NVIDIA Challenges AMD's Claims Concerning PhysX

As the latest episode in the long series of barbs traded by NVIDIA and AMD, the latter, in an interview with Bit-tech, accused the former of having deliberately removed multi-core CPU optimizations from its PhysX technology. The Worldwide Developer Relations Manager from Advanced Micro Devices, Richard Huddy, said that the PhysX technology had much a better multi-core support before Ageia, the original PhysX developer, was bough by NVIDIA.

“All these CPU cores we have are under-utilised and I'm going to take another pop at Nvidia here. When they bought Ageia, they had a fairly respectable multi-core implementation of PhysX. If you look at it now it basically runs predominantly on one, or at most, two cores,” Huddy said. “It's the same thing as Intel's old compiler tricks that it used to do; Nvidia simply takes out all the multi-core optimizations in PhysX.”

Tom's Hardware contacted NVIDIA for a reply and the GPU maker responded by completely denying the allegations. Nadeem Mohammad, PhysX director of product management, said that no such change had been done to the SDK code and that the “pop at NVIDIA” was “yet another completely unsubstantiated accusation made by an employee of one of our competitors.”

“I have been a member of the PhysX team, first with AGEIA, and then with Nvidia, and I can honestly say that since the merger with Nvidia there have been no changes to the SDK code which purposely reduces the software performance of PhysX or its use of CPU multi-cores,” Mohammad said.

“Our PhysX SDK API is designed such that thread control is done explicitly by the application developer, not by the SDK functions themselves. One of the best examples is 3DMarkVantage, which can use 12 threads while running in software-only PhysX. This can easily be tested by anyone with a multi-core CPU system and a PhysX-capable GeForce GPU. This level of multi-core support and programming methodology has not changed since day one. And to anticipate another ridiculous claim, it would be nonsense to say we ‘tuned’ PhysX multi-core support for this case.”

Mohammad went on to add that they were continuing to develop PhysX as a cross-platform solution and that any improvements made were meant to better its support on all platforms. NVIDIA's SDK tools are available not just for PCs and Xbox 360 devices, but also for the PS3, Wii and even the iPhone through one of its partners.

Mr. Nadeem Mohammad concluded by saying that, “Nvidia PhysX fully supports multi-core CPUs and multithreaded applications, period. Our developer tools allow developers to design their use of PhysX in PC games to take full advantage of multi-core CPUs and to fully use the multithreaded capabilities.”