on 14/05/2011 18:25 John Baldwin said the following: > Hmmm, so this is not actually sufficient. NetApp ran into a very similar race > with virtual CPUs in BHyVe. In their case because virtual CPUs are threads > that > can be preempted, they have a chance at a longer race. > > The problem that they see is that even though the values have been updated, > the > next CPU to start a rendezvous can clear smp_rv_waiters[2] to zero before one > of > the other CPUs notices that it has finished.
As a follow up to my previous question. Have you noticed that in my patch no slave CPU actually waits/spins on smp_rv_waiters[2]? It's always only master CPU (and under smp_ipi_mtx). -- Andriy Gapon _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
