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Velocity Optimized
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Forum Regular
Join Date: May 2001
Location: South Wales, UK
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From the bouncemarks in the other topic, I find it hard to believe that the Veloctiy Engine does much for system performance in X. G4's are slightly faster than G3's regardless but havent apple done any V engine optimizations yet?
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osx.vr9.com
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Dedicated MacNNer
Join Date: Apr 2001
Location: Bethesda, MD
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I doubt Altivec would do you much good for starting applications or core OS operations. What its designed for is operating on vectors. It should be a big win for things like Quartz, where you deal with pixels and floating point vectors.
dave
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Senior User
Join Date: Oct 2000
Location: Paris, France
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The vectors the velocity engine deals with and the vectors in Quartz have absolutely nothing in common. To sum it up, a vector for quartz is the mathematical definition of a vector, a vector for AltiVec is a series of bits (ie 100111100111011) on which a similar operation can be done in a single cycle.
Try to keep this in mind.
AltiVec can help a lot for networking also, do not forget that.
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Soyons R�alistes, Demandons l'impossible
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Dedicated MacNNer
Join Date: Apr 2001
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Originally posted by SYN:
<STRONG>The vectors the velocity engine deals with and the vectors in Quartz have absolutely nothing in common. To sum it up, a vector for quartz is the mathematical definition of a vector, a vector for AltiVec is a series of bits (ie 100111100111011) on which a similar operation can be done in a single cycle.
Try to keep this in mind.
AltiVec can help a lot for networking also, do not forget that.</STRONG>
That's not really true. The altivec registers are 128 bits and can be chopped up into 8, 16 or 32 bit units. If you go 32 bits they can be integers or floating point numbers. Quartz represents numbers as floats also, so you can use the altivec unit to do math operations on 4 numbers at once, if you can organize your data that way.
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Addicted to MacNN
Join Date: Apr 2001
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To sum it up, a vector for quartz is the mathematical definition of a vector, a vector for AltiVec is a series of bits (ie 100111100111011) on which a similar operation can be done in a single cycle.
Actually AltiVec and Quartz use the mathematical definition of vectors. It's just that vectors can be used for more than just geometry, so AltiVec can be used to speed up more than Quartz (but it can - and probably does - speed up Quartz nevertheless).
Developer
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Nasrudin sat on a river bank when someone shouted to him from the opposite side: "Hey! how do I get across?" "You are across!" Nasrudin shouted back.
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Mac Elite
Join Date: Mar 2001
Location: London
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I think a fair bit of X is optimized for G4's coz in 9 G3 & G4's were about the same speed in the finder etc...
This is not the case with OS X...
It's just that you cannot optimize code for G4's all the time only certain types of code can be writen to take advantage of the G4's altivec engine...
Maths and vectors are prime candidates. Number crunching...
Thus quartz is speeded up a bit...
Thats from what I have seen.
Edd
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