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Grand Central Dispatch and Open CL Bring Significant Performance Improvements for Optimized Applications

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Apr 12, 2001
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Hardmac reports on a performance comparison between Mac OS X Leopard and Mac OS X Snow Leopard from Christophe Ducommun, developer of MovieGate, a video encoding and DVD creation software package. Ducommun, who is optimizing his application to take advantage of the Grand Central Dispatch and Open CL features of Snow Leopard, has found remarkable performance improvements for his software on the operating system when running on a Mac Pro.
Christophe Ducommun who keeps optimizing Snow Leopard for his application MovieGate just sent us results to illustrate how Snow Leopard can improve performance when one can make use of Grand Central and Open CL. Tests below have been performed with a Mac Pro 2007 (Quad Core 2.66 GHz with a GeForce 8800 GT).
Click to expand...
The results include an approximately 50% increase in video encoding speed when compared to Leopard, while also reducing the CPU load during video decoding by passing some of the work to the graphics processing unit.
Snow Leopard
150 frame/s for encoding in MPEG-2
70% CPU load for decoding
130% CPU load for MPEG-2 encoding (ffmpeg)

Leopard
104 frame/s for encoding in MPEG-2
165% CPU load for decoding
100% CPU load for MPEG-2 encoding (ffmpeg)
Click to expand...
While Ducommun's experience is relatively rare at this point due to the inability for the vast majority of applications to make such comprehensive use of Grand Central Dispatch and Open CL at this time, it highlights the potential performance gains these core technologies can bring to Mac OS X as developers begin to take advantage of them.

Article Link: Grand Central Dispatch and Open CL Bring Significant Performance Improvements for Optimized Applications
 
Article Link
https://www.macrumors.com/2009/09/16/grand-central-dispatch-and-open-cl-bring-significant-performance-improvements-for-optimized-applications/
are apple apps optimized for Snow Leopard?

I'd like to know which Apple apps are already optimized. For example, Logic 9?
 
Shake 'n' Bake said:
Probably none are.

I'd like a GCD/Open CL-capable iMove, Keynote, iDVD, Handbrake, iPhoto, FCS, and Logic Studio, along with Finder.
Click to expand...

Indeed.

You know, I would have expected either FCS 3 to arrive after the launch of Snow Leopard, and boast about how fast these apps (or at least some actions) are using GCD and OpenCL, or have a few updates for these apps to make use of these optimizations.
Strangely, nothing can be found.

Probably iLife 10 etc..?
 
I desperately want GC/OpenCL optimized Handbrake, but the developers have been saying for a long time that it is probably nowhere near, and may never come at all. At first they said it was because of Handbrake being cross platform, and more recently they say that it's out of their hands and up to the people who make the encoder they use.
 
Shake 'n' Bake said:
Most likely. That's why I'm not getting iLife or iWork '09. '10 will be GCD/Open CL-compatible for sure and written in 64-bit Cocoa. If not, that'd be a pretty stupid move.
Click to expand...

I want that too, but I wouldn't bet on it - I mean, Logic 9 and FCS 3 was released a little over a month before Snow Leopard, and they weren't even optimized (Pro apps you would figure would be first in line for a rewrite).
 
FSMBP said:
I want that too, but I wouldn't bet on it - I mean, Logic 9 and FCS 3 was released a little over a month before Snow Leopard, and they weren't even optimized (Pro apps you would figure would be first in line for a rewrite).
Click to expand...

Not a surprise to me. Wouldn't you need SL to be absolutely sure the app would work? If so, then an new suite or a 3.X.0 update may be coming.
 
FFMPEG for SL

Perhaps he could take the time to work on ffmpeg and tune it to use GCD and OpenCL?

He'd see far more improvements at that level which would benefit the entire chain of execution for his product as well, not to mention we'd all benefit from an optimized ffmpeg.
 
How much developer work is required to optimize an application? Even with the proven benefits, I'm curious what percentage of developers will take advance of these technologies.
 
Chaszmyr said:
I desperately want GC/OpenCL optimized Handbrake, but the developers have been saying for a long time that it is probably nowhere near, and may never come at all. At first they said it was because of Handbrake being cross platform, and more recently they say that it's out of their hands and up to the people who make the encoder they use.
Click to expand...
Handbrake relies on other open source projects to do the en/decoding, such as x264 and ffmpeg. So unless you want to optimize and port a Mac version with OpenCL and GrandCentral yourself don't hold your breath.

Until recently the developer API for OpenCL wasn't even available which is why you won't see it in many apps. On the GC side, now that Apple has open sourced it as libdispatch, it's entirely possible more OSes and developers will start using that. But it may take years for that to standardize and happen.

I'd imagine it may only be a matter of time before Apple updates its own Compressor to take better advantage.
 
Chaszmyr said:
I desperately want GC/OpenCL optimized Handbrake, but the developers have been saying for a long time that it is probably nowhere near, and may never come at all.
Click to expand...

To be honest, GCD isn't a big deal for Handbrake, at least on average machines. It already makes pretty canny decisions about threads.

OpenCL would bring serious gains, but we're looking to x264 for that – and they're not OS X-centric. If and when OpenCL spreads cross-platform (and GPU makers do seem keen on including it in their offerings) they'll almost certainly take more interest.
 
Very good news. Now if only all the apps for macs would take advantage of GCD & OCL.
 
Heh! The guy has (almost) the same rig is me (see my sig) but I have 2x his cores :D I've been waiting for this type of confirmation ever since GSD and OpenCL technologies were announced. If he got almost a 50% increase with a quad core machine i expect crazy numbers from an 8-core variety. Maybe ~200fps encoding rate.

I like handbrake but I'm not married to it. If there was another application out there (even paid, but reasonably priced) which could nab me 50-100%% gains I'd be all over it.
 
Handbrake is nice but the majority of Apple's machines sadly are dual cores. What I'd like to know is how much more performance you can squeeze out.

4 cores, 4 threads per socket on Core 2 is getting old too. Nehalem needs to make more of a showing at Apple.
 
borcanm said:
Very good news. Now if only all the apps for macs would take advantage of GCD & OCL.
Click to expand...

You (and most other people) need to realize that there is a relatively small set of computations that can be accelerated by this kind of technology. Of course certain types of video, image, and sound processing will work, but your run-of-the-mill Mac app isn't going to be able to take advantage of GCD or OCL.
 
But of course developers will need to rework their apps, and I doubt that a lot of them are going to do that until they release another version.
 
Not sure if my Intel macPro can take advantage of this... what do you think?

My MacPro is one of those that can not boot to the 64 bit Kernal... but still runs 64 bit apps.. like LightRoom. Does this mean it can not take advantage of these advancements?:confused:
 
admanimal said:
You (and most other people) need to realize that there is a relatively small set of computations that can be accelerated by this kind of technology. Of course certain types of video, image, and sound processing will work, but your run-of-the-mill Mac app isn't going to be able to take advantage of GCD or OCL.
Click to expand...


Exactly, but right now FCP has more than 50 percent of the editing market share. Not a bad user group for this type of technology. Compressor needs multithreading badly! Qmaster is just a band aid.

This is where FCS falls short:
1. Rendering
2. Encoding
3. Real time vector effects

This technology will help all of these. :D
 
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