CDNA (microarchitecture)

CDNA (Compute DNA) is a compute-centered graphics processing unit (GPU) microarchitecture designed by AMD for datacenters. Mostly used in the AMD Instinct line of data center graphics cards, CDNA is a successor to the Graphics Core Next (GCN) microarchitecture; the other successor being RDNA (Radeon DNA), a consumer graphics focused microarchitecture.

AMD CDNA

Release date	November 16, 2020 (3 years ago) (2020-11-16)
Designed by	AMD
Fabrication process	TSMC N7 TSMC N6 TSMC N5[1]
History
Predecessor	AMD FirePro
Variant	RDNA (consumer, professional)

The first generation of CDNA was announced on March 5th, 2020,^[2] and was featured in the AMD Instinct MI100, launched November 16th, 2020.^[3] This is CDNA 1's only produced product, manufactured on TSMC's N7 FinFET process.

The second iteration of the CDNA line implemented a multi-chip module (MCM) approach, differing from its predecessor's monolithic approach. Featured in the AMD Instinct MI250X and MI250, this MCM design used an elevated fanout bridge (EFB)^[4] to connect the dies. These two products were announced November 8th, 2021, and launched November 11th. The CDNA 2 line includes an additional latecomer using a monolithic design, the MI210.^[5] The MI250X and MI250 were the first AMD products to use the Open Compute Project (OCP)'s OCP Accelerator Module (OAM) socket form factor. Lower wattage PCIe versions are available.

The third iteration of CDNA switches to a MCM design utilizing different chiplets manufactured on multiple nodes. Currently consisting of the MI300X and MI300A, this product contains 15 unique dies and is connected with advanced 3D packaging techniques. The MI300 series was announced on January 5, 2023, and launched in H2 2023.

CDNA 1

AMD CDNA 1

Release date	November 16, 2020 (3 years ago) (2020-11-16)
Fabrication process	TSMC N7 (FinFET)
History
Predecessor	AMD FirePro
Successor	CDNA 2

The CDNA family consists of one die, named Arcturus. The die is 750 millimeters squared, contains 25.6 billion transistors and is manufactured on TSMC's N7 node.^[6] The Arcturus die possesses 120 compute units and a 4096-bit memory bus, connected to four HBM2 placements, giving the die 32 GB of memory, and just over 1200 GB/s of memory bandwidth. Compared to its predecessor, CDNA has removed all hardware related to graphics acceleration. This removal includes but is not limited to: graphics caches, tessellation hardware, render output units (ROPs), and the display engine. CDNA retains the VCN media engine for HEVC, H.264, and VP9 decoding.^[7] CDNA has also added dedicated matrix compute hardware, similar to those added in Nvidia's Volta Architecure.

Architecture

The 120 compute units (CUs) are organized into 4 asynchronous compute engines (ACEs), each ACE maintaining its own independent command execution and dispatch. At the CU level, CDNA compute units are organized similarly to GCN units. Each CU contains four SIMD16, that each execute their 64-thread wavefront (Wave64) over four cycles.

Memory system

CDNA has a 20% clock bump for the HBM, resulting in a roughly 200 GB/s bandwidth increase vs. Vega 20 (GCN 5.0). The die has a shared 4 MB L2 cache that puts out 2 KB per clock to the CUs. At the CU level, each CU has its own L1 cache, a local data store (LDS) with 64 KB per CU and a 4 KB global data store (GDS), shared by all CUs. This GDS can be used to store control data, reduction operations or act as a small global shared surface.^[7][8]

Experimental PIM implementation

In October 2022, Samsung demonstrated a Processing-In-Memory (PIM) specialized version of the MI100. In December 2022 Samsung showed off a cluster of 96 modified MI100s, boasting large increases in processing throughput for various workloads and significant reduction in power consumption.^[9]

Changes from GCN

The individual compute units remain highly similar to GCN but with the addition of 4 matrix units per CU. Support for more datatypes were added, with BF16, INT8 and INT4 being added.^[7] For an extensive list of operations utilizing the matrix units and new datatypes, please reference the CDNA ISA Reference Guide.

