4 ms·

> yet GPUs don't support double precision well. Are there GPUs without FP64 functionality at all? Or are you just referring to most consumer GPUs being built f

> yet GPUs don't support double precision well. Are there GPUs without FP64 functionality at all? Or are you just referring to most consumer GPUs being built for FP32 performance over FP64?

Robadob 5y ago
It's not that GPUs don't support fp64, it's that for domestic gamer GPUs fp64 arithmetic is normally ~1:32 performance of fp32 arithmetic. e.g. 1080gtx FP16 (half) performance 138.6 GFLOPS (1:64) FP32 (float) performance 8.873 TFLOPS FP64 (double) performance 277.3 GFLOPS (1:32) e.g. 3090rtx FP16 (half) performance 35.58 TFLOPS (1:1) FP32 (float) performance 35.58 TFLOPS FP64 (double) performance 556.0 GFLOPS (1:64) Only generally 'tesla' class cards targeted at super computers have a 1:2 ratio (e.g. v100, A100, Titan V). Note, I believe Titan V is the only Titan series GPU with good double performance, as the Volta architecture was never available to Geforce GPUs. https://www.techpowerup.com/gpu-specs/geforce-gtx-1080.c2839 https://www.techpowerup.com/gpu-specs/geforce-gtx-1080.c2839 https://www.techpowerup.com/gpu-specs/geforce-rtx-3090.c3622 https://www.techpowerup.com/gpu-specs/geforce-rtx-3090.c3622 https://www.techpowerup.com/gpu-specs/tesla-v100-sxm3-32-gb.c3472 https://www.techpowerup.com/gpu-specs/tesla-v100-sxm3-32-gb.... https://www.techpowerup.com/gpu-specs/a100-sxm4-80-gb.c3746 https://www.techpowerup.com/gpu-specs/a100-sxm4-80-gb.c3746 https://www.techpowerup.com/gpu-specs/titan-v.c3051 https://www.techpowerup.com/gpu-specs/titan-v.c3051
- Const-me 5y ago
  For AMD GPUs the FP64/FP32 performance ratio is twice as high compared to nVidia, it’s 1:16 https://en.wikipedia.org/wiki/Radeon_RX_5000_series#Desktop https://en.wikipedia.org/wiki/Radeon_RX_5000_series#Desktop https://en.wikipedia.org/wiki/Radeon_RX_6000_series#Desktop https://en.wikipedia.org/wiki/Radeon_RX_6000_series#Desktop
modeless 5y ago
There are many GPUs with no double precision floating point support in hardware. Modern ones can probably emulate it. Older ones don't have any explicit support. Most real time 3D renderers do not use double precision at all.
- gbrown_ 5y ago
  > There are many GPUs with no double precision floating point support in hardware. Which ones? I'm genuinely curious about this.
  - modeless 5y ago
    I think all of the ones listed as DirectX 10.1 or lower on this page: https://en.wikipedia.org/wiki/Feature_levels_in_Direct3D https://en.wikipedia.org/wiki/Feature_levels_in_Direct3D Those are all quite old now of course, but even modern GPUs may not have 64-bit ALUs and rely on emulation instead. Intel Gen11 in Ice Lake, for example: https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-icllp-vol04-configurations_0.pdf https://01.org/sites/default/files/documentation/intel-gfx-p... In mobile architectures 64-bit ALUs can be an optional feature that is omitted for lower end configurations. I know this is true of PowerVR.
    - gbrown_ 5y ago
      Ah interesting to know about Gen11, thanks for the links.

> yet GPUs don't support double precision well. Are there GPUs without FP64 functionality at all? Or are you just referring to most consumer GPUs being built for FP32 performance over FP64?

Robadob 5y ago

It's not that GPUs don't support fp64, it's that for domestic gamer GPUs fp64 arithmetic is normally ~1:32 performance of fp32 arithmetic. e.g. 1080gtx FP16 (half) performance 138.6 GFLOPS (1:64) FP32 (float) performance 8.873 TFLOPS FP64 (double) performance 277.3 GFLOPS (1:32) e.g. 3090rtx FP16 (half) performance 35.58 TFLOPS (1:1) FP32 (float) performance 35.58 TFLOPS FP64 (double) performance 556.0 GFLOPS (1:64) Only generally 'tesla' class cards targeted at super computers have a 1:2 ratio (e.g. v100, A100, Titan V). Note, I believe Titan V is the only Titan series GPU with good double performance, as the Volta architecture was never available to Geforce GPUs. https://www.techpowerup.com/gpu-specs/geforce-gtx-1080.c2839 https://www.techpowerup.com/gpu-specs/geforce-gtx-1080.c2839 https://www.techpowerup.com/gpu-specs/geforce-rtx-3090.c3622 https://www.techpowerup.com/gpu-specs/geforce-rtx-3090.c3622 https://www.techpowerup.com/gpu-specs/tesla-v100-sxm3-32-gb.c3472 https://www.techpowerup.com/gpu-specs/tesla-v100-sxm3-32-gb.... https://www.techpowerup.com/gpu-specs/a100-sxm4-80-gb.c3746 https://www.techpowerup.com/gpu-specs/a100-sxm4-80-gb.c3746 https://www.techpowerup.com/gpu-specs/titan-v.c3051 https://www.techpowerup.com/gpu-specs/titan-v.c3051

Const-me 5y ago
For AMD GPUs the FP64/FP32 performance ratio is twice as high compared to nVidia, it’s 1:16 https://en.wikipedia.org/wiki/Radeon_RX_5000_series#Desktop https://en.wikipedia.org/wiki/Radeon_RX_5000_series#Desktop https://en.wikipedia.org/wiki/Radeon_RX_6000_series#Desktop https://en.wikipedia.org/wiki/Radeon_RX_6000_series#Desktop

modeless 5y ago

There are many GPUs with no double precision floating point support in hardware. Modern ones can probably emulate it. Older ones don't have any explicit support. Most real time 3D renderers do not use double precision at all.

gbrown_ 5y ago
> There are many GPUs with no double precision floating point support in hardware. Which ones? I'm genuinely curious about this.
- modeless 5y ago
  I think all of the ones listed as DirectX 10.1 or lower on this page: https://en.wikipedia.org/wiki/Feature_levels_in_Direct3D https://en.wikipedia.org/wiki/Feature_levels_in_Direct3D Those are all quite old now of course, but even modern GPUs may not have 64-bit ALUs and rely on emulation instead. Intel Gen11 in Ice Lake, for example: https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-icllp-vol04-configurations_0.pdf https://01.org/sites/default/files/documentation/intel-gfx-p... In mobile architectures 64-bit ALUs can be an optional feature that is omitted for lower end configurations. I