How many processors does X support?

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kon21

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I can't seem to find any documentation on how many processors OS X can support. I absolutly love my Dual 500. Any chance of seeing Quad's in the future?
 
I don't think OS X currently would support more than 2 processors in one machine, correct me if i'm wrong, anyone. Quad processor systems are a possibility but not anytime soon, Apple still needs to work the kinks out of their dual-processor systems. The dual-processor systems as they stan right now are not nearly as effective as they ought to be. The main thing holding them from their full potential are software makers: though OS X natively can let any app written for it use more than one processor, if the program isn't coded to take advantage of it, you will not see hardly any speed boost at all. The program just uses both processors as one to do the same tasks rather than utilizing both at once to get the real speed advantage. Right now the only real advantage to dual processor systems comes in for multi-tasking, it just lets you run more apps effectively at once. The second major factor holding back dual processor systems is the bus speed. The dual 1ghz G4 runs on the same bus speed as the 933mhz G4. The bus on the dual machine has to be shared between 2 higher speed processors, cutting out a lot of speed potential. Dual-processor sytems ought to have twice as fast a bus as single processor machines, allowing both processors a full bus bandwidth.
 
In OS X an app doesn't need to be specially written to take advantage of dual processors, it just needs to have multiple threads. I think that in OS 9 and before though, there were special calls to use multiple CPUs, as you say.

Obviously, if a program is single-threaded, no OS on earth will take advantage of multiprocessors - you need some parallelism to be able to run separate tasks on separate processors.

My guess would be that Apple is selling few enough of the dual proc computers, there would just be no reward for them to make more than that. On the other hand, once you have dual processors, it ought not to be a huge step to run on more than that. If people start making non-Mac PPC computers (IBM released a royalty-free design that anyone could manufacture, I think), there might be a chance to install OS X/Darwin on them...
 
I think I read somewhere that the G4 processors are not optimized for multiprocessing beyong 2 processors. If anyone is more knowledgable, please correct me. I believe Mac OS X cannot support more than two processors right now. The IBM PowerPC reference design was the CHRP (Common Harware Reference Platform), which was a decendent of - now my memory is really sketchy here - PPCP (PowerPC Platform)? Anyway, it was a reference platform conceived by Apple, Motorola, and IBM when they united for the PowerPC chip and the "Pink" OS.

-B
 
The G4 is build to support up to 32 CPUs in one Computer. :eek: (Or even more I think)

I'm sure Apple will build Servers with up to 4 CPUs! At least when they have the G5 and want to get rid of the "old, slow" G4s!:p :D :)
 
The newest IBM design is called POP - powerpc open platform. This is only about two years old, I think. Here is a page with a bit of info about different makers who plan to offer POP computers.
 
The kernel of OS X currently is only configured to handle 2 processors (there's some command line command that says "kernel configured to support 2 processors" or something like that, but I can't remember the command). However, I believe UNIX can support up to 32 processors, it's just that the kernel needs to be reconfigured.

G4s, I believe, can also be released in multiprocessor systems with more than 2 processors. I'm not sure what the limit is, but I'm pretty sure that quad processors are a possibility, although I'd bet that Apple would rather like to increase the efficiency of each processor rather than add another processor.

UPDATE: The command line command is hostinfo
 
I quizzed a Apple techie at MacWorld Expo earlier this year about multi-processor support and said that yes currently OS X only supports 2 processors and that yes Apple has been playing around with the idea of supporting more than 2 processors, but there are some low level kernal issues that bring up instability. Something to do with instruction requests and timing. The specifics to what was said escape me at the moment, but this is something Apple is working on to provide the ability.

Now will this be something they will market to the consumer??

I hope so, I would love the idea to someday go onto Apple's web site and place a BTO for a Quad G6 or G7 w/10GB ram.

Now tell me what I'll do with that... maybe just some light Word Processing..:p
 
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