Xbox 360: Anyone confirm if this is true
- Thread starter pakpassion
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Alstrong said:easy there hardcore coder extreme
What do you think is an efficent use of three cores then?
Depends on the game, but you really need to break things down and start to look at data dependencies, you move your game to become a series of smaller tasks with minimal interdependency. You can then just farm out the smaller jobs to threads as they are free.
Unfortunately breaking things down into a large enough number of small enough pieces that are not interdependant requires a MASSIVE amount of work, and it's unlikely you can even move there incrementally. You have to loose (or at least minimise) the concept of r/w global state to do it right.
In the short term you'll likely see games running predominantly single threaded, exploiting trivial parallelism (like the stuff I outlined above) and then adding "jobs" to make things prettier and use up the CPU time, cloth simulation, hair, fluid, all the trivially parallel stuff.
I think the interesting stuff is dedicating the resources to the core gameplay stuff, but it's much harder.
Hardknock said:
funny, about 1 hour ago i was chatting to a xbox360 near-launch title* developer right after a short presentation by him in front of 150 developers explaining how his team were using the xbox cores in an efficient way. ..so the developer was a lying sob, apparently. gotta give him a call and tell him that right in his face..
* technically a next spring title, but i'd say maybe the most playable one on the show floor, together with kameo. the pgr3 build they had there oth shouldn't 've been shown at all.
It's not an argument in logic, but a question on utilization, and code efficiency, which only the developer can answer here, and you guys can't. I should have worded things better, as I see I was not very clear, and the examples I gave were abitrary, and not related to what I think of Call of Duty 2, which looks very good.
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Bizarre Creations has said that they are using all cores for PGR3, even their "mini game" Geometry Wars : Retro Evolved is using mutiple cores because they have to simulate/calculate 60,000 points on the game's gravity grid.
http://www.bizarreonline.net/index.php?action=fullnews&showcomments=1&id=64
Just because they're using all cores doesn't mean they are used fully. The main game probably runs for the most part on one core. I bet you could probably still play the game without sound and Live/Dashboard intergration on only one core. I wish they gave us more insight into the physics of the game because that's what is most interesting to me.
http://www.bizarreonline.net/index.php?action=fullnews&showcomments=1&id=64
Just because they're using all cores doesn't mean they are used fully. The main game probably runs for the most part on one core. I bet you could probably still play the game without sound and Live/Dashboard intergration on only one core. I wish they gave us more insight into the physics of the game because that's what is most interesting to me.
Per definition, a thread can only (concurrently) execute on a single processor (and then only on one of the two hardware threads). The scheduler can move threads from core to core, but that is — if it happens often — a bad idea (L1 caches are unnecessarily polluted, L2 is shared, so that shouldn't matter).Alstrong said:Do you mean using multiple processors to work on one thread
What people or talking about (I reckon) is breaking down a single sub-system / problem into easily parallelizable (warning — word invention at work!) chunks (e.g. computing cloth physics for a character; if there's more than one character, then two threads can compute "physics" at the same time: one for each character) and then processing these independent chunks in parallel.
This is what many would call "low-hanging fruit" optimisation. To get to the size of work-units ERP mentions, is a completely different matter (and much harder).
BriefcasemanX
Newcomer
Edge said:
i think you mean 200%
I think this is part of the problem in understanding distribution of workload, as the term 'thread' has more than one meaning, even if one of those isn't official (and I don't know if it is or not). A game could be broken into several conceptual 'threads' (subsytem or problem as you term it) such as physics, gameloop, AI and audio. Each of these 'threads' is then dealt with. As you found, you felt a need to make up words to satisfy the explanation because there's apparently no commonly known terminology. Hence 'thread' is used to referrence to difference aspects of programming.[maven] said:
mckmas8808
Legend
one said:
Again INQ proves that they are the jokes of the internet. Yet people here still give them so much credit for no reason at all.
mckmas8808 said:
Did you even read it?
Actually the article was pretty good, and shows they have no problems correcting a previous story. Plus they gave the low-down on the Xbox 360 kiosks(with some looking like crap due to being incorrectly setup.) And even have quotes from developers about multi-threading. Although I know they can be wrong sometimes, this article in particular is very on point.
Alstrong said:Thank you for your thoughts on the matter, ERP
Do you mean using multiple processors to work on one thread
No I just mean multiple cores working on the core simulation. We dedicate a small percentage of one slow processor to this in most games today, but the way I think games will develop, I think that is going to change.
How about GTA3 (using it purely as an example) with a persisitent population, where what you do in the world can have a permanent impact.... Hold a guy up in the street and he remembers you, decimate an entire neighborhood and it might become a slum.
I don't know if we'll get there this gen, but the concept of an environment you can play in (and with) aswell as have traditional gameplay experiences in is very compelling, at least to me.
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