AMD's Upcoming Radeon RX 6600 RDNA 2 GPU To Feature 32MB Of Infinity Cache
A recent patch for Linux issued by AMD essentially confirms that the rumored Radeon RX 6600 will have a third of the amount of Infinity Cache as the already-launched Radeon RX 6700 XT. How this ends up affecting real-world performance obviously remains to be seen, but it is an interesting revelation all the same.
What exactly is Infinity Cache, and should you care? This is a part of AMD's second-generation Radeon DNA (RDNA 2) architecture. AMD introduced a new cache hierarchy with RDNA 2, injecting its latest GPUs with a pool of fast cache. Here's a look...
We got our first look at this with the Radeon RX 6800 series. Both the Radeon RX 6800 XT and Radeon RX 6800, powered by AMD's Navi 21 GPU (Navi 21 XT and Navi 21 XL, respectively), feature 128MB of Infinity Cache and a 256-bit memory bus. Coupled with 16Gbps GDDR6 memory chips, AMD says the implementation of Infinity Cache on those cards increases their native 512GB/s of native bandwidth all the way to 1,664GB/s (effective).
The same goes for AMD's flagship Radeon RX 6900 XT, based on AMD's Navi 21 XTX GPU—it too sports 128MB of Infinity Cache, 16Gbps GDDR6 memory chips, and a 256-bit memory bus. In short, Infinity Cache allows AMD to offer higher memory bandwidth on its graphics cards without resorting to a more expensive 512-bit memory bus, or pricier GDDR6X chips.
Linux Patch Reveals AMD's Radeon RX 6600 Will Ship With 32MB Of Infinity Cache
Our primer on Infinity Cache out of the way, let's talk about the Radeon RX 6600. In a recently issued patch for AMKFD, the Linux kernel HSA (Heterogeneous System Architecture) driver for AMD's processors with integrated graphics, AMD revealed some interesting tidbits about the cache arrangement for various GPUs.
"The L1 cache information has been updated and the L2/L3 information has been added. The changes have been made for Vega10 and newer ASICs. There are no changes for the older ASICs before Vega10," an AMD employee wrote.
Here's a look at the relevant patch notes...
Click to Enlarge (Source: Freedesktop.org)
To understand what we're looking at, let's break down the codenames at the top...
- Sienna Cichlid: Navi 21 (Radeon RX 6900/6800 series)
- Navy Flounder: Navi 22 (Radeon RX 6700 series)
- Dimgrey Cavefish: Navi 23 (Radeon RX 6600 series?)
The patch notes correctly show 128MB of Infinity Cache tied to Navi 21 (Radeon RX 6900 and 6800 series) and 96MB of Infinity Cache tied with Navi 22 (Radeon RX 6700 series). Then on the far right, we see Navi 23 sporting 32MB of Infinity Cache. This is believed to be what the Radeon RX 6600 will be powered by, whenever it launches. Note that these entries are labeled as "L3 cache," and not specifically "Infinity Cache" (though that's basically what it is).
So there you have it—that is about as close to official confirmation as there can be, short of an actual product launch or overt announcement. In this case, the revelation comes by way of Mike Li, who according to his LinkedIn profile, is a senior software development engineer at AMD.
