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Ascended_Saiyan3 on 15 April 2009
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Deneidez said:
Ascended_Saiyan3 said:
Deneidez said:
Ascended_Saiyan3 said:

Why would you use extremely branchy code when ALL processors run MUCH faster without them (Branch Elimination). Anyway, the Cell has branch hinting. If you know what you're doing, there would be FAR less penalties for a branch miss on the Cell. Plus, you are wrong about your statement saying most general purpose processors would rape Cell in general purpose tasks AS MY DOZEN OR SO LINKS PROVE (one or two pages back). There's that blind eye, again. ;)

Branch predicting != OoOE and sometimes you have to have lots of branches, if theres enough branches in program even old Xbox would perform better than CELL. Theres also problems with memory in CELL approach. SPEs have way too small memory for some tasks. For example 50MB chunk in memory with random depencies into other points of that 50MB chunk. You would have to use main mem only and that would make processing quite slow.

And about that blind eye. Show me one link that shows that its better in general purpose stuff than PCs today. If you run only simple instructions/integer stuff, CELL wouldn't beat even 3-4 years old average computers and if you put some branches there it would render even slower.

Well, as there seem to be title war. I am going to be master of science in computer science in year or two.

(Btw, first program is available. For linux & windows. Check sig, ty. ^^)

That's not true, IF the programmer use the branch hints PROPERLY.  If they don't, you would be right.  However, that would be the programmer's fault and not the processor, because the processor is capable with proper effort.

Don't ask me to provide the links AGAIN, when I went through the trouble of putting them all in one place (one to two pages back).  Just look at the multiple purposes (by definition that's general) that were demonstrated.

What's this about a title war?  BTW, Mike Acton, from Insomniac, tells you to UNlearn what they taught you in school.  He says the UNlearning process is what makes parallelizing your code for the Cell hard.  Have you UNlearned your old practices today? ;)

You cannot predict all branches. Well, I checked those links are there were only mention that CELL can do general processing, but there were nothing about how good it is in it. Other than some marketing speech of course.

Well, not title war. More like title boasting. :)

Anyway same applies for X360 too,

http://arstechnica.com/old/content/2005/06/xbox360-2.ars/7

Rumors and some game developer comments (on the record and off the record) have Xenon's performance on branch-intensive game control, AI, and physics code as ranging from mediocre to downright bad. Xenon will be a streaming media monster, but the parts of the game engine that have to do with making the game fun to play (and not just pretty to look at) are probably going to suffer. Even if the PPE's branch prediction is significantly better than I think it is, the relatively meager 1MB L2 cache that the game control, AI, and physics code will have to share with procedural synthesis and other graphics code will ensure that programmers have a hard time getting good performance out of non-graphics parts of the game.

...

At any rate, Playstation 3 fanboys shouldn't get all flush over the idea that the Xenon will struggle on non-graphics code. However bad off Xenon will be in that department, the PS3's Cell will probably be worse. The Cell has only one PPE to the Xenon's three, which means that developers will have to cram all their game control, AI, and physics code into at most two threads that are sharing a very narrow execution core with no instruction window. (Don't bother suggesting that the PS3 can use its SPEs for branch-intensive code, because the SPEs lack branch prediction entirely.)

etc. Read the whole article.

Better Performance Through Branch Elimination - by Mike Acton (Insomniac)

I know why you are trying to ignore my previous statement about branch hints on the Cell.  It's that blind eye thing, again.

BTW, thanks for providing an article from 2005 (I read it in 2006), when these people had hardly ANY idea of how to do things on the Cell.  NOW, we should ALL know that the Cell is better for A.I. than Xenon.  It's been demonstrated.  Like I said, branch hints have a MUCH lower penalty for a missed branch and branch elimination performs MUCH MUCH better on the Cell than Xenon.