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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!"
This is exactly what I've been trying to find out for some time now. I've been increasingly upset with the x86 line of chips since it seems that there is hardly any diffrence between 600Mhz and 1.2Ghz.
A more interesting comparison will be to pit the P4 against the comming G5. According to the Register, Apple has begun seeding early G5's at up to 1.6GHz to key devlopers. Other sources are claiming limited yeilds in the 2.4GHz range already.
There's still bugs to be worked out before production ramps up for release early next year, and supposedly AltiVec will not be as strong on the G5 as it is in the G4. But at 2.4GHz on an already-superior FPU, who needs it?
But with the G5 around the corner, I think THAT will be THE interresting comparison.. expecially since Intel plans on keeping the P4 for a while (, ramping it up in speed, when you Read adobe saying the G5 are significantly faster than P4 (and if you go read the article, the same people do say that the P4 is faster than a G4 (exept for altivec stuff) so if they say G5 is faster than P4, it probably will be :)...it should be really nice to see something that kills the P4 in raw performance other than AMD).
--- Metamoderating abusive downgraders since my 300th post.
Note: I have a B.S. in computer science, a solid understanding of hardware issues, and have been programming for 19 years.
When I read articles like this, there's so much detail that I find myself--even willingly--losing sight of the big picture. Sure, you could read a detailed write-up about Toyota's new engine, but those details don't really matter much unless you've just made a hobby of knowing about engines. Realistically, you'll have a hard time connecting those details to your driving experience. Heck, someone could put in a different engine, tell you that its a Toyota, and you'd be saying things like "Oh, yes, this feels just like a Toyota, I can tell that the designers did blah and blah."
After the Pentium II generation of CPUs, things have gotten very, very muddled. Amazing features that are supposed to increase performance don't always do so. Sometimes they make things worse. Little compiler tweaks can make one program be twice as fast as another, given the same hardware. Chips with higher clock rates can be significantly slower than chips with 20% slower clocks. Certain applications run much faster than on previous chips, but there are others that show no increase.
It's all very chaotic and confusing, even for people in the know. I suspect that if you took a program that people claimed to need a P4 or Athlon for--something very performance sensitive--and set yourself the task of making it run faster on a PII than an Athlon, you could do it. But that doesn't matter, as everyone seems to be clamoring for newer chips.
Does anyone know if an ATX board with a G4 exists? I just started developing my own little OS and, frankly, x86 assembly stinks, I hadn't touched it for 4 years and didn't remember how crap that ISA indeed is. The 68k series were such a nice development platform, the PPC ISA looks quite cool as well.
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."
The problem is that you can compare processors in far too many ways. Apple likes to use Adobe Altivec-enabled applications when it compares speed (big suprise), but the reality is that comparing two processors is only marginally more useful than comparing two human beings. Computers are far too multi-purpose to be able to come up with a useful comparison.
Processors are even worse... It's like trying to compare two brains without letting education or experience skew the comparison.
In the end, manufacturers will choose from the dozens of possible benchmarks to make their processor look the best (or make up their own if none of the others will do).
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.
Two factors come into play here.
The first is that, if I remember correctly, PPC and x86 chips use a different clocking scheme. This means that clock rates between them aren't even directly comparable (what a "clock" is depends on the clocking scheme).
The second is that it's perfectly possible that the PPC architecture is limited to lower clock rates than the x86 architecte. Signal propagation through gates takes time. If one architecture expects signals to propagate through logic three gates deep per clock, and another architecture expects signals to propagate through logic five gates deep, then of *course* one will have a faster maximum clock rate than the other. They would hopefully still be doing the same amount of work per unit of real time.
You should already be familiar with this from the Athlon/P4 spin war. A 0.18 micron Athlon core simply cannot be clocked as quickly as a 0.18 micron P4 core - no matter what you do. Does this make the Athlon automatically a poor performer? No, because it can do more per clock. Does this make the Athlon automatically kill the P4, because it "can do more per clock"? No, because the P4 can be clocked faster. Only real benchmarks will tell.
A point against Apple is that Apple has been allergic to publishing SPECmarks for its processors for the past couple of years (the only PPC-ish benchmarks are IBM's benchmarks of the Power series of chips, which forked after the G3 IIRC). This removes a very consistent (if somewhat flawed) means of comparison.
I'm a CE as well, and I absolutely loved the article. It's nice to have someone fight the technical battles for you to release minute details about their procs. Trying to get information like this is usually like pulling teeth from some companies.
What I wanted to convey though, for people who may not deal on a hardware level with this stuff. Is that it is very hard to really get a good understanding for the whole processor. These projects are IMMENSE. Trying to keep track of millions of transistors, and lay them out, etc... is a nightmare. I know. So while it is good to talk about the higher level concepts of narrow Vs. Wide on a conceptual level that all falls away when you start looking at transistors. More than anything these projects are all about coordination. You can have a team of engineers working on a specific part that have NO IDEA what the other bits and pieces look like unless they have to interface with them. So just keep that in mind when we're judging these companies. I just think we lose sight of the massive scale of these projects sometime.
Of course there's another explanation-- namely, it's not Jobs who's sitting on his thumbs-- it's Motorola. (Ouch-- can you imagine Motorola sitting on Jobs' thumbs?)
Furthermore, Motorola isn't sitting on their collective thumbs-- they're simply targetting a market whose requirements are different from Apple's. The embedded market.
This is all hugely ironic, because the RISC architecture was s'posed to result in chips that could cycle faster but did less per cycle. Instead, it's the CISC chips that are cycling faster and doing less per cycle.