It's different, yes. But the trouble is that you need a controlled interrupt source--i.e., you have to have some concept of when an "event" might have been handled (were it not for such and such activity).
I posit that without that counterfactual talking about PREEMPTION is meaningless. The technique I mentioned--measuring and comparing the jitter was intended to quash measuring the performance of the network stack itself. Do you have an idea how you can pose that counterfactual in a synthetic arrangement more closely connected with the problem at hand? ... -Jon On Wed, 25 May 2005, Kris Kennaway wrote: > On Wed, May 25, 2005 at 03:33:39PM -0700, Jon Dama wrote: > > Could this be quantified by setting up a synthetic experiement: > > > > 1) one machine uses dummynet to generate a uniform packet/sec stream > > 2) another machine has a process receiving those packets and recording > > their arrival relative to the local TSC. afaik, the TSC is the only > > source of wall-time that doesn't involve a system call. Is that right? > > Are the TSCs synchronized on SMP systems? > > 3) Generate another source of activity on the receiving machine to > > estimate the effect of PREEMPTION relative to the (lack of) quiescence. > > 4) use the jitter in the TSC deltas to infer the effect of preemption > > That would be attempting to benchmark something entirely different. > > Kris > _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
