Multi-Proccessor Madness!!

[YahooDave]

Well, not really, just a quick question I hope. I haven't worked with dual processors before and was wondering if two processors each running at say 500mhz are any better than one processor running at 1ghz. Assume these three processors are all the same brand and models.

[alex]

Well, I think it should work better than a single one, because both of them could work at the same time (I think !), and would have double the cache of a single one (amount of cache per processor * 2 processors = double cache in total )

I am not a professional computing god !, so I could not tell you with precision if it would work better, but that's what I think it will do !

[Rob Cork]

As I understand it, the performance of two 500-MHz cpus probably wouldn't be anywhere near as good as a single 1gig cpu, as the software has to be written to take advantage of both cpus properly - and most isn't. There was a great write-up about it all on oc.com not too long ago, though I can't seem to find a link to the article right now. Maybe someone else can.

Basically I think the gist of it was, if you're only going to use it for playing games/surfing the net/listening to music etc, you won't really see much of an improvement with dual cpus. But if you're using professional-level apps that are designed to utilise multiprocessing, you'll see huge improvements.

[Pitspawn]

Even at best a dual 500Mhz rig would compare close to something lying between a single 700-800Mhz processor. This is because they dont share the same cache, have to share bandwidth and both have trouble carrying out certain commands together. EG...

Lets say we want to compute 5+5+5+5.

Processor One adds 5 to 0
Processor Two has to wait for Processor One to get result before adding another 5.
This is inefficient. This code would be given just to one processor.

BUT, this sort of computation can be done by two processors....
5*5 + 10*10

Processor One computes 5*5
Processor Two computes 10*10
Processor One takes result from Processor Two and adds result together.
Still inefficient but faster than one processor.

[BigPappaP]

The advantages of multi-processors are that software can be specially designed for multi-threading. For apps such as photoshop -which utilizes this, 2*500mhz would be much faster than 1*1000. I'm not sure how this works out, but my educated guess would be this. I want to try to explain it but i probably wouldnt make a lot of sense - especially since i'm not sure if this is correct. Its like the difference between 1 guy doing a math problem or 2 guys doing easier problems - that combined solve the same problem that the 1 guy was working on. This is faster - but only if the 2 problems the 2 guys are working on are made to duplicate the same problem that the 1 guy is working on.. maybe that helps?