[Wylug-help] Linux & hyperthreading

[linux@kepier.clara.net]

Hi all,

Could anyone offer any advice on how well linux deals with
hyperthreading? I've been reading some notes which suggest that
enabling hyperthreading in the kernel might not be necessarily so
beneficial, but it could be more helpful if individual applications are
compiled to support it. This is for fp calculations.

I've just been testing an openmosix cluster of dual-p4 nodes. I'm
having a problem, that some nodes acquire (through process migration)
up to three, or even maybe four, of equivalent high-cpu jobs - rather
than spreading those extra jobs into other unused nodes. Someone on the
openmosix mailing list has mentioned that they see the same problem,
and that they disable hyperthreading in the kernel to get around this.
However I'm not sure that I can persuade the cluster admin that not
having hyperthreading would be a good thing - even though, as I
understand it, individual applications compiled with ht support would
still get the benefits of ht.

Does anyone have any ideas on this?

Thanks,

--
Neil