On Fri, Oct 16, 2009 at 03:28:36PM -0400, Glauber Costa wrote: > When we migrate a kvm guest that uses pvclock between two hosts, we may > suffer a large skew. This is because there can be significant differences > between the monotonic clock of the hosts involved. When a new host with > a much larger monotonic time starts running the guest, the view of time > will be significantly impacted. > > Situation is much worse when we do the opposite, and migrate to a host with > a smaller monotonic clock. > > This proposed ioctl will allow userspace to inform us what is the monotonic > clock value in the source host, so we can keep the time skew short, and > more importantly, never goes backwards. Userspace may also need to trigger > the current data, since from the first migration onwards, it won't be > reflected by a simple call to clock_gettime() anymore. > > [ v2: uses a struct with a padding ] > [ v3: provide an ioctl to get clock data too ] > [ v4: used fixed-width signed type for delta ] > [ v5: nitpick fixes, documentation update, and capability bit ] > > Signed-off-by: Glauber Costa <glommer@xxxxxxxxxx> Applied, thanks (the ioctl number changed though). -- 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
