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ArsTechnica Compares the P4 and G4e: Part II
Deffexor writes "It looks like Hannibal of ArsTechnica fame has put Part 2 of his original comparison article between Intel's P4 and the Apple/Motorola G4e. In a nutshell, this second article covers the execution core, the AltiVec unit and SSE2, as well as a myriad of other interesting factoids. An interesting read, if not a little technically intense for those of us with less than a CE/EE degree. Have at it boys!"
i personally believe that flexibility of the assembly instructions as well as the number of instructions executed per cycle contribute greatly to the dominant speed (at any given MHz/GHz) of the ppc processor. compare any intel/amd processor to a ppc at the same clock speed, and the ppc will kick its x86 ass.
the high end ppc desktops are topping out around 900MHz, while the p4's are hitting 2GHz. there has to be another explanation besides the complaint that jobs is ignorantly sitting on his thumbs. i think he knows what he's doing.
note: i am not a mac zealot.. i don't even own a mac - only 4 x86 pc's (1 athlon, 2 p133, 1 p120). i simply can appreciate the speed of the ppc.
"I just want to thank my coach Eric a.k.a. Disco for shattering my reality..."
This article is extremely informative and gives you a good insight into how these processors are designed, as well as how they compare. I disagree with the poster though, you don't need a CE or EE degree to get the idea of what's going on. I'm a CE and I had classes on this sort of thing so yes I could follow all the gritty details, but I think the author did a good job of explaining things so that most people could understand. Also, I thought the author summed things up perfectly saying:
The preceding discussion should make it clear that the overall design approaches I outlined in the first article can be seen in the execution cores of each processor. The G4e continues its "wide and shallow" approach to performance, counting on instruction-level parallelism to allow it to squeeze the most performance out of code. The P4's "narrow and deep" approach, on the other hand, uses fewer execution units, eschewing ILP and betting instead on increases in clock speed to increase performance.
This is exactly the case. Unfortunately the popular masses don't understand all of this wide vs narrow stuff, so they go for the higher clock speeds. In reality, Intel is really pulling one over on us, charging more money and all we're getting is a higher clock rate, not a whole lot of performance gain. PPC has proven itself time and time again to be the better processor, but unfortunately they aren't used in very popular machines (mostly Macs,) so we don't get to reap the benefits.
On a related note, this article touches on one of the many reasons why the Gamecube will run circles around the Xbox. GameCube's processor is a 485Mhz PPC designed specifically for video games, while the Xbox just uses a common Pentium running at 733 MHz.
This all brings up a good question: why haven't Macintosh's or GameCube's marketers come up with a bench mark to put next to the processor speed? Maybe I missed it, but I've never seen a Macintosh commercial saying "comes with a G4 800 MHz, comparable to a P4 1.5 MHz." There might be too many legalities involved to do something like that, but it seems like they need to educate people somehow of the non 1 to 1 relationship between clock speeds of P4s and PPCs.
~ now you know
This all brings up a good question: why haven't Macintosh's or GameCube's marketers come up with a bench mark to put next to the processor speed? Maybe I missed it, but I've never seen a Macintosh commercial saying "comes with a G4 800 MHz, comparable to a P4 1.5 MHz." There might be too many legalities involved to do something like that, but it seems like they need to educate people somehow of the non 1 to 1 relationship between clock speeds of P4s and PPCs.
Cyrix used to sell PR parts, PR133 might have been a 116Mhz chip, but it was as fast as a 133Mhz pentium. So there's precedent, and it's probably legally OK, but I suspect the reason is it doesn't really matter.
What really matters is that the CPU is fast enough for what you want to do. I run OS9, OSX and linux on my machines. My home machine is a G3/350, and it's plenty fast for running OS9 for everthing but compressing MPEG1 video. It's not fast enough for running OSX. My work machine is a G4/400 and it's just fast enough for running OSX. But it's not fast enough for compressing MPEG1 video. If I had a dual-800 G4 it would be more than fast enough for OSX, but it would still be too slow for compressing MPEG1 video. My linux machine is a Dual-800, P3. It's just fast enough for running linux with all the crap I have running. It's still too slow for compressing MPEG1 video, though. I also use a 1.2GHz Athlon machine occasionally, and I consider that just fast enough to run Windows 2000. I assume XP is similar. But it would still take a long time to compress MPEG1 video.
