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Wtf does 80 Compute Units mean? I author shaders and write graphics software and don’t have the slightest clue why that’s in marketing materials. Why do I care?

Wtf does 80 Compute Units mean? I author shaders and write graphics software and don’t have the slightest clue why that’s in marketing materials. Why do I care? It can’t be the equivalent of a CUDA cores because Nvidia ships more than 80 of whatever those are in their cards, and AMD already calls theirs Stream Processors or some crap like that. Graphics hardware always has such worthless marketing. Downvoting on HN is so obnoxious, I wish someone would build a better platform. You can’t have an opinion about anything.

dathinab 5y ago
Kinda nothing. Different vendors (and potentially different cards of the same vendor) use different architectures which are segmented in different ways. > AMD already calls theirs Stream 3840 Steam processor for a W6800X, more for a W6900X But in the end only Benchmarks for your workload matter either way.
wmf 5y ago
For Nvidia each SM has 64 "cores" while for AMD each CU has 64 "cores".
- dogma1138 5y ago
  A CU is more equivalent to a GPC than to an SM tho with RDNA2 that’s also not exactly true as they introduced WGPs. NVIDIA and AMD hardware is quite different the “core” count comparison is pretty meaningless. An Ampere SM also has also quite a bit more than 64 cores.
mastazi 5y ago
Yeah there is no agreed upon terminology. I'm not an expert but I suspect that GPU architecture is very diverse compared to other types of processor architectures, so maybe the diverse terminology is not just because of marketing - but then again marketing is certainly a big factor.
gerardvivancos 5y ago
In AMD’s terms, a Compute Unit is roughly a grouping of Stream Processors. It has more stuff than the SPs and the exact configuration is different across architectures/generations If you’re interested in this particular GPU you’ll want to read the RDNA2 white paper [0] Regarding CUDA cores, the architecture that Nvidia uses is substantially different from AMD’s, but still there is a similar grouping where the CUDA cores live in groups called Streaming Multiprocessors. Which -as opposed to AMD’s CUs- do not include TMUs as far as I know so there’s another level of hierarchy called the TPC and then the GPC. There’s a great article [1] from Fabien Sanglard about Nvidia’s recent architectural history which you might find of interest It is hard to compare amounts of any of these things against each other because there’s no direct equivalence. They are simply different architectural approaches and while one could say that CUDA cores are equivalent in function to Stream Processors and be superficially right, there are too many important differences which make comparisons based on how many of them are available an apples to oranges comparison. It is even not straight forward to compare CUDA cores to CUDA cores or CUs to CUs across different generations. [0]: https://www.amd.com/system/files/documents/rdna-whitepaper.pdf https://www.amd.com/system/files/documents/rdna-whitepaper.p... [1]: https://fabiensanglard.net/cuda/ https://fabiensanglard.net/cuda/
systemvoltage 5y ago
80 compute units gets people going that are not technical. They'll just exclaim "80 compute units!? I am totally buying this". Also see MHz and Megapixel race. Ever wondered why Ryzen CPU boxes are fancy? Same concept. As far as people are gullible, marketing will continue to serve them. Let's educate the people from recognizing marketing non-sense. Only then things can improve. Barking at "worthless marketing" people is naive - they're doing exactly what the numbers are indicating. If they don't, product won't sell as much. They're literally doing their job. Blame the people but we don't like to confront that.
- gerardvivancos 5y ago
  To be fair, you can compare those 80 CUs to the Xbox Series X 52 CUs. Or to any other AMD’s RDNA2 GPU out there. You are going to need to know what’s the core frequency and other GPU specs to properly compare but it is not just marketing.
- kcb 5y ago
  It really isn't just marketing...each compute unit is a real functional separation of the GPU. The technical details of this are obviously unimportant to most consumers, but it's highly important to anyone programming against them.
  - dragontamer 5y ago
    Which makes the "CU" kind of ironic, because CUs haven't been used since Vega / GCN. The new unit is "WGP", which are twice the size of a former CU. An RDNA 40-WGP will be sold as 80-CU. Presumably, AMD marketing felt that CUs stuck enough in the market that they should have a period where they sell WGPs but call them CUs on marketing material.
dragontamer 5y ago
> Wtf does 80 Compute Units mean Same thing as "16-core CPU". A compute unit is the smallest unit of organization that contains what is necessary to take an instruction pointer, find an instruction, and move around the data between registers. A "Core" can be a dual-supersclice (from POWER9), or a quad-superslice (for the 8-thread per core POWER9), or really ambiguous (see Bulldozer). GPUs have more design freedom right now so different GPU makers have extremely different designs. > It can’t be the equivalent of a CUDA cores because Nvidia ships more than 80 of whatever those are in their cards NVidia calls them SM: streaming multiprocessors. They have a different design and different assembly language, and are therefore not comparable. No more can you compare an Apple M1 core vs an ARM Cortex A53 core, or a Xeon core or EPYC core. They are all different designs.
- deleted 5y ago
  [deleted]

dathinab 5y ago

Kinda nothing. Different vendors (and potentially different cards of the same vendor) use different architectures which are segmented in different ways. > AMD already calls theirs Stream 3840 Steam processor for a W6800X, more for a W6900X But in the end only Benchmarks for your workload matter either way.