Products

Model (Code name)	Released	Architecture & fab	Transistors & die size	Core		Fillrate[a]		Processing power (TFLOPS)								Memory				TBP	Software interface	Physical interface
								Vector[a][b]			Matrix[a][b]
				Config[c]	Clock[a] (MHz)	Texture[d] (GT/s)	Pixel[e] (GP/s)	Half (FP16)	Single (FP32)	Double (FP64)	INT8	BF16	FP16	FP32	FP64	Bus type & width	Size (GB)	Clock (MT/s)	Bandwidth (GB/s)
AMD Instinct MI100 (Arcturus)[10][11]	Nov 16, 2020	CDNA TSMC N7	25.6×109 750 mm2	7680:480:- 120 CU	1000 1502	480 720.96	-		15.72 23.10	7.86 11.5	122.88 184.57	61.44 92.28	122.88 184.57	30.72 46.14	15.36 23.07	HBM2 4096-bit	32	2400	1228	300 W	PCIe 4.0 ×16	PCIe ×16

• v
• t
• e

1. Boost values (if available) are stated below the base value in italic.
2. Precision performance is calculated from the base (or boost) core clock speed based on a FMA operation.
3. Unified shaders : Texture mapping units : Render output units and Compute units (CU)
4. Texture fillrate is calculated as the number of texture mapping units multiplied by the base (or boost) core clock speed.
5. Pixel fillrate is calculated as the number of render output units multiplied by the base (or boost) core clock speed.

CDNA 2

AMD CDNA 2

Release date	November 8, 2021 (3 years ago) (2021-11-08)
Fabrication process	TSMC N6
History
Predecessor	CDNA 1
Successor	CDNA 3

Like CDNA, CDNA 2 also consists of one die, named Aldebaran. This die is estimated to be 790 millimeters squared, and contains 28 billion transistors while being manufactured on TSMC's N6 node.^[12] The Aldebaran die contains only 112 compute units, a 6.67% decrease from Arcturus. Like the previous generation, this die contains a 4096-bit memory bus, now using HBM2e with a doubling in capacity, up to 64 GB. The largest change in CDNA 2 is the ability for two dies to be placed on the same package. The MI250X consists of 2 Aldebaran dies, 220 CUs (110 per die) and 128 GB of HBM2e. These dies are connected with 4 Infinity Fabric links, and addressed as independent GPUs by the host system.^[13]

Architecture

The 112 CUs are organized similarly to CDNA, into 4 asynchronous compute engines, each with 28 CUs, instead of the prior generations 30. Like CDNA, each CU contains four SIMD16 units executing a 64-thread wavefront across 4 cycles. The 4 matrix engines and vector units have added support for full rate FP64, enabling significant uplift over the prior generation.^[14] CDNA 2 also revises multiple internal caches, doubling bandwidth across the board.

Memory system

The memory system in CDNA 2 sports across the board improvements. Starting with the move to HBM2e, doubling the quantity to 64 GB, and increasing bandwidth by roughly one third (from ~1200 GB/s to 1600 GB/s).^[13] At the cache level. Each GCD has a 16-way, 8 MB L2 cache that is partitioned into 32 slices. This cache puts out 4 KB per clock, 128 B per clock per slice, which is a doubling of the bandwidth from CDNA.^[13] Additionally, the 4 KB Global Data Store was removed.^[14] All caches, including the L2 and LDS have support added for FP64 data.

Interconnect

CDNA 2 brings forth the first product with multiple GPUs on the same package. The two GPU dies are connected by 4 Infinity Fabric links, with a total bidirectional bandwidth of 400 GB/s.^[14] Each die contains 8 Infinity Fabric links, each physically implemented with a 16-lane Infinity Link. When paired with an AMD processor, this will act as Infinity Fabric. if paired with any other x86 processor, this will fallback to 16 lanes of PCIe 4.0.^[14]

Changes from CDNA

The largest up front change is the additional of full rate FP64 support across all compute elements. This results in a 4x increase FP64 matrix calculations, with large increases in FP64 vector calculations.^[13] Additionally support for packed FP32 operations were added, with opcodes like 'V_PK_FMA_F32' and 'V_PK_MUL_F32'.^[15] Packed FP32 operations can enable up to 2x throughput, but do require code modification.^[13] As with CDNA, for further information on CDNA 2 operations, please reference the CDNA 2 ISA Reference Guide.

Products

CDNA 3

AMD CDNA 3

Release date	December 6, 2023 (11 months ago) (2023-12-06)
Fabrication process	TSMC N5 & N6
History
Predecessor	CDNA 2

Unlike its predecessors, CDNA 3 consists of multiple dies, used in a multi-chip system, similar to AMD's Zen 2, 3 and 4 line of products. The MI300 package is comparatively massive, with nine chiplets produced on 5 nm, placed on top of four 6 nm chiplets.^[16] This is all combined with 128 GB of HBM3, using eight HBM placements.^[17] This package contains an estimated 146 billion transistors. It comes in the form of the Instinct MI300X and MI300A, the latter being an APU. These products were launched on December 6, 2023.^[18]

