If you don't want handwaving, I'd just test it. There are jobs that do work with HT, and those that don't.
From the tests I've done it's not particularly reliable. So the performance you get depends on what else the CPU is doing. So if you have jobs A and B on a single CPU with 2 HT threads the performance of A and B vary depending on the phase of the moon. So if jobs A and B use 16 CPUs and have to make progress in lock step (common in parallel jobs) you get the worst case of
16 CPUs, which is VERY likely to be less than turning HT off. I have seen occasional improvements in throughput of 5-10% or so. So without testing I'd vote turn it off. The best benchmark is your code. _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
