OT: Hyper-Threading in Current Mac Pros...

[Moved from: Re: Need advice- from a PC CS3 to a MAcBooK. I need to know what to buy.]


Thanks to Jeff for mentioning the "hyper-threading" aspect of the current Xeon 5500 "processors" used in Mac Pros. And, thanks to Joey for asking for more clarification. I, too, wasn't quite aware of this info (I believe I saw it initially, but most news websites and discussion forums missed the important details, so none of us should feel bad).

From Apple's current tech specs (today) at Mac Pro Tech Specs:

Quote

Hyper-Threading technology for up to 16 virtual cores

An aside (OT): How well are these "extra" threads handled in consideration of the rest of the hardware, especially RAM? I have read that 2 GB of RAM per core is minimal for optimal operation/efficiency and 4 GB per core is better. So with an 8 core Mac Pro, 32 GB is the most you can currently use. Does this mean that the additional "virtual" cores are somehow limited due to RAM, or other hardware, limitations? Sorry for the diversion...

(Oh, what the hell, I will move this to a new thread...) [Prior to moving post.]

Thanks for any info...


-Dave

P.S. - Thanks to all of the moderators and regular contributors. This forum is terrific!

A brief addendum...

My question, or pondering, is probably more relevant to a discussion of Compressor, or Qmaster, or both...

Or, put another way, do these additional "virtual cores" in the dual, quad-core (current model) Mac Pros double the effective processing power (plus some) compared with a similar clock speed 2008 model 8-core Mac Pros (yes, I know that the processors and other hardware are somewhat different)?

Or, is RAM, system architecture, etc., a limitation on these additional virtual cores (for lack of a better, simple name --- maybe Jeff's use of "logical processor" or the term "hyper-thread" is better???)?

Real-world performance benefits are what I'm really curious about...

Addendum:

I did a quick check of Apple's benchmarks (Mac Pro (2009) Benchmarks) and it seems that Compressor would fall into a 1.2x to 1.5x increase in performance over (slightly) different models of Mac Pro, comparing the new 2009 model to 2008 model.

Barefeats also has a few benchmarks showing a 1.2x to 1.7x increase from 2008 to 2009 Mac Pros (hard to compare similar models as processor speeds are different, etc.).

I haven't found anything that specifically relates RAM and the hyper-threading per core (two "virtual cores" per stated core). I would imagine there are other difference in hardware between the 2008 and 2009 Mac Pros besides the processors and RAM that influence overall, "real-world" performance. And, I still haven't found anything that mentions if the OS or applications are a limiting factor, or if it is just hardware.

For instance, it may be that the hyper-threading is utilized as much as it could be, due to RAM and other system limitations (HW and SW)...

I will stop here... I am getting in over my head...


-Dave

P.S. - I should have just asked how much faster is a 2009 Mac Pro versus a 2008 Mac Pro (with as similar a configuration as possible) in (1) transcoding video in Compressor; (2) in rendering in FCP 7; or (3) exporting video from FCP 7...

Also, sorry for my typing mistakes (I have gone over my two posts and tried to clean things up).