Re: [libvirt] [RFC][scale] new API for querying domains stats

1. Time to write() the RPC call to the socket 2. Time for libvirtd to process the RPC call 3. Time to recv() the RPC reply from the socket ...and so on.. If the time for item 2 dominates over the time for items 1 & 2 (which it should really) then the client thread is going to be sleeping in a poll() for the bulk of the duration of the libvirt API call. If we had an async API mechanism, then the VDSM time would essentially be consumed with 1. Time to write() the RPC call to the socket 2. Time to write() the RPC call to the socket 3. Time to write() the RPC call to the socket 4. Time to write() the RPC call to the socket 5. Time to write() the RPC call to the socket 6. Time to write() the RPC call to the socket 7. wait for replies to start arriving 8. Time to recv() the RPC reply from the socket 9. Time to recv() the RPC reply from the socket 10. Time to recv() the RPC reply from the socket 11. Time to recv() the RPC reply from the socket 12. Time to recv() the RPC reply from the socket 13. Time to recv() the RPC reply from the socket 14. Time to recv() the RPC reply from the socket