On Tue, Nov 26, 2013 at 12:21:40PM +0100, Ingo Molnar wrote: > I'm somewhat reluctant to chalk it up to a single mfence - maybe > timings/behavior changed in some substantial way?
Ah indeed! We also changed the case where an enqueueing futex sees the uval change and bails. It is now far more expensive due to having to both queue and unqueue, whereas before it wouldn't queue at all. I suppose the idea was to offset that by not requiring locking on the wake side. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
