC jobs. Is this still the best strategy to follow? > Or > was it ever a good strategy to follow? > > Could excluding hyperthreading cores be accomplished by using the qsub > -binding > parameter? Or should SoGE itself be configured to ignore hyperthreading cores? > > My research into hyperthreaing and HPC has only turned up two strategies: > 1. turn off hyperthreading completely at the BIOS level > 2. the above situation where the OS is still allowed to use hyperthreading > but HPC > apps are disallowed binding to hyperthreading cores. I came to the same conclusion, as our applications don't like HT. I don't recall whether it was on the Beowulf or Open MPI list, where someone mentioned that turning HT off in the BIOS will also make some changes to the internal caching and/or handling of the pipeline. But I couldn't see this effect (I would have expected to get only half of the cores but slightly faster). HT may be better suited in case you want to run at least two different jobs on a machine and the access to CPU resources can joggle this way. I mean: using HT for an Open MPI or OpenMP job on a machine will lead to the effect that all forks/threads are doing the same at the same time and need the same resources (at least I would expect it to be this way). But two completely unrelated types of jobs may have better luck to get a benefit of HT. Looking into new machines, there are also several CPUs without HT capability. -- Reuti _______________________________________________ users mailing list users@gridengine.org https://gridengine.org/mailman/listinfo/users
