Apple: Next Mac OS X unlocks chip power

Snow Leopard features tech called Grand Central Dispatch to better tap into multicore chip power. Also: OpenCL for doing calculations on a graphics chip.

This story was corrected. See below for details.

SAN FRANCISCO--Apple wants Mac OS X to do a better job dealing with the new directions that Moore's Law has taken computer chips.

At its Apple Worldwide Developer Conference here, Bertrand Serlet, senior vice president of software engineering, shed light on technology called Grand Central Dispatch that's designed to make Mac OS X 10.6, called Snow Leopard, take better advantage of multicore processors and graphics processors.

Power play at Apple's WWDC 2009. James Martin/CNET

Computer chips for years improved in performance through faster clock speeds, but processor engineers ran into problems with chips consuming inordinate amounts of power and producing inordinate amounts of heat. In addition, the faster clock speeds sometimes meant chips just idled faster because memory access speeds couldn't keep up.

The new direction: multicore processors that put multiple processing engines on the same chip. The problem with the approach, though, is that PC software typically had been written to run with one thread of instructions at a time. Multicore processors work best when software does many things at the same time, which is much harder to program.

Grand Central Dispatch is designed to address that problem for software developers, making it easier to program multithreaded software, use operating system services, and tune program executions.

It also improves how Mac manages those threads, Serlet said. For example, when running Apple's Mail app, today's Leopard OS uses about the number of threads when busy as when idle.

"When it's busy, it uses more threads to take advantage of multicores. When idle, all those threads go away, giving back resources to the system," Serlet said. "When you apply that to every application, you get a big win in performance and responsiveness."

Graphics chip power
The new Mac OS X also is designed to support a programming technology called GPGPU--general-purpose graphics processing unit--which lets a graphics chip run some computing jobs in addition to its ordinary job displaying graphics.

To make its GPGPU technology work, Apple uses OpenCL, a C-like programming technology that has the support of graphics chipmakers Nvidia, AMD's ATI, Intel, and others.

Graphics chips aren't good for every sort of computing task, but they are good for mathematical calculations--including they physics calculations often needed in video games that simulate flowing fabrics, bouncing balls, and other real-world actions.

Mac OS X will be available in September with an upgrade price of $29, a big notch less expensive than the $129 price of earlier upgrades.

Apple also is working to support 64-bit x86 processors, now the prevailing standard. One big advantage of 64-bit processors is support for more than 4GB of memory; Serlet also touted faster mathematical processing such as the doubled speed of fast Fourier transforms.

Apple has been gradually making its operating system fully 64-bit. "Snow Leopard is final stage where all the major system applications are written in 64-bit mode," Serlet said.

Correction 6:13 a.m. PDT Tuesday: This story misidentified the speaker. It was Bertrand Serlet, senior vice president of software engineering.

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