Pascal (microarchitecture)

Nvidia Pascal

The GTX 1070, the second commercial card to use the Pascal architecture
Fabrication process 16 nm
History
Predecessor Maxwell
Successor Volta

Pascal is the codename for a GPU microarchitecture developed by Nvidia as the successor to the Maxwell microarchitecture. The Pascal microarchitecture was introduced April 2016 with the GP100 chip. The architecture is named after Blaise Pascal, the 17th century mathematician.

Details

On May 27, 2016 the GP104 chip to be found on the GeForce GTX 10XX branded graphics cards. Graphics cards are part of the GeForce 10 series.

In March 2014, Nvidia announced that the successor to Maxwell would be the Pascal microarchitecture; announced on the 6th May 2016 and released on the 27th May 2016. The Tesla P100 (GP100 chip) has a different version of the Pascal architecture compared to the GTX GPUs (GP104 chip). The shader units in GP104 have a rather Maxwell-like design.[1]

Architectural improvements of the GP100 architecture include the following:[2][3][4]

Architectural improvements of the GP104 architecture include the following:[1]

Overview

Graphics Processor Cluster

A chip is partitioned into Graphics Processor Clusters (GPCs). For the GP104 chips, a GPC engulfs 5 SMs.

Streaming Multiprocessor "Pascal"

A "Streaming Multiprocessor" corresponds to AMD's Compute Unit. An SMP encompasses 128 single-precision ALUs ("CUDA cores") on GP104 chips and 64 single-precision ALUs on GP100 chips.

What AMD calls a CU (compute unit) can be compared to what Nvidia calls an SM (streaming multiprocessor). While all CU versions consist of 64 shader processors (i.e. 4 SIMD Vector Units (each 16-lane wide)= 64), Nvidia (regularly calling shader processors "CUDA cores") experimented with very different numbers:

Polymorph-Engine 4.0

The Polymorph Engine version 4.0 is the unit responsible for Tessellation. It corresponds functionally with AMD's Geometric Processor. It has been moved from the shader module to the TPC to allow one Polymorph engine to feed multiple SMs within the TPC.[16]

Chips

On the GP104 chip an SM consists of 128 single-precision ALUs ("CUDA cores"), on the GP100 of 64 single-precision ALUs. Due to different organization of the chips, like number of double precision ALUs, the theoretical double precision performance of the GP100 is half of the theoretical one for single precision; the ratio is 1/32 for the GP104 chip.

Caption: Comparison table of some Kepler, Maxwell, and Pascal chips
GK104 GK110 GM204 (GTX 970) GM204 (GTX 980) GM200 GP104 GP100
Dedicated texture cache per SM 48 KiB N/A N/A N/A N/A N/A N/A
Texture (graphics or compute) or read-only data (compute only) cache per SM N/A 48 KiB[24] N/A N/A N/A N/A N/A
Programmer-selectable shared memory/L1 partitions per SM 48 KiB shared memory + 16 KiB L1 cache (default)[25] 48 KiB shared memory + 16 KiB L1 cache (default)[25] N/A N/A N/A N/A N/A
32 KiB shared memory + 32 KiB L1 cache[25] 32 KiB shared memory + 32 KiB L1 cache[25]
16 KiB shared memory + 48 KiB L1 cache[25] 16 KiB shared memory + 48 KiB L1 cache[25]
Unified L1 cache/texture cache per SM N/A N/A 48 KiB[26] 48 KiB[26] 48 KiB[26] 48 KiB[26] 24 KiB[26]
Dedicated shared memory per SM N/A N/A 96 KiB[26] 96 KiB[26] 96 KiB[26] 96 KiB[26] 64 KiB[26]
L2 cache per chip 512 KiB[26] 1536 KiB[26] 1792 KiB[27] 2048 KiB[27] 2048 KiB[26] 2048 KiB[26] 4096 KiB[26]

Performance

The theoretical single-precision processing power of a Pascal GPU in GFLOPS is computed as 2 (operations per FMA instruction per CUDA core per cycle) × number of CUDA cores × core clock speed (in GHz).

The theoretical double-precision processing power of a Pascal GPU is 1/2 of the single precision performance on GP100, and 1/32 on GP102 and GP104.

