Altivec - how much faster is it?

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by jahc on 2003/3/1 21:23:20

Does anyone know how much faster altivec enabled programs are on a G4, than non-altivec programs? Like, 40% faster or what?

Lightwave raytrace test is 15% faster on G4 vs a G3 of the same speed, that should be mostly an Altivec delta.
     -Tig

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by Hattig on 2003/3/1 22:55:08

Are you sure that just isn't floating point code running faster on the G4?

Why are you thinking that???  With both parts running at the same speed, I dont think the FPU should be running at different speeds.  
    -Tig
 

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minator wrote:
BTW anyone know who did Altivec?
Most seem to assume it's a Motorola thing but thats not the case.  It was a joint project between IBM Motorola and Apple.  Apple did the Architecture.

BTW did you know you are completely wrong???   Though the PPC is an effort from all 3, though it draws strongly on IBM Power Architecture, all by themselves Motorola did Altivec.  Altivec of course led to the slow down in the PPC line and Intel passing them.   The great split between IBM & Motorola was all about Altivec, and until Apple and Motorola paid IBM to make 500 Mhz G4's, (because Motorola was throwing out more dies then they could keep) IBM didnt make any Altivec parts.   In addition since Motorola owned Altivec, IBM couldnt sell faster Altivec parts then Motorola, another bottleneck as Motorola did not spend sufficient resources to keep up with anyone in this regard.   IBM's 970 will be the first real effort by IBM at an Altivec aware PPC, its liable to remove Motorola PPC parts from all Apple products (if Apple doesnt go AMD as is rumored).    
    -Tig

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Deleted for duplication of previous message.
    -Tig

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strobe wrote:
Tigger, that's not correct at all. Ignore whomever gave you this misinformation from now on.

Ok, so Apple, IBM & Motorola lie in their public statements, and I should trust your source instead??

There was at no point a restriction made on IBM to produce slow CPUs, that's just 100% rumor bullshit. Motorola doesn't 'own' the instructions, only their implementation which they called AltiVec (which was originally called VMX and after Velocity Engine).

Thats completely untrue, IBM can only make G4's to make up shortcomings of Motorola per month, and cannot sell G4 class processors faster or cheaper then Motorola.   IBM can sell thier G3's at whatever speed and price they want,but thay cannot sell G4s in the same way.  Thats why the 970 is coming out, by reengineering Altivec, they no longer have to follow these rules.  

BTW Apple going AMD is another 100% bullshit rumor.
Stop reading rumors, I mean really.

Its a rumor thats going to be mentioned in two major magazines in April, it may not be true, but the Opteron rumor is big enough to be major story come April, so lets not act like I made it up.
         -Tig

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JetRacer wrote:
Let's ignore rumors and corporate statements.

Fact is that the G3 have a 133MHz bus, the G4 a 166MHz bus.

I think at the 400 Mhz rating I was comparing them at, they have the same bus speed.   Again I picked as close as I could to give a real delta.   Since Lightwave does not run without Altivec on a G4, I had to do what I did.    The 15% delta is pretty small (actually smaller then I thought we'd see), but is for a real world application and repeatable, so its much better info then the guess work we've seen elsewhere on this thread.  
    -Tig