wmf 5y ago

For Nvidia each SM has 64 "cores" while for AMD each CU has 64 "cores".

dogma1138 5y ago
A CU is more equivalent to a GPC than to an SM tho with RDNA2 that’s also not exactly true as they introduced WGPs. NVIDIA and AMD hardware is quite different the “core” count comparison is pretty meaningless. An Ampere SM also has also quite a bit more than 64 cores.

mastazi 5y ago

Yeah there is no agreed upon terminology. I'm not an expert but I suspect that GPU architecture is very diverse compared to other types of processor architectures, so maybe the diverse terminology is not just because of marketing - but then again marketing is certainly a big factor.

gerardvivancos 5y ago

In AMD’s terms, a Compute Unit is roughly a grouping of Stream Processors. It has more stuff than the SPs and the exact configuration is different across architectures/generations If you’re interested in this particular GPU you’ll want to read the RDNA2 white paper [0] Regarding CUDA cores, the architecture that Nvidia uses is substantially different from AMD’s, but still there is a similar grouping where the CUDA cores live in groups called Streaming Multiprocessors. Which -as opposed to AMD’s CUs- do not include TMUs as far as I know so there’s another level of hierarchy called the TPC and then the GPC. There’s a great article [1] from Fabien Sanglard about Nvidia’s recent architectural history which you might find of interest It is hard to compare amounts of any of these things against each other because there’s no direct equivalence. They are simply different architectural approaches and while one could say that CUDA cores are equivalent in function to Stream Processors and be superficially right, there are too many important differences which make comparisons based on how many of them are available an apples to oranges comparison. It is even not straight forward to compare CUDA cores to CUDA cores or CUs to CUs across different generations. [0]: https://www.amd.com/system/files/documents/rdna-whitepaper.pdf https://www.amd.com/system/files/documents/rdna-whitepaper.p... [1]: https://fabiensanglard.net/cuda/ https://fabiensanglard.net/cuda/

systemvoltage 5y ago

80 compute units gets people going that are not technical. They'll just exclaim "80 compute units!? I am totally buying this". Also see MHz and Megapixel race. Ever wondered why Ryzen CPU boxes are fancy? Same concept. As far as people are gullible, marketing will continue to serve them. Let's educate the people from recognizing marketing non-sense. Only then things can improve. Barking at "worthless marketing" people is naive - they're doing exactly what the numbers are indicating. If they don't, product won't sell as much. They're literally doing their job. Blame the people but we don't like to confront that.

gerardvivancos 5y ago
To be fair, you can compare those 80 CUs to the Xbox Series X 52 CUs. Or to any other AMD’s RDNA2 GPU out there. You are going to need to know what’s the core frequency and other GPU specs to properly compare but it is not just marketing.
kcb 5y ago
It really isn't just marketing...each compute unit is a real functional separation of the GPU. The technical details of this are obviously unimportant to most consumers, but it's highly important to anyone programming against them.
- dragontamer 5y ago
  Which makes the "CU" kind of ironic, because CUs haven't been used since Vega / GCN. The new unit is "WGP", which are twice the size of a former CU. An RDNA 40-WGP will be sold as 80-CU. Presumably, AMD marketing felt that CUs stuck enough in the market that they should have a period where they sell WGPs but call them CUs on marketing material.

dragontamer 5y ago

> Wtf does 80 Compute Units mean Same thing as "16-core CPU". A compute unit is the smallest unit of organization that contains what is necessary to take an instruction pointer, find an instruction, and move around the data between registers. A "Core" can be a dual-supersclice (from POWER9), or a quad-superslice (for the 8-thread per core POWER9), or really ambiguous (see Bulldozer). GPUs have more design freedom right now so different GPU makers have extremely different designs. > It can’t be the equivalent of a CUDA cores because Nvidia ships more than 80 of whatever those are in their cards NVidia calls them SM: streaming multiprocessors. They have a different design and different assembly language, and are therefore not comparable. No more can you compare an Apple M1 core vs an ARM Cortex A53 core, or a Xeon core or EPYC core. They are all different designs.

deleted 5y ago
[deleted]