> Therefore for a set of "conforming" SMP systems which don't > have the listed 3 issues, we provide a feasible solution. > I don't see how we can avoid this - unless we don't care about > getting time right. Interesting. I guess you only need to get time "right enough" - there's an unavoidable fuzziness about the synchronisation of events on different CPUs (corresponding to the uncertainties of the timing of any rendezvous between them). A naive network synchronisation protocol - analogous to your first proposal - would leave clocks differing by a network round-trip time or so: but NTP does a lot better. So in principle you should be able to scale NTP to create a clock synchronised within some fraction of the time taken by a CPU-to-CPU communication... but compressing the essence of the NTP protocol into something which runs fast enough might be interesting! My 5-minutes-over-breakfast feeling is that you should be able to figure out a way to get time right enough; try reading up how NTP works and see whether it can be made to work? -- Dominic
