Uwe Klein wrote: > Kevin Oberman wrote: >> To get an idea of the fanaticism involved, several years ago, Kirk >> McKusick and my former boss here in Berkeley counted the machine cycles >> in the FreeBSD kernel for the PPS response(all done in the interrupt >> service routine) and used that to correct the time. Of course,in the >> days of 16 and 40 MHz systems, this was a bit more important. > > Determinism has been lost. > > Cache hits/misses, abitrated bus accesses, multicore contention, ... > All have cost determinism in latency. You can count cycles > but wont see the same count ever.
Which is one of the reasons the short pipeline and in-order Pentium made some pretty nice ntp servers. This is coming back you know, in the form of Atom and Larrabee cpus: Many in-order cores with much more deterministic performance. Terje Terje -- - <Terje.Mathisen at tmsw.no> "almost all programming can be viewed as an exercise in caching" _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