Products

Product Comparisons

Model (Code name)	Release date	Architecture & fab	Transistors & die size	Core		Fillrate[a]		Vector Processing power[a][b] (TFLOPS)			Matrix Processing power[a][b] (TFLOPS)					Memory				TBP	Software Interface	Physical Interface
				Config[c]	Clock[a] (MHz)	Texture[d] (GT/s)	Pixel[e] (GP/s)	Half (FP16)	Single (FP32)	Double (FP64)	INT8	BF16	FP16	FP32	FP64	Bus type & width	Size (GB)	Clock (MT/s)	Bandwidth (GB/s)
Tesla V100 (PCIE) (GV100)[19][20]	May 10, 2017	Volta TSMC  12 nm	12.1×109 815 mm2	5120:320:128:640 80 SM	1370	438.4	175.36	28.06	14.03	7.01	N/A	N/A	N/A	112.23	N/A	HBM2 4096 bit	16 32	1750	900	250 W	PCIe 3.0 ×16	PCIe ×16
Tesla V100 (SXM) (GV100)[21][22]	May 10, 2017				1455	465.6	186.24	29.80	14.90	7.46	N/A	N/A	N/A	119.19	N/A					300 W	NVLINK	SXM2
Radeon Instinct MI50 (Vega 20)[23][24][25][26][27][28]	Nov 18, 2018	GCN 5 TSMC 7 nm	13.2×109 331 mm2	3840:240:64 60 CU	1450 1725	348.0 414.0	92.80 110.4	22.27 26.50	11.14 13.25	5.568 6.624	N/A	N/A	26.5	13.3	?	HBM2 4096-bit	16 32	2000	1024	300 W	PCIe 4.0 ×16	PCIe ×16
Radeon Instinct MI60 (Vega 20)[24][29][30][31]				4096:256:64 64 CU	1500 1800	384.0 460.8	96.00 115.2	24.58 29.49	12.29 14.75	6.144 7.373	N/A	N/A	32	16	?
Tesla A100 (PCIE) (GA100)[32] [33]	May 14, 2020	Ampere TSMC 7 nm	54.2×109 826 mm2	6912:432:-:432 108 SM	1065 1410	460.08 609.12	-	58.89 77.97	14.72 19.49	7.36 9.75	942.24 1247.47	235.56 311.87	235.56 311.87	117.78 155.93	14.72 19.49	HBM2 5120 bit	40 80	3186	2039	250 W	PCIe 4.0 ×16	PCIe ×16
Tesla A100 (SXM) (GA100))[34] [35]					1275 1410	550.80 609.12	-	70.50 77.97	17.63 19.49	8.81 9.75	1128.04 1247.47	282.01 311.87	282.01 311.87	141.00 155.93	17.63 19.49					400 W	NVLINK	SXM4
AMD Instinct MI100 (Arcturus)[36][37]	Nov 16, 2020	CDNA TSMC 7 nm	25.6×109 750 mm2	7860:480:-:480 120 CU	1000 1502	480 720.96	-	?	15.72 23.10	7.86 11.5	122.88 184.57	61.44 92.28	122.88 184.57	30.72 46.14	15.36 23.07	HBM2 4096-bit	32	2400	1228	300 W	PCIe 4.0 ×16	PCIe ×16
AMD Instinct MI250X (PCIE) (Aldebaran)	Nov 8, 2021	CDNA 2 TSMC 6 nm	58×109 1540 mm2	14080:880:-:880 220 CU
AMD Instinct MI250X (OAM) (Aldebaran)
Tesla H100 (PCIE) (GH100)	Mar 22, 2022	Hopper TSMC 4 nm	80×109 814 mm2
Tesla H100 (SXM) (GH100)

• v
• t
• e

1. Boost values (if available) are stated below the base value in italic.
2. Precision performance is calculated from the base (or boost) core clock speed based on a FMA operation.
3. Unified shaders : Texture mapping units : Render output units : AI accelerators and Compute units (CU) / Streaming multiprocessors (SM)
4. Texture fillrate is calculated as the number of texture mapping units multiplied by the base (or boost) core clock speed.
5. Pixel fillrate is calculated as the number of render output units multiplied by the base (or boost) core clock speed.

