On 26/02/14 15:14, Waiman Long wrote: > Locking is always an issue in a virtualized environment as the virtual > CPU that is waiting on a lock may get scheduled out and hence block > any progress in lock acquisition even when the lock has been freed. > > One solution to this problem is to allow unfair lock in a > para-virtualized environment. In this case, a new lock acquirer can > come and steal the lock if the next-in-line CPU to get the lock is > scheduled out. Unfair lock in a native environment is generally not a > good idea as there is a possibility of lock starvation for a heavily > contended lock. I'm not sure I'm keen on losing the fairness in PV environment. I'm concerned that on an over-committed host, the lock starvation problem will be particularly bad. But I'll have to revist this once a non-broken PV qspinlock implementation exists (or someone explains how the proposed one works). David _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
