This video is mostly a more organized version of things I said throughout the last console generation. I guess I wanted to give the PS3 a proper send-off by gathering all these points into one video.
I had another whole section in here talking about multi-threading, but it made the video LONG and I don’t think it was needed. (Although at one point I say, “You’ve probably guessed that the big hurdle here is the need for lots of parallel coding.” That doesn’t make total sense to expect non-coders to “guess” anything without the long rambling section on multi-threading.)
Another thing I didn’t get into is the idea of processing latency. As I read it, your program gives tasks to the PPE and it delegates to the SPE. If your program is really parallel friendly then the PPE ought to be able to keep all the little SPEs busy all the time. However, this introduces a middleman to the process. Even assuming you can keep all the little sub-processors busy, you’ve still got this annoying lag.
Let’s say you’re trying to send a package. One courier uses a bike. He can take one box across the city in a day. The other outfit has a van that can take ten packages across the city, but they spend some time sorting packages at the distributions center or whatever. They deliver in two days.
The van has higher throughput: Ten packages in two days instead of one package in one day. But sometimes you don’t want to wait two freakin’ days. So arguments over which one is “faster” are kind of confused. It sort of depends on what you’re trying to send and when you need it.
More importantly, processing latency is really bad for games. It’s fine for rendering farms and crunching primes, but in a videogame latency matters. I don’t care if a game has mega graphics at 200 frames a second, if it takes five seconds between the point where I hit the jump button and the moment when I see my character jump on screen, then this computer is not useful for gaming. Obviously the PS3 wasn’t that bad, but the processing latency is yet another unwanted thing coders might have to worry about. I didn’t bring this up in the video because I have no idea how bad this problem was.
I am really glad these next-gen machines have settled into more or less standard quasi-PC hardware. This ought to make them nice and cheap over time, and should make cross-platform work less of a headache.
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