A Small Line of Code Ended up Costing Intel GPUs A x100 Reduction In RT Performance

No I didn’t get the numbers wrong in the title!

Intel Linux GPU driver developers recently released an update for the Arc GPUs providing a boost of upto 100x in Raytracing performance. To think about it, where did that 100x loss in performance come from in the first place then. A difference of 100x is not something to take lightly, I mean wouldn’t you notice if you had 1$ instead of $100

Phoronix states that a fix was introduced into the open-source Intel Mesa Vulkan driver by Intel Linux graphics driver engineering stalwart Lionel Landwerlin. The comments made by the developer are rather interesting as he literally stated ‘Like a 100x (not joking) improvement’.  

Intel’s Apparent Failure in Drivers | Future

 So what went wrong? Well its not rocket science, and that’s a good thing. Originally, the Vulkan driver made sure that any memory required for Vulkan RT would be stored locally (on the very fast on-board memory). Even if you’re not a developer of any sort, you must know that fast equates to better, keep that in mind as it’ll come in handy.

Basically, everything was perfect apart from one line. They forgot to include the line which actually allocates the memory, rendering all their efforts null and void. What happened then? Well the Vulkan driver used the slower on-board memory causing the massive decreases in performance.

After setting a flag for “ANV_BO_ALLOC_LOCAL_MEM”, the Vulkan driver started to use the much faster on-board memory leading to the abovementioned 100x gain in performance. Mesa 22.2 containing the above mentioned code along with other improvements is expected to reach end-users by the last week of August.

This puts to show the importance of good drivers as just one line of code can lead to a massive increase of over 100x in performance. Intel has had its fair share of struggle with the driver optimization. Intel’s actual competitor was the RTX 3070 and leaked benchmarks show that it lies somewhere in the territory of the RTX 3070 although gaming performance varies.

 

 

Abdullah Faisal
With a love for computers since the age of give, Abdullah has always sought to delve into the depths of information, and uses it as his guiding light. He believes success is of utmost importance as history is written by the victor.