See also

• AMD Instinct
• Radeon Pro

References

1. Smith, Ryan (June 9, 2022). "AMD: Combining CDNA 3 and Zen 4 for MI300 Data Center APU in 2023". AnandTech. Retrieved December 20, 2022.
2. Smith, Ryan. "AMD Unveils CDNA GPU Architecture: A Dedicated GPU Architecture for Data Centers". www.anandtech.com. Retrieved September 20, 2022.
3. "GPU Database: AMD Radeon Instinct MI100". TechPowerUp. Retrieved September 20, 2022.
4. Smith, Ryan. "AMD Announces Instinct MI200 Accelerator Family: Taking Servers to Exascale and Beyond". www.anandtech.com. Retrieved September 21, 2022.
5. Smith, Ryan. "AMD Releases Instinct MI210 Accelerator: CDNA 2 On a PCIe Card". www.anandtech.com. Retrieved September 21, 2022.
6. Kennedy, Patrick (November 16, 2020). "AMD Instinct MI100 32GB CDNA GPU Launched". ServeTheHome. Retrieved September 22, 2022.
7. "AMD CDNA Whitepaper" (PDF). amd.com. March 5, 2020. Retrieved September 22, 2022.
8. ""AMD Instinct MI100" Instruction Set Architecture, Reference Guide" (PDF). developer.amd.com. December 14, 2020. Retrieved September 22, 2022.
9. Aaron Klotz (December 14, 2022). "Samsung Soups Up 96 AMD MI100 GPUs With Radical Computational Memory". Tom's Hardware. Retrieved December 23, 2022.
10. "AMD Instinct MI100 Brochure" (PDF). AMD. Retrieved December 25, 2022.
11. "AMD CDNA Whitepaper" (PDF). AMD. Retrieved December 25, 2022.
12. Anton Shilov (November 17, 2021). "AMD's Instinct MI250X OAM Card Pictured: Aldebaran's Massive Die Revealed". Tom's Hardware. Retrieved November 20, 2022.
13. "Hot Chips 34 – AMD's Instinct MI200 Architecture". Chips and Cheese. September 18, 2022. Retrieved November 10, 2022.
14. "INTRODUCING AMD CDNA™ 2 ARCHITECTURE" (PDF). AMD.com. Retrieved November 20, 2022.
15. ""AMD Instinct MI200" Instruction Set Architecture" (PDF). developer.amd.com. February 4, 2022. Retrieved October 11, 2022.
16. Smith, Ryan. "CES 2023: AMD Instinct MI300 Data Center APU Silicon In Hand - 146B Transistors, Shipping H2'23". www.anandtech.com. Retrieved January 22, 2023.
17. Paul Alcorn (January 5, 2023). "AMD Instinct MI300 Data Center APU Pictured Up Close: 13 Chiplets, 146 Billion Transistors". Tom's Hardware. Retrieved January 22, 2023.
18. Kennedy, Patrick (December 6, 2023). "AMD Instinct MI300X GPU and MI300A APUs Launched for AI Era". ServeTheHome. Retrieved April 15, 2024.
19. Oh, Nate (December 16, 2022). "Nvidia Formally Announced PCIe Tesla V100". AnandTech.
20. "NVIDIA Tesla V100 PCIe 16GB". TechPowerUp.
21. Smith, Ryan (December 19, 2022). "Nvidia Volta Unveiled". AnandTech.
22. "NVIDIA Tesla V100 SXM3 32GB". TechPowerUp.
23. Walton, Jarred (January 10, 2019). "Hands on with the AMD Radeon VII". PC Gamer.
24. "Next Horizon – David Wang Presentation" (PDF). AMD.
25. "AMD Radeon Instinct MI50 Accelerator (16GB)". AMD.
26. "AMD Radeon Instinct MI50 Accelerator (32GB)". AMD.
27. "AMD Radeon Instinct MI50 Datasheet" (PDF). AMD.
28. "AMD Radeon Instinct MI50 Specs". TechPowerUp. Retrieved May 27, 2022.
29. "Radeon Instinct MI60". AMD. Archived from the original on November 22, 2018. Retrieved May 27, 2022.
30. "AMD Radeon Instinct MI60 Datasheet" (PDF). AMD.
31. "AMD Radeon Instinct MI60 Specs". TechPowerUp. Retrieved May 27, 2022.
32. "Nvidia A100 Tensor Core GPU Archiecture" (PDF). Nvidia. Retrieved December 12, 2022.
33. "Nvidia A100 PCIE 80 GB Specs". TechPowerUp. Retrieved December 12, 2022.
34. "Nvidia A100 Tensor Core GPU Archiecture" (PDF). Nvidia. Retrieved December 12, 2022.
35. "Nvidia A100 SXM4 80 GB Specs". TechPowerUp. Retrieved December 12, 2022.
36. "AMD Instinct MI100 Brochure" (PDF). AMD. Retrieved December 25, 2022.
37. "AMD CDNA Whitepaper" (PDF). AMD. Retrieved December 25, 2022.

External links

• Official webpage
• AMD CDNA Architecture whitepaper
• AMD CDNA 2 Architecture whitepaper
• AMD CDNA 3 Architecture whitepaper