Anthony Liguori wrote: > I don't think it's established that PV/VF will have less latency than > using virtio-net. virtio-net requires a world switch to send a group > of packets. The cost of this (if it stays in kernel) is only a few > thousand cycles on the most modern processors. > > Using VT-d means that for every DMA fetch that misses in the IOTLB, > you potentially have to do four memory fetches to main memory. There > will be additional packet latency using VT-d compared to native, it's > just not known how much at this time.
If the IOTLB has intermediate TLB entries like the processor, we're talking just one or two fetches. That's a lot less than the cacheline bouncing that virtio and kvm interrupt injection incur right now. -- error compiling committee.c: too many arguments to function _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
