Yet Another G5 Roundup

Lawrence Person writes "This article on Low End Mac talks about why the PowerPC 970 is so fast, covering its superiority to Intel chips in Multiply Accumulate, double precision arithmetic, and Fast Fourier Transforms, among other operations. A short, clear article for those who don't have the time to wade through Parts 1 and 2 of Ars Technica's exceptionally detailed dissection of the 970/G5." Trollaxor writes "IBM has a neat two-page history of the PowerPC architecture, detailing its evolution from the first RS/6000 chipsets in 1990, through the POWER ISA, and into the processors that we know and use today. A very interesting read."

Comments

FFT is a good mesure

[Baikala]

Fast Fourier Transform is bread and butter for the scientific comunity. This is a good news for sys admins at research centers like me.
Maybe I have a chance at getting one or two of these babies for the next year budget.

Okay

[Japer Lamar Crabb]

I understand the excitement over these machines, so I won't get all pissy about this, but...

Until these machines are widely available, each and every thread concerning the performance of the PPC 970 will run the risk of degenerating into a heated debate over whether the figures being offered are reliable. In other words, a flamefest.

Don't we already have enough of those around here?

Re:Okay

[Johnny Mnemonic]

Hey, I'm a Mac fan, and I totally agree--while this bodes well for the future, the benefits of the G5 are clearly application specific. So until you'll be able to test it yourself, with the apps that you use, compiled with whatever they're compiled with, it's just another flamefest.

That said--both you and I clicked the link to "Read More", didn't we?

Yea, but does it run Linux?

[Znonymous Coward]

Seriously. The G5 PowerMac has like 9 fans in it that are controlled by the OS (Mac OS X). It will be easy to run Linux on it, but will Linux properly control the fans to keep the system from burning up or flying off the desk?

Re:Yea, but does it run Linux?

[dhovis]

I think the tech documents say that if the OS does not provide thermal management, the fans will run at full speed. So it will be interesting to see if the thermal management will be provided under Linux.

Terrasoft (makers of Yellow Dog Linux) has said that they will support Linux on the G5, but it remains to be seen if they will be able to provide thermal management that won't void the warrenty. Terrasoft is an offical Apple Value Added Reseller, and they sell dual boot MacOS X/Linux systems that carry the full Apple warranty, so Apple may provide them with the info they need or else a binary driver that they can use.

It may also be that Apple will make the thermal management code open source as part of Darwin. If that is the case, then it can probably be converted into a kernel module without violating either the GPL or APSL.

Re:Yea, but does it run Linux?

[Duke Thomas]

I never thought of that. Why did Apple put the OS itself in charge of regulating the temperature? Why couldn't the fans be controlled by some simple thermostat like mechanism quite apart from the operating system? Apple has been big on software controlling hardware for a while now, but this seems a bit much.

Re:Yea, but does it run Linux?

[MrTangent]

There are actually two hard drive bays. Look closely.

The lack of more than two hard drive bays was a concern of mine as well, but the drive that ships with the G5's is 60 to 250 gigabyte Serial ATA. Factor in the plethora of fast Firewire/Firewire 800 external drives and most Mac users will be as happy as pigs in shit (as well as Fibre channel XServe Raid for multi-terabyte storage for the higher end users). So you can get half a terabyte internal Serial ATA in the G5's if you chose to pay the premium. I think that's more than enough for 99% of the population.

I do agree there's some aspects of the G5 design that seem like a step backwards over the previous G3 & G4 'El Capitan' case. While two hard drive spaces is fine for most users, the G4 allowed you to have four internal hard drives. The lack of a second optical drive bay is also a "step backwards" over the G4 design (this can be rectified with an external Firewire drive if needed, and again, most users don't require a second optical drive).

For me though the biggest gripe I have with the G5 case is the removal of the drop-down motherboard door design on the G3 (Blue and White) and G4. The one button access with drop-down door was an amazing feat of engineering and it saddens me to see this go. The new G5's internals are very elegant but installing and upgrading RAM, PCI and AGP cards is so much easier on the previous G4 and G3 models (although the G5 certainly looks easier to upgrade/get into than most PC boxes I've worked on before).

As far as the fans go, I have no gripe there. While it might be more moving parts, the idea of thermal zones is a sound idea and will help keep the machine cool and output less decibels. By the way, the fans will be replaceable. You make it sound like the machine will be junk just because one fan fails. I'm sure Apple has thought of this and will provide replacement fans.

One could also argue that by having nine fans that work in tandem you'll have less chance for failure since no one fan will be running at 100% at all times like on other machines. This quote kind of explains what I mean:

"the candle that burns twice as bright burns half as long."

Ah yes, the early days!

[dbirchall]

In April of 1990, I was visiting a friend at Utah State University in Logan, UT. The IBM rep (nice lady) came around to the computer center (which was nice of her) to try to sell everyone PS/2's - or at least PS/1's (which was less nice of her).

But she brought this one thing with her that looked kind of like an overgrown PS/2, and had a goshawfulbig monitor hooked to it... and was running UNIX. Being a geek even back then, I noticed this and asked what it was and if I could play with it.

'Twas some very early RS/6000 model, quite unstable at that point in time, OS-wise. I have no idea why she was allowed to bring it on campus. Maybe she was trying to convince them to move away from their Ultrix vaxen.

By IBM's timeline, that would have been a POWER (no numbers after it) chip, predating the PowerPC by a chunk of time. I never stopped to think about it before, though.

Multiply and add

[Matthias Wiesmann]

One thing that irks me in the low-end mac article is that it states that the G5 can do a multiply add in one cycle. While this is true, this is nothing special about the G5, the multiply and add instruction has been in the PowerPC instruction set since the start - my Powermac 7100 (technically à G1) already could do this. This is in fact pointed out in the intersting article by IBM about PowerPC.

Re:I just think it's pointless until

[dhovis]

Actually, that isn't really true. Because of the way the PPC ISA is set up, there isn't much advantage to switching the whole OS to pure 64 bit. The main boost you are going to see here is the ability to use more than 4GB memory, and you can implement that on the G5 with just a recompile.

Individual apps can be switched to 64-bit and operate in 64-bit mode if needed, even if the OS doesn't use 64-bit mode itself, so long as the OS supports 64-bit addressing

Unless you need to do 64bit integer math, your app will see no benefit from switching to pure 64-bit. In fact, your app may slow down and waste memory. But an app can still take advantage of the main benefit of more addressible memory whilest staying (essentially) a 32-bit app. This is thanks to the fact that PPC is a 64-bit architecture with a 32-bit subset.

There are still optimizations that need to be done to improve the compilers for the G5, but very few of those optimizations have anything to do with being able to do 64-bit integer math.