Erik Hofman writes: > Martin Spott wrote: > > I'm about to purchase a used 8-way RS/6000. Coltish as I am I'd like to run > > FlightGear on this machine. This won't work out as long as most of the > > processing in FlightGear is done in a single thread because each of the > > CPU's is not that fast. > > Things that come in mind are: > > * Sound thread (should be fairly easy) > * FDM thread/process > * Maybe (just maybe) an I/O thread? > > But I guess that's about it.
Personally, I'm not a huge fan of threading unless absolutely necessary. Threading adds a tremendous amount of complexity, it can hide extremely subtle bugs that are extremely difficult to track down and only show up under rare circumstances. I saw a lot of nifty looking examples of threading in school, but once you hit an application with the complexities of FlightGear, you have to be *really* careful, and *really* know what you are doing, or you end up making a *really* big mess. That is a pretty hefty price to pay. We put in a *huge* amount of work into the threaded tile pager and I spent many, many evenings staring at code, scratching my head, running flightgear for hours trying to track down subtle, rare gotchas. Think about this another way ... do a profile of flightgear. I bet you will find that the graphics rendering portion of FlightGear takes 90-95% of the entire application work load. If you can't find a way to split that up (which is nigh unto impossible since this is all involving opengl which inherently resists threading without a *huge* amount of effort and complexity[1]) then threading the other 5-10% of the work isn't going to gain you a whole lot. [1] The Performer scene graph has app-cull-draw threads, but you pay the price with an very large amount of complexity, bloat, and some performance loss for single CPU machines. On a single CPU machine, plib will almost always render the same model faster than performer. Curt. -- Curtis Olson IVLab / HumanFIRST Program FlightGear Project Twin Cities curt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
