Avi Kivity <avi@xxxxxxxxxx> wrote: > On 06/08/2012 01:16 PM, Juan Quintela wrote: >> Anthony Liguori <aliguori@xxxxxxxxxx> wrote: >> >> Once told that, we need to measure what is the time of an async page >> fault over the network. If it is too high, post copy just don't work. >> >> And no, I haven't seen any measurement that told us that this is going >> to be fast enough, but there is always hope. > > At 10Gb/sec, the time to transfer one page is 4 microseconds. At > 40Gb/sec this drops to a microsecond, plus the latency. This is on par > with the time to handle a write protection fault that precopy uses. But > this can *only* be achieved with RDMA, otherwise the overhead of > messaging and copying will dominate. > > Note this does not mean we should postpone merging until RDMA support is > ready. However we need to make sure the kernel interface is RDMA friendly. Fully agree here. I always thought that postcopy will work with RDMA or something like that, any other thing would just add too much latency. Later, Juan. -- 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
