Comparative G5/G4 Tests

rocketjam writes "Barefeats.com has posted test results comparing a 2GHz G5 MP, 1.8GHz G5, 1.6GHz G5 and G4 MP's at 1.4GHz, 1.25GHz and 1GHz. They use Photoshop, Cinebench 2003 and a Bryce 5 render for tests. Bottom line is the G5 2GHz MP has the best bang for your buck, but you might think twice about trading in that dual processor G4 for a solo G5...the G4s hold their own quite well. They also say tests in Panther yielded significant increases in the G5 scores."

Comments

caveats about these tests

[hype7]

there's a lot of performance to be sucked out of the G5s yet.

A lot of programs are yet to be at all tweaked for the G5s. There are a couple of new processor functions (hardware square root for instance) that may bring big gains. Also, there are old functions from the G4 that slow down the G5. Check out Apple's G5 performance primer. I read that the changes are enough to make the guy who made the mac rc5 engine want to re-write it for the G5 (no simple tweaks). He was hoping to get by with just some minor tinkering, but the chip does require a lot more than that to take advantage of it's potential.

Let me take another example; regarding CineBench.
http://www.postforum.com/forums/read.php?f=6&i=874 58&t=87424

In that post, a guy called Richard from the Maxon development labs says this:

"OK, some news directly from the MAXON development lab:

Of course all the following numbers are not final, no promise at all !!!!!!!

This is based on the information we have right, now, there is still a of of work to do and we still have to wait for a new compiler...

With the current CineBench a single G5 1.8GHz scores at about 188, the optimized version will maybe score at about 238...

A hypothetical single G5 2.0GHz could score at about 210 on the old CB, optimized could be 265...

A dual G5 2.0 could maybe score at about 480 with the optimized version of CB....

Depending on the new compilers and our findings (thanks a lot to Apple for being extremely helpful and cooperative) we might even crack the 500 score for the dual G5 2GHz...

Again, no promise and of course no release date ;)

Cheers, Richard"

This compares to a 1.8ghz G5 score that I've seen of 188. Which means they're aiming to get a fair bit out of optimisation for the chip. Just as a means of further comparison...
http://www.imashination.com/bench.h tml

You'll see the top score these people have recorded is for a dual Xeon 2.4ghz - with a score of 502. If the G5s make it up to over 500, that says a lot about the chip.

Finally, you've also got to include a mention of the compilers. Whilst some optimisation has been made to GCC, the GCC guys rejected a whole heap of improvements for the G5 because they were too platform specific. There's a good thread over at Ars Technica that discusses some pretty big gains when using the IBM XLC compiler. Other Mac-specific compilers should yield some pretty awesome gains too.

So, in summary - take these scores with a grain of salt. They're just the beginning.

-- james

Re:Hmm. Not much of a review.

[Toraz Chryx]

g{The G5 is NOT going to excel at Altivec optimised code, the G4 will remain the Altivec champ until IBM puts the kind of Altivec resources onto the 970 that Moto put onto the 745x series}g

That's not strictly true, the problem is that altivec that's optimal for the 745x chips is worst case for the 970, since best case on the 745x makes heavy use of the vec_dst (prefetch) instruction, which is handled serially on the 970 and hence stalls the Altivec hardware.

also the G5 is a lot less likely to run into bandwidth bottlenecks with altivec code on large datasets.

Re:Not hard to do

[Anonymous Coward]

Why on earth should I choose a G5 over a dual G4?

The G5 is faster.

The G5 accommodates four times the RAM (roughly), and the RAM is considerably faster.

The G5 has AGP 8x.

The G5 has USB 2.0.

The G5 has FireWire 800. (The last generation G4 did, but the generation currently being sold by Apple is next-to-last and so does not.)

The G5 has Airport Extreme. (Ditto.)

The G5 has Bluetooth. (Ditto.)

The G5 has internal serial ATA.

The G5 has digital audio I/O.

The G5 is considerably quieter.

If none of that stuff matters to you, get the G4. If it matters, get the G5. This isn't a clear-cut case of "G5 better than G4 in every way." But neither is it even remotely a case of "no reason to buy G5."

Old Myth

[Llywelyn]

". The code is optimized for the mac. My friends P4 2.8ghz is only a little faster than my G4 733. Apple took advantage of this for years and had test results based on photoshop."

Your working with outdated information--by about 7 years.

The code is optimized for both platforms very heavily. A large portion of Photoshop's userbase is on Wintel machines and they were also paid (by Intel) awhile back to optimize their filters for Intel processors. Presumably they care about performance and keep both versions highly optimized. Saying that it is "more highly" optimized for the Mac is a fallacy--it hasn't even had more time to become optimized for the Mac, due to processor changes. The optimizations for the G3 and G4 are /somewhat/ different than those for prior PowerPC processors and the optimizations that took place for the G4 (such as using vec_dst in the AltiVec optimized portions of the code) actually work against the G5.

I also heard a rumor, though I am not sure that it is true, that Photoshop would offload its interface to the graphics card for display on its own and that, with the introduction of QE, Photoshop was effectively rendering its display elements twice. This may be completely unsubstantiated though :-)

While in general your point is good--that apps which are highly optimized for one platform are not necessarily highly optimized for another--Photoshop is a bad example.

Re:Hmm. Not much of a review.

[Llywelyn]

"The G5 is NOT going to excel at Altivec optimised code, the G4 will remain the Altivec champ until IBM puts the kind of Altivec resources onto the 970 that Moto put onto the 745x series. "

Another poster has already mentioned the execution sterilization that occurs thanks to optimizations that worked quite well in the G4 (vec_dst et al), but there is another point on this issue that needs to be mentioned.

Even if the G5 performs slightly slower than the G4e with AltiVec enhanced code on an individual, it has the potential to be much much faster overall simply due to the architecture. One of the main problems with AltiVec on the G4e currently is that many of the apps that take advantage of it are /bandwidth limited/. The architecture that the G5 is based on is radically faster when it comes to things like loading from main memory or making optimal use of both processors.

PCI-X (one other thing)

[Llywelyn]

The G5 supports PCI-X.

Re:What about Panther gains for the G4s?

[HTH NE1]

I'm getting a G5 for my home, but that's because I do heavy video editing and effects, which should benefit a LOT from the faster system.

And you're not concerned with the 50% reduction in internal drive bays as compared to the G4? I already have 650 GB shoehorned into my Blue & White G3 for video (upgraded to a G4 processor), and that's not counting the boot drive. The G5 only has two hard drive bays and one optical drive bay compared to the four and two in the G4.