Bill Galbraith wrote: > > > > >>-----Original Message----- >>From: [EMAIL PROTECTED] >>[mailto:[EMAIL PROTECTED] On >>Behalf Of Stefan Seifert >>Sent: Saturday, May 12, 2007 10:38 PM >>To: FlightGear developers discussions >>Subject: Re: [Flightgear-devel] More ideas on dogfighting >> >>-----BEGIN PGP SIGNED MESSAGE----- >>Hash: SHA1 >> >>James Palmer wrote: >> >> >> >>>In your experience, Harald, what has been the approximate >>> >>> >>ratio of FDM >> >> >>>vs Graphics vs remainder code on CPU time? Has anyone done work on >>>clocking the various subroutines in FG to determine this? >>> >>> >>(Perhaps I >> >> >>>underestimate the CPU time required of the FDM?) >>> >>> >>You could simply run stand-alone JSBSim >>(http://www.jsbsim.org) to see, how much CPU a FDM needs. I'd >>guess that Yasim lies in the same range. >> >>Nine >> >> > > >I think that was investigated a few months ago. JSBSim FDM took only a >couple percent of the CPU, or course depending on your hardware and what you >were drawing. I don't think it's anything that you need to worry about. > >BIll > > > I don't have fresh number but the time of a standalone JSBSim takes has nothing to do with the time the FDM takes in FG. First it depends on how many times you run it per second (in FG the default is 120 Hz). Second in addition to the fdm itself we are computing some ground intersection. And since the world geometry is very badly organized in FG this can take some non negligeable time (but we should see a great improvment in the intersection code with the osg branch). Now if the server is doing the FDM computation it's obvious that there is no need to do that 120 times per second because the data can not be send at that rate. How many loops does the mp server need to do per second ? 10 ? 20 ? At that frequency you could handle 100 clients with no problems.
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