2.66 vs 3.0??

[shellbryson]

I thought having multiple processors was better than multicores. I know what the difference is physically, but whats the difference in how it works? and which is better? or would there technically not be any difference?

I'm not processor expert or anything but I believe it's a lot to do with caching and bandwidth. 4 cores in one package share a cache, whereas if you have multiple packages you have more cache per core, effectively. 2 x 2 packages with 2 cores = more cache than a single package with 4 cores. Then there's bandwidth. All the cores on a package share the same bandwidth, so if you have 4 cores, they have potencially less bandwidth per core...

 

[PerfectlyFlawed]

that makes sense, so aside from that I have the black 2.0GHz Macbook CD, I've always understood the multiple cores to be the same as multiple processors, but now I've started to learn a bit more and question that alot. so my macbook is each core actually operating at 2.0 GHz? or is it 2GHz chip with two cores that helps spread the load, but isn't exactly "two" 2Ghz processors like they are made out to be?

 

[dpaanlka]

I was under the impression that they are two processors - only soldered onto the same little board and sharing the same bus and cache. But still two actual processors.

This is why they show up as two processors (four in my Mac Pro) in Activity Monitor, in Cinebench, etc...

EDIT: I was also under the impression that Mac OS X itself is muti-core aware, and so can juggle non-multi-core-aware processes between multiple chips. Running a single processor process on one core and some other process on another core certainly is better than running both on a single core.

Finally, I was told by several people that some apps (iChat, Safari, iCal, Word) would simply perform worse when split between multiple cores rather than staying on one core, because they have to constantly switch information between the two (or something) and aren't processing enough information to actually make it worth it. I've never owned a multi-core machine until a week ago, so I'm not very clear on this.

 

[shellbryson]

that makes sense, so aside from that I have the black 2.0GHz Macbook CD, I've always understood the multiple cores to be the same as multiple processors, but now I've started to learn a bit more and question that alot. so my macbook is each core actually operating at 2.0 GHz? or is it 2GHz chip with two cores that helps spread the load, but isn't exactly "two" 2Ghz processors like they are made out to be?

Well, 2 cores in one package sharing a single lot of L3 cache (I think). So if you have a fully multi-processor aware program (as far as programs are concerned, multi-processor and multiple cores are the same thing) you could in theory have a "virtual 4ghz" to use (2 x 2ghz). I know that's seriously over-simplifying it, but it's along those lines. However it's never going to be as fast as two dedicated processors because dedicated processors each have the entire bus and a big fat cache.