[Eug]

I know Snow Leopard 10.6 supports OpenCL, but does it use it all?

So far I have not found any apps that use OpenCL besides benches.

[chabig]

How can you even tell?

[Eug]

If OS X did use OpenCL, perhaps a machine with an OpenCL compliant card would have less CPU usage than a machine without one.

However, I was really just wondering if any of the developers might know. I get the impression that OS X doesn't actually use OpenCL, because the tech blurbs keep emphasizing that OS X supports it, for usage like speeding up scientific calculations.

"once developers begin to use OpenCL in their applications, you’ll experience greatly improved speed in a wide spectrum of applications."

I suspect Final Cut Studio in its next iteration might utilize OpenCL though. Also, OpenCL could be used in iPhoto and iMovie eventually.

"Media applications can perform complex, intensive operations with larger video and graphics files."

BTW, I'm reading Apple has the most complete set of tools so far for OpenCL programming, so it seems they're really trying to push it.

[Simon]

Of course Snow Leopard uses OpenCL. In Snow Leopard, Core Image has been re-implemented using OpenCL.

[Eug]

Link?

Considering Core Image still works fine utilizing the GPU on older machines, are you saying Core Image has several fallback levels now? eg:

Radeon 4850 --> OpenCL
Radeon 9600 --> OpenGL
Radeon 9200 --> CPU

[cgc]

Apple pushes lots of technology that is underutilized...anyone remember Cider?

[Simon]

Originally Posted by Eug 

Link?

I'm sure you'll find it in John Siracusa's article on Snow Leopard.

[Eug]

Originally Posted by cgc 

Apple pushes lots of technology that is underutilized...anyone remember Cider?

To be fair, OpenCL is very, very young.

The spec was only approved at the end of last year.

Originally Posted by Simon 

I'm sure you'll find it in John Siracusa's article on Snow Leopard.

I did, thx. It was almost mentioned in passing, and I guess I missed it.

"(Oh, and by the way, remember Core Image? That's another API that needs to compile code just-in-time and ship it off to execute on parallel hardware like GPUs and multi-core CPUs. In Snow Leopard, Core Image has been re-implemented using OpenCL, producing a hefty 25% overall performance boost.)"

However, that means there must be that fall back then, probably to OpenGL. I can't test this myself, but my understanding is that Core Image in Snow Leopard continues to work fine on older GPUs that do not support OpenCL.

Originally Posted by chabig 

How can you even tell?

Knowing the above, one way to test might just be to test Core Image in OS X 10.5 vs 10.6. eg. Benchmark Aperture in the two OSes to compare batch image export times, etc.

Is it safe to assume that Core Video has also been re-implemented with OpenCL? If so, you could also do it with Final Cut Studio or presumably iMovie.

Or you could run iMaginator, which is a Core Image based application.

There's also the OpenCL Benchmark, but it's quite irritating to run, and of course it doesn't run on 10.5. BTW, here is a, OpenCL Benchmark results page. The benchmark page unfortunately is currently pretty useless, because people are not running the same tests within OpenCL Benchmark. I blame the benchmark itself, because it's not n00b proof.

P.S. It should be noted that for ATI GPUs, some OpenCL-related fixes are coming in 10.6.2.

[The Godfather]

Maybe OpenCL can boost the new 13" MBP performance much above the previous generation. I'd like someone empirically measuring iMovie speedup, for example.

[P]

Originally Posted by Eug 

However, that means there must be that fall back then, probably to OpenGL. I can't test this myself, but my understanding is that Core Image in Snow Leopard continues to work fine on older GPUs that do not support OpenCL.

OpenCL is simply an API. When an app calls that API, the OS attempts to execute that call on the fastest possible hardware. If the GPU driver reports that the GPU can do it faster than the CPU, it is executed on the GPU. If not, it executes on the CPU.

EDIT: I did not realize that this was a zombie thread. Sorry.