Snow Leopard Preview: Snow Leopard packs a great deal of new technology under its hood. In this look at Snow Leopard technologies, we examine OpenCL, a method for your Mac to make better use of your graphics card’s GPUs (Graphics Processing Units).
OpenCL Background
OpenCL (Open Computing Language) was originally developed by Apple to address a concern it had about accessing and using the many GPUs contained in today’s high-performance graphics processors. For example, the NVIDIA GeForce GTX 285, which was recently released for the Mac, contains 240 processor cores. Even basics graphics cards routinely contain multiple processor cores. Most of the time, the processors just hang around, doing nothing.
The processors are idle because the graphics engine usually isn’t doing much. Sure, it chugs away when performing complex vector math computations to create stunning graphics, such as the detailed characters and backgrounds in games or the complex images in computer animation that are based on calculating the physics of how light reflects off various objects. But pull up your word processor or web browser, and your graphics card just yawns.
In the past, each graphics chip manufacturer used its own language and methods to make use of all the GPUs on graphics cards. If software developers wanted to use the extra horsepower, they had to write to a specific card’s hardware, which meant supporting multiple versions of code, depending on which graphics card was present. OpenCL changed everything.
OpenCL
When Apple created OpenCL, its intent was to create a single framework that would allow developers to write programs that could be executed on any available processing unit within a computer. This could be the main processor of a computer, the GPUs on a graphics card, or any other type of appropriate processor that may be available.
Most importantly, unlike some of the other languages used to control a graphics processor, OpenCL extends the capabilities beyond graphics, allowing the GPUs to be used almost like general-purpose processors.
Apple, Intel, AMD, and NVIDIA worked together to produce the first OpenCL technical specification, which was then given to the Khronos Compute Working Group, to oversee as a computing standard and to further develop.
OpenCL And Snow Leopard
When it’s released in September, Snow Leopard will include Apple’s implementation of OpenCL 1.0, and will directly support ATI Radeon 4850 and 4870 graphics cards, as well as NVIDIA GeForce 9600M GT, 8800 GT, 8800 GTS, 9400M, 9600M GT, GT 120, and GT 130 graphics processors.
The first set of graphics processors that Snow Leopard supports encompass the graphics offerings that were available for Macs over the last two years. There are earlier graphics cards from NVIDIA and ATI that may be OpenCL capable, but it will require both the manufacturers and Apple to release new OpenCL drivers, which may not occur. Most of the companies involved are looking to current and future graphics processors, rather than bringing the drivers for older models up to date.
OpenCL and You
Snow Leopard and OpenCL won’t magically cause your current applications to start making use of the available GPUs. Instead, applications will have to be written to take advantage of OpenCL and all that available GPU horsepower that’s just idling away. OpenCL will probably see use in graphics applications, multimedia editing, CAD and 3D rendering, modeling, and simulation applications.
The importance of OpenCL, especially when combined with Grand Central Dispatch, another Snow Leopard technology, is that it makes Snow Leopard an ideal platform for developing state-of-the-art scientific, multimedia, modeling, graphics, and game applications. Even if your word processor and web browser never see a direct benefit from OpenCL, its capabilities, along with other Snow Leopard goodies, may inspire developers to bring new ideas and new applications over to the Mac. And that’s good for everyone.
