Thursday, September 1st 2022

Intel Details its Ray Tracing Architecture, Posts RT Performance Numbers

Intel on Thursday posted an article that dives deep into the ray tracing architecture of its Arc "Alchemist" GPUs, which are particularly relevant with performance-segment parts such as the Arc A770, which competes with the NVIDIA GeForce RTX 3060. In the article, Intel posted ray tracing performance numbers that put it at-par with, or faster than the RTX 3060, which which it has traditional raster performance parity. In theory, this would make Intel's ray tracing tech superior to that of AMD RDNA2, because while the AMD chips have raster performance parity, their ray tracing performance do not tend to be at par with NVIDIA parts at a price-segment level.

The Arc "Alchemist" GPUs meet the DirectX 12 Ultimate feature-set, and its ray tracing engine supports DXR 1.0, DXR 1.1, and Vulkan RT APIs. The Xe Core is the indivisible subunit of the GPU, and packs its main number-crunching machinery. Each Xe Core features a Thread Sorting Unit (TSU), and a Ray Tracing Unit (RTU). The TSU is responsible for scheduling work among the Xe Core and RTU, and is the core of Intel's "secret sauce." Each RTU has two ray traversal pipelines (fixed function hardware tasked with calculating ray intersections with intersections/BVH. The RTU can calculate 12 box intersections per cycle, 1 triangle intersection per cycle, and features a dedicated cache for BVH data.
The TSU, as we said, is the secret sauce of Intel's ray tracing performance. It's key to achieving what Intel calls "Asynchronous Ray Tracing." The TSU organizes ray tracing instructions and data such that rays with similar hit shaders are optimally allocated unified shader resources of the Xe cores, for the best possible allocation of hardware resources. The slide above details the ray tracing pipeline, where the TSU is shown playing a big role in optimizing things for the hit-shader execution stage.
Intel posted performance numbers for the Arc A770 at 1080p, compared with the RTX 3060 at the same resolution, across a selection of 17 games. These include Ghostwire Tokyo, which was earlier found to be extremely sub-optimal on the "Alchemist" architecture, but has since been optimized for in the latest beta drivers. The A770 trades blows with the RTX 3060, even if there are a few cases where the NVIDIA chip is slightly ahead. This is certainly a better showing when compared to a Radeon RX 6650 XT pitted against the RTX 3060 in ray tracing.
The A770 isn't meant for 1440p + Ray Tracing (nor is the RTX 3060), but performance enhancements like the XeSS and DLSS make both possible. While Intel didn't compare the A770+XeSS to RTX 3060+DLSS at 1440p, it posted a slide about how XeSS makes gaming with ray tracing more than playable at 1440p, across both its "balanced" and "performance" presets.

Below is the video presentation from Intel:
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30 Comments on Intel Details its Ray Tracing Architecture, Posts RT Performance Numbers

#26
AusWolf
nguyenYeah let forgo 2 decades of improvements in rasterization, sounds like a good idea.
Current hybrid RT solution actually offer the best of both rasterization and RT, unless you like to play simple looking path-traced games like Quake 2 RTX or Minecraft RTX
Rasterization will always be important, but there will come a time when adding more raster performance to next generations of GPUs will be unnecessary, as RT hardware will be advanced enough to do the whole scene. It's kind of like the way GPUs took over a big chunk of work from the CPU through hardware T&L. The same way, RT hardware will eventually take over as well. At that time, rasterization will be used for retro gaming, mostly. It will still be important, but secondary to RT.

I'm not saying that this is the present, but I can see such a future in maybe 10 years.
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#27
Cooe
"This is certainly a better showing when compared to a Radeon RX 6650 XT pitted against the RTX 3060 in ray tracing."

... Except it really isn't... When you remove the handful of pre-RDNA 2 titles designed solely from the ground up for Nvidia's RTX hardware (ala Control & Cyberpunk) the RX 6600/6650XT generally has EXTREMELY similar RT performance to the RTX 3060 in modern titles... Making it likely super similar to the ARC 750 in those more recent titles as well.

The perception that "AMD is MILES behind in RT!" instead of the actual reality of being slightly to moderately inferior in most cases (outside full path tracing, where yes, Nvidia has a significant lead) comes solely from the crap circumstances of Control & Cyberpunk (pre-RDNA 2 games built w/ significant direct help from Nvidia) being arguably the most commonly benched titles for "RT performance".
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#28
Luke357
Cooe"This is certainly a better showing when compared to a Radeon RX 6650 XT pitted against the RTX 3060 in ray tracing."

... Except it really isn't... When you remove the handful of pre-RDNA 2 titles designed solely from the ground up for Nvidia's RTX hardware (ala Control & Cyberpunk) the RX 6600/6650XT generally has EXTREMELY similar RT performance to the RTX 3060 in modern titles... Making it likely super similar to the ARC 750 in those more recent titles as well.

The perception that "AMD is MILES behind in RT!" instead of the actual reality of being slightly to moderately inferior in most cases (outside full path tracing, where yes, Nvidia has a significant lead) comes solely from the crap circumstances of Control & Cyberpunk (pre-RDNA 2 games built w/ significant direct help from Nvidia) being arguably the most commonly benched titles for "RT performance".
If the ray tracing for Control and Cyberpunk is so nVidia optimized then why does ARC have good RT performance in those games while Radeon does not?
Posted on Reply
#29
AusWolf
Luke357If the ray tracing for Control and Cyberpunk is so nVidia optimized then why does ARC have good RT performance in those games while Radeon does not?
This. Also, Control and Cyberpunk are the most benchmarked games because they are the most popular ones (and also examples where RT is implemented right).
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