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New MP 8 core, or is it 16 cores?

F

fedeboraxx

macrumors newbie
Original poster
Aug 16, 2010
27
1
hey guys

i have the new MP 8 core, and when i load up iStat menus, 16 graphs are displayed (for the CPU section). what does this mean? some sort of hyper-threading deal? in any case, it looks like a lot of processing power
 
Up to 24 virtual cores.

The Intel Xeon processors support Hyper-Threading, which allows two threads to run simultaneously on each core. So, for example, a 12-core Mac Pro presents 24 virtual cores that are recognized by Mac OS X. Performance is enhanced because Hyper-Threading enables the processor to take better advantage of the execution resources available in each core.
Click to expand...

from http://www.apple.com/macpro/features/processor.html
 
There are 8 physical cores in the 8-core Mac Pro but each core can process up to two threads due to Hyper-Threading so there are 8 "virtual" cores as well that show up in the Activity Monitor or iStat, making it a total of 16 cores (8 physical + 8 virtual)
 
Hellhammer explained this right on key. You have 8 physical cores, but you have a virtual core for each of those physical cores which gives you a total of 16 cores being displayed, this is due to hyperthreading, but most apps won't take advantage of all 16. Handbrake will.
 
nice. thanks for the explanation. here's hoping apps start taking full advantage of these machines. i find it insane that still an app like after effects can almost freeze it to a halt when rendering. and rendering something dead simple
 
fedeboraxx said:
nice. thanks for the explanation. here's hoping apps start taking full advantage of these machines. i find it insane that still an app like after effects can almost freeze it to a halt when rendering. and rendering something dead simple
Click to expand...

How much RAM do you have? It's not always the CPU what is the bottleneck, if you don't have enough RAM, it will slow down
 
Hellhammer said:
T so there are 8 "virtual" cores as well that show up in the Activity Monitor or iStat, making it a total of 16 cores (8 physical + 8 virtual)
Click to expand...
That threw me for a loop when I first got my i7-930. I saw 8 cores and I thought I bought a quad core CPU. I was excited at first because I thought I got a "bonus" Still that's pretty impressive, of intel to virtualize the cores.
 
I hijack this thread for just a quick question...

Does a virtual core perform less than a physical core?

I'll explain myself

compare this 2 processors (iMac)

i5-680 dual-core: 3,60Ghz (3,86 with Turbo)+ Hypertreading -----> 2 real + 2 virtual cores
i5-760 quad-core: 2,8Ghz (3,46 with Turbo) no-hypertreading -----> 4 real cores

Reading only the specs, why should i buy the 4 cores one?

The dual core should always perform better in single threaded apps and in multithreaded apps

Am i wrong?
 
ugru said:
I hijack this thread for just a quick question...

Does a virtual core perform less than a physical core?

I'll explain myself

compare this 2 processors (iMac)

i5-680 dual-core: 3,60Ghz (3,86 with Turbo)+ Hypertreading -----> 2 real + 2 virtual cores
i5-760 quad-core: 2,8Ghz (3,46 with Turbo) no-hypertreading -----> 4 real cores

Reading only the specs, why should i buy the 4 cores one?

The dual core should always perform better in single threaded apps and in multithreaded apps

Am i wrong?
Click to expand...

Virtual core is never as good as physical. This AnandTech article should answer most of your question (I know it doesn't compare the processors you listed but see i5-750 and i5-661). In single threaded apps, the dual core is faster due faster clock speed but remember that Lynnfield quads have fairly aggressive Turbo
 
ugru said:
I hijack this thread for just a quick question...

Does a virtual core perform less than a physical core?

I'll explain myself

compare this 2 processors (iMac)

i5-680 dual-core: 3,60Ghz (3,86 with Turbo)+ Hypertreading -----> 2 real + 2 virtual cores
i5-760 quad-core: 2,8Ghz (3,46 with Turbo) no-hypertreading -----> 4 real cores

Reading only the specs, why should i buy the 4 cores one?

The dual core should always perform better in single threaded apps and in multithreaded apps

Am i wrong?
Click to expand...

You are. Virtual cores don't have the same performance than physical cores.
The dual core will be a little faster in single threaded apps due to its 400MHz clock speed advantage.
In multithreaded apps the dual however has only 7.2GHz of physical processing power, plus 10 to 15% additional performance duo to HT.
The Quad gives you 11.2GHz in multithreaded apps.
 
Thanks, that is what i wanted to know...

hyperthreading does not really double raw processing power, is more marketing stuff...
 
Doubling the number of full cores doesn't double processing power, so of course having HT isn't going to double it.

The HT cores don't give the same power as having twice as many full cores, but with some apps it comes much closer than you might expect. "Virtual" or no, when you actually benchmark the improvement in performance, it can be significant, not just marketing fluff.

For example, with Logic on a MP quad or i7 imac having HT on can improve performance by 60%. That's a big boost. Apps like handbrake or MAX are sped up quite a bit as well, although I haven't had a chance to benchmark.
 
HT (Hyperthreading) has been around for quite sometime. It's nothing new. HT was, I believe, first introduced on the Pentium 4's. If anyone is familiar with how God awful those processors were compared to AMD's at the time, then you might think twice at "awesome" HT is on the new Intel processors.

It is a fact that Intel makes some of the fastest processors in the world. But as someone else has already said, I find Hyperthreading to be more of a marketing ploy than anything.

Wait till AMD's bulldozer processor's to come out.
 
Wyldechild said:
HT (Hyperthreading) has been around for quite sometime. It's nothing new. HT was, I believe, first introduced on the Pentium 4's. If anyone is familiar with how God awful those processors were compared to AMD's at the time, then you might think twice at "awesome" HT is on the new Intel processors.

It is a fact that Intel makes some of the fastest processors in the world. But as someone else has already said, I find Hyperthreading to be more of a marketing ploy than anything.

Wait till AMD's bulldozer processor's to come out.
Click to expand...

Everything is a marketing ploy unless your usage is heavy enough to take advantage of the extra threads. Most consumers would be fine with 2GHz dual cores without HT or Turbo or other features.

Intel claims that the first gen HT took only 5% more die area but delivered up to 30% better performance. Doesn't sound that bad IMO. AMD is adopting same kinda technology with Fusion IIRC
 
The implementation of HT on current chips is completely different from that on the first generation years ago.

It's easy enough to do a comparison with HT on and off, fire up something like Handbrake and test it out for yourself before making uninformed statements.
 
Hellhammer said:
Everything is a marketing ploy unless your usage is heavy enough to take advantage of the extra threads. Most consumers would be fine with 2GHz dual cores without HT or Turbo or other features.

Intel claims that the first gen HT took only 5% more die area but delivered up to 30% better performance. Doesn't sound that bad IMO. AMD is adopting same kinda technology with Fusion IIRC
Click to expand...

Yes, AMD is basically taking Intel's hyperthreading but making it physical instead of virtual.
 
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