The theoretical half-precision processing power of a Pascal GPU is 2× of the single precision performance on GP100[8] and 1/64 on GP104.[15]

Successor

After Pascal, the next architecture will be preliminary codenamed Volta.[28] Nvidia announced that the Volta GPU would feature High Bandwidth Memory, Unified Memory, and NVLink.[28]

See also

References

  1. 1 2 "NVIDIA GeForce GTX 1080" (PDF). International.download.nvidia.com. Retrieved 2016-09-15.
  2. Gupta, Sumit (2014-03-21). "NVIDIA Updates GPU Roadmap; Announces Pascal". Blogs.nvidia.com. Retrieved 2014-03-25.
  3. "Parallel Forall". NVIDIA Developer Zone. Devblogs.nvidia.com. Retrieved 2014-03-25.
  4. "NVIDIA Tesla P100" (PDF). International.download.nvidia.com. Retrieved 2016-09-15.
  5. "nside Pascal: NVIDIA's Newest Computing Platform". 2016-04-05.
  6. Denis Foley (2014-03-25). "NVLink, Pascal and Stacked Memory: Feeding the Appetite for Big Data". nvidia.com. Retrieved 2014-07-07.
  7. "NVIDIA's Next-Gen Pascal GPU Architecture to Provide upto 10X Speedup for Deep Learning Apps". The Official NVIDIA Blog. Retrieved 23 March 2015.
  8. 1 2 Smith, Ryan (2015-04-05). "NVIDIA Announces Tesla P100 Accelerator - Pascal GP100 Power for HPC". AnandTech. Retrieved 2016-05-27. Each of those SMs also contains 32 FP64 CUDA cores - giving us the 1/2 rate for FP64 - and new to the Pascal architecture is the ability to pack 2 FP16 operations inside a single FP32 CUDA core under the right circumstances
  9. 1 2 3 Smith, Ryan (July 20, 2016). "The NVIDIA GeForce GTX 1080 & GTX 1070 Founders Editions Review: Kicking Off the FinFET Generation". AnandTech. p. 9. Retrieved July 21, 2016.
  10. 1 2 3 4 5 Smith, Ryan (July 20, 2016). "The NVIDIA GeForce GTX 1080 & GTX 1070 Founders Editions Review: Kicking Off the FinFET Generation". AnandTech. p. 10. Retrieved July 21, 2016.
  11. "GTX 1080 Graphics Card". GeForce. Retrieved 2016-09-15.
  12. Carbotte, Kevin (2016-05-17). "Nvidia GeForce GTX 1080 Simultaneous Multi-Projection & Async Compute". Tomshardware.com. Retrieved 2016-09-15.
  13. "Nvidia Pascal HDCP 2.2". Nvidia Hardware Page. Retrieved 2016-05-08.
  14. Shrout, Ryan (July 14, 2016). "3DMark Time Spy: Looking at DX12 Asynchronous Compute Performance". PC Perspective. Retrieved July 14, 2016.
  15. 1 2 Smith, Ryan (July 20, 2016). "The NVIDIA GeForce GTX 1080 & GTX 1070 Founders Editions Review: Kicking Off the FinFET Generation". AnandTech. p. 5. Retrieved July 21, 2016.
  16. Smith, Ryan (July 20, 2016). "The NVIDIA GeForce GTX 1080 & GTX 1070 Founders Editions Review: Kicking Off the FinFET Generation". AnandTech. p. 4. Retrieved July 21, 2016.
  17. Harris, Mark (April 5, 2016). "Inside Pascal: NVIDIA's Newest Computing Platform". Parallel Forall. Nvidia. Retrieved June 3, 2016.
  18. "NVIDIA TITAN X Graphics Card with Pascal". GeForce. Retrieved 2016-09-15.
  19. "New Quadro Graphics Built on Pascal Architecture". NVIDIA. Retrieved 2016-09-15.
  20. "Accelerating Data Center Workloads with GPUs". NVIDIA. Retrieved 2016-09-15.
  21. "NVIDIA GeForce GTX 1060 to be released on July 7th". VideoCardz.com. Retrieved 2016-09-15.
  22. "GTX 1060 Graphics Cards". GeForce. Retrieved 2016-09-15.
  23. "AIDA64 - Ever wondered how big the new #nVIDIA #Pascal GPU...". May 25, 2016. Retrieved June 5, 2016.
  24. Smith, Ryan (November 12, 2012). "NVIDIA Launches Tesla K20 & K20X: GK110 Arrives At Last". AnandTech. p. 3. Retrieved July 24, 2016.
  25. 1 2 3 4 5 6 Nvidia (September 1, 2015). "CUDA C Programming Guide". Retrieved July 24, 2016.
  26. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Triolet, Damien (May 24, 2016). "Nvidia GeForce GTX 1080, le premier GPU 16nm en test !". Hardware.fr (in French). p. 2. Retrieved July 24, 2016.
  27. 1 2 Smith, Ryan (January 26, 2015). "GeForce GTX 970: Correcting The Specs & Exploring Memory Allocation". AnandTech. p. 1. Retrieved July 24, 2016.
  28. 1 2 "NVIDIA Updates GPU Roadmap; Announces Pascal". The Official NVIDIA Blog.
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