So, how would you structure a comparison benchmark? SPECint? BYTEMark? PhotoShop duals? I think the answer is that you don't. It doesn't matter, as long as the computer is fast enough to do what you want it to do. The semi-annual MacWorld Photoshop duals are interesting since they actually show that the computer is too slow for designers but the Windows machines aren't any better. Perhaps they need to enunciate more, but I think their current stand of , "it's fast enough," is the mature one.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Feel free to debunk it. Explain why it's better for developers (and the user experience) to have to work out how to optimise to a new pipeline every couple of years, rather than to squeeze every last drop of speed out of one design before moving onto the next on (e.g.) a five year cycle.
The whole point of modern processor architectures is for the work of pipeline optimisation be done by either the processor or the compiler. The goal is less work for the application developer. This coincides with the trend towards higher level programming languages - I can't think of any large major applications architected such that the code needs to be hand optimized at instruction level. Sure, after profiling some parts may be tuned, but the size of applications today are just too difficult to design in overview with that scope. A huge amount of the transistor budget these days is taken by microcode that performs these optimizations on the fly, but with architectures such as Itanium you're seeing a move towards compile time ordering. But now I'm getting sidetracked...
Ever looked at the specification of a Playstation [e-scapegames.co.uk] and wondered how on earth developers got it to do what they had it doing by the end of its lifecycle?This is a time-honoured trend in closed-hardware systems. Look at the last generation of games on the SNES. Look at the scene demos being put out for the Amiga in the mid 90's, essentially a decade old hardware platform at that point.
Ever wondered why early Playstation 2 games bit the weenie?
All first generation titles do not harness the full capacity of a machine; I think this is your point. But on open systems developers don't have to optimize anything, thanks to Moore's Law. Maybe it doesn't strictly live up to the "small-is-beautiful" aesthetic, but software development is about optimizing results. Time will be spent where the greatest payoff is, and since performance boosts are a natural consequence of progress more resources are devoted to development.
It *is* fair to make these comparisons since the G4 and the P4 are the best Motorola and Intel have to offer us, right now. It's irrelevant what the G4 was "aimed at competing with"; what is relevant is what we have in our hands now.
If you are a consumer who wanted a comparison to decide which kind of computer to buy, you are right the article was (mostly) useless.
BUT, for the audience the article is intended for - geeks, technophiles, nerds & propeller heads it was not pointless at all. On this forum in particular there are a lot of people that use neither Windows nor MacOS but other operating sytems which run happily on either processor. Even if there is no *practical* point there is always sheer geek curiosity - alot of us find such articles entertaining.
Might as well have Car and Driver running a comparison of a Jaguar S-type and a 10-ton dumptruck.
I don't think that the difference between a P4 and a G4 is quite as wide as that - and they are being marketed by both sides as roughly equivalent products. Most techie people may know which is the "dumptruck" and which the "Jaguar" but it is still interesting to see a technical explanation of WHY and precisely HOW they are so different.
The whole market for motherboard upgrades comes from this situation. Apple does not support motherboard that it did not manufacture, and the OS used to check for the precence of genuine ROMs. So third parties could not build replacement boards. By upgrading only the CPU subsystem, the rest of the motherboard would remain genuine Apple and therefore run the system without problems.
Also remember that Mac hardware tends to be more expensive and last longer than PCs. While the performance boost you win by upgrading only the CPU system is lower, the impact on the workstation is also lower. Changing a motherboard means changing the system, having new drivers, so basically more maintainance work.
This situation might change with darwin, theoretically, nothing prevents some company from producing PPC motherboards, recompile Darwin for it and then build a installer that instals OS X on top of Darwin. Old machines that Apple does not support can run OS X this way.
> After the Pentium II generation of CPUs, things
> have gotten very, very muddled.
To continue with your engine analogy, after the fifties things have gotten more complex. Variable valve timing is common. BMW is working on technology (if it's not in production already) that opens/closes valves using electromagents - no more camshaft! All electrical. Probably both more reliable and more efficient.
Turbocharging is now common - the combination of a small displacement engine and turbo is commonly found and provides a good compromise of power and efficiency/mileage.
As the technology increases, designs become more complex. This isn't always a bad thing.
I'm pretty sure Adobe doesn't care whether you spend your $900 on the Windows or the Mac version of Photoshop.
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Cogito cogito, ergo cogito sum.