Questions about OpenCL in Lion

[smirk]

Hi, I'm about to buy a new iMac and I'm trying to decide between getting 1 GB VRAM in the video card or 2 GB.

Isn't Lion supposed to farm out more processing to the GPU than prior versions of OS X? I thought I read something about Grand Central Dispatch using OpenCL automatically. If that's the case then I wonder how much video memory it would want to use.

Can anyone comment on this? Is it likely that down the road having the extra VRAM could lengthen the iMac's useable lifespan, since future OSes and anything using GCD will gain some kind of miraculous performance gain from OpenCL?

Thanks!

 

[jeanlain]

Hi, openCL uses GCD, not the other way around. All apps that use openCL need to include explicit openCL code.
OpenCL support has apparently improved in Lion. Maybe the newer radeon will support openCL 1.1, but I'm not sure.
I can't really advise you on the VRAM issue either.

 

[Bear]

Can anyone comment on this? Is it likely that down the road having the extra VRAM could lengthen the iMac's useable lifespan, since future OSes and anything using GCD will gain some kind of miraculous performance gain from OpenCL?

It's quite possible this will happen, However, my crystal ball needs polishing.

You don't say what you're using your computer for (nor how many screens you plan on having on it.) Without that it makes it even harder to guess how likely more VRAM will help you.

Has anyone checked if and how Mission Control and Spaces and such make use of extra VRAM?

 

[smirk]

Thanks for your replies.

I mostly use the computer for web browsing, making MP3s, Handbrake, iPhoto, maybe a little XCode, nothing too strenuous. Most of the time it will only be the built-in display, but sometimes I hook up a second display. Every now and then I'll play a game or make a movie in iMovie. So most of the time the computer won't be taxed, but I always like the potential to do more with it. It's a bummer when you go to play a new game or use a new OS feature down the road and the result is unsatisfactory because of a hardware limitation that could have been avoided by spending a little extra cash up front.

 

[jayhawk11]

Thanks for your replies.

I mostly use the computer for web browsing, making MP3s, Handbrake, iPhoto, maybe a little XCode, nothing too strenuous. Most of the time it will only be the built-in display, but sometimes I hook up a second display. Every now and then I'll play a game or make a movie in iMovie. So most of the time the computer won't be taxed, but I always like the potential to do more with it. It's a bummer when you go to play a new game or use a new OS feature down the road and the result is unsatisfactory because of a hardware limitation that could have been avoided by spending a little extra cash up front.

For that type of stuff, 2GB of vRAM versus 1GB makes literally no difference. It's more of a benefit for Pro-app users. Final Cut Pro X, for example, uses OpenCL to speed up processing.

That being said, the upgrade is only $100. So, if it fits in the budget, go for it. You can't change it down the road.

 

[t0mat0]

Not like it's going to be easy to upgrade it later on...
Worth the upfront payment.

 

[smirk]

Yep, that makes sense. Thanks for your input. I'm getting the 2 GB!