On Thu, 28 Jan 2010 09:12:23 am Michael S. Tsirkin wrote: > virtio is communicating with a virtual "device" that actually runs on > another host processor. Thus SMP barriers can be used to control > memory access ordering. > > Where possible, we should use SMP barriers which are more lightweight than > mandatory barriers, because mandatory barriers also control MMIO effects on > accesses through relaxed memory I/O windows (which virtio does not use) > (compare specifically smp_rmb and rmb on x86_64).
Xen had a similar issue, in that UP guests running on SMP hosts need to issue SMP barriers. Is this not also a requirement for virtio? But I'm not sure what came out of the discussion: Jeremy? Cheers, Rusty. _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
