Intel fixes major Arc GPU driver issue with a single line of code

Anyone who’s ever dabbled in programming can tell you that a single mistake can have some very big consequences. So it is with one of the first drivers for Intel’s much-anticipated Arc desktop GPUs. According to an official merge request for the Linux version of one open source driver, a single line of code caused an error that resulted in a “100x” reduction in ray tracing performance. The error has been caught and merged into the next release.

Things get a little technical here. The error was spotted by Intel engineer Lionel Landwerlin and posted to the open Mesa gitlab repository. According to his notes, the previous version of the Vulkan ray tracing implementation used system memory (as in the main RAM connected to the motherboard) instead of local memory (the GDDR6 RAM soldered directly to the graphics card). Of course, speeding up graphics processing is the entire point of having memory on the graphics card in the first place, so this is kind of a big swing-and-a-miss in terms of any graphics driver.

With a change to a single line of code, Landwerlin reported “like a 100x (not joking) improvement” to ray tracing performance using Vulkan on Linux. Which isn’t surprising, since the driver’s now assigning tasks to the memory that’s actually designed to perform those tasks, instead of the much more general system RAM. The change has been approved and merged for the next Mesa driver release, as reported by Phoronix.

This little episode illustrates how Intel is trailing far behind its new competitors in the discrete graphics card markets. Nvidia and AMD have decades of experience in writing and tuning discrete graphics drivers, not just for PCs in general, but to tweak and improve performance for specific graphics APIs (and sometimes even individual games). It’s impossible to claim that the established industry giants wouldn’t have made the same mistake, especially since we’re talking about Linux here. But it’s easy to point to this single-line error as an example of Intel’s immaturity in terms of graphics drivers.

Some of Intel’s latest press messaging reflects this. The company is hoping an aggressive three-tier strategy with competitive pricing will help alleviate its poor optimization for some games as it enters the worldwide market, with a U.S. release planned for later this summer. Specifically, Arc GPUs will be priced to compete with similar graphics cards based on the lowest tier of performance it can achieve in popular games, not the highest.

All that being said, the fact that Intel could catch this issue long before the international release of its drivers is promising. While the company has a lot of catching up to do in this area, it is, you know, Intel. A multi-billion-dollar international megacorp can more or less buy its way into a new market if it wants to, though that doesn’t mean it will succeed. If Intel can keep up the pace with improvements to its software and development teams, we might be looking at a much more even race in the desktop GPU market after a year or two.