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Dual core processors - Not worth it?! Enable apps to use both?

L

LERsince1991

macrumors 65816
Original poster
Jul 24, 2008
1,245
37
UK
Hi,

I've been monitoring my activity monitor and by the looks of it nothing ever uses more than 100% of the cpu, I have a dual core and theres 200% available of course.

I've installed something called cuda as I thought this might change apps to use 200% but doesn't appear to have done anything?

Applications in particular are my CAD applications like AutoCAD and Google Sketchup - Both latest versions.

Could anyone enlighten me on why we have dual cores not actually doing anything?

Luke.

Attached an image of when I just set an application to do a big task - its using only 100%, note in the bottom left its states 45% idle... (its not, not responding, just doing a big task)

edited, found that programs can use one cpu, but running side by side they can run on one 100% each. What about enabling them to run at 200% each?
 

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Last edited:
Not all applications / processes / algorithms can scale across multiple cores *but* with a 2+ core machine, whilst one app "occupies" one entire core, other side tasks (email, web, etc) can be scheduled to use the other core, ensuring good responsiveness - I've definitely noticed this benefit on 1.66GHz C2D compared to a 3GHz P4.
 
True, many applications aren't written to take advantage of multiple cores, but you need to understand not all of the major processing tasks can be easily split up into multiple threads. Some tasks are easy, like converting video, processing large data sets (scientific, maths modules). It's one the most difficult areas of programming, how to a break single large task so it can be done concurrently, and efficiently.

What were you trying to do in InDesign/SketchUp/AutoCAD? Export video?

And CUDA is a GPU programming language. It won't increase core usage, in fact, if would probably decrease it since GPU usage isn't recorded under CPU usage (obviously). If you read the little descriptor in the 2nd attachment, you'll have discovered this already.
 
CAD isn't something that is CPU intensive, it's more GPU intensive. If you use something like handbrake to encode video you will see your CPU spike.
 
LERsince1991 said:
Hi,

edited, found that programs can use one cpu, but running side by side they can run on one 100% each. What about enabling them to run at 200% each?
Click to expand...

where would you get the extra 2 cores for a total of 400% usage? :s

Lots of programs go over 100%, second life uses upto 150% sometimes, handbrake pretty much uses whatever is spare.
 
LERsince1991 said:
edited, found that programs can use one cpu, but running side by side they can run on one 100% each. What about enabling them to run at 200% each?
Click to expand...

That's up to the developer of each program. Each developer has to find a way (there are several) to split tasks into multiple "pieces" so that one can be allocated to each CPU.

As others have said, the greatest benefit of multiple cores is responsiveness when there is something intensive going on.

When you get to a quad-core i7 or Xeon (8 logical cores), this is an even bigger benefit. My desktop never feels unresponsive, no matter how much is going on in the background.
 
thanks for the reply.
I could have sworn that I had autocad running at 200% sunday night. As When I installed cuda it loaded up on system preferences and it said version 4. Something. Morning after when I restarted system preferenceces came up automatically saying cuda was out of date then today it said there was an update avilable, not sure if that means anything.

When I said I wanted each app running at 200% I meant on there own at 200. Not simutaineously.

I think I'm not that bothered about dedicateding an entire cpu to background tasks like email.

The app open needs the power, as yes they become non responsive if it doesnt get the power.

I was just pushing them to the limit on purpose with everyday tasks in each app. Autocad I slected the whole drawing, and indesign I had overprint preview on when looking at big A0 layouts.
 
the reason I was asking this is to determine wether its worth getting a mac pro or not as I'm sort of outgrowing my laptop even though its only 2 years old.

Apart from responsiveness and whatever difference there is in ghz there won't be much difference?

Luke.
 
The vast majority of programs simply do not need that kind of power and those that do can either use it (parallel computing, e.g. running a filter on a photo you can split that task up or processing lots of data) or can't use it (a program that relies on branching a lot). CUDA is a technology relating to using the graphics processor to do more general purpose calculations, for example if you had a large set of vector operations to do in MATLAB then CUDA would be perfect, it is very limited as to what it can do though. Installing it will do squat.
 
Thanks for the info all!!

I found a bit of a helpful trick - its possible to copy+paste an application to have it running twice, say your working on 2 models in the same program and there big you can break them down into each processor each. allowing them to have 100% each. or export 2 massive batches at once :)
 
LERsince1991 said:
the reason I was asking this is to determine wether its worth getting a mac pro or not as I'm sort of outgrowing my laptop even though its only 2 years old.

Apart from responsiveness and whatever difference there is in ghz there won't be much difference?

Luke.
Click to expand...

If you're interested in the Mac Pro for a CPU speed bump only, you'll have to look above the base model to outcompete the top iMac. There are plenty of other reasons to get a base MP over an iMac, but this isn't one of them.

As many of others have said, this is a software issue, not hardware. Multicore-aware applications are slowly becoming more common. But, for now, and for most uses, a higher clock speed is much more advantageous than core count.
 
Kissaragi said:
where would you get the extra 2 cores for a total of 400% usage? :s

Lots of programs go over 100%, second life uses upto 150% sometimes, handbrake pretty much uses whatever is spare.
Click to expand...

Core i7 and Xeon processors have hyperthreading. ;)
 
LERsince1991 said:
Thanks for the info all!!

I found a bit of a helpful trick - its possible to copy+paste an application to have it running twice, say your working on 2 models in the same program and there big you can break them down into each processor each. allowing them to have 100% each. or export 2 massive batches at once :)
Click to expand...

I do this with Handbrake and Video Monkey for overnight encodes.
 
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