> That would certainly be a part of it, I'm sure they have stronger > fairness and guarantees at the expense of some performance. We saw the > spinlock starvation first on 8-16 core Opterons I think, wheras Altix > had been over 1024 cores and POWER7 1024 threads now apparently without > reported problems. I suppose P7 handles that in the HV through the pvcall. Altix AFAIK has special hardware for this in the interconnect, but as individual nodes get larger and have more cores you'll start seeing it there too. In general we now have the problem that with increasing core counts per socket each NUMA node can be a fairly large SMP by itself and several of the old SMP scalability problems that were fixed by having per node datastructures are back now. For example this is a serious problem with the zone locks in some workloads now on 8core+HT systems. > So I think actively enforcing fairness at the lock level would be > required. Something like if it is detected that a core is not making I suppose how that exactly works is IBM's secret sauce. Anyways as long as there are no reports I wouldn't worry about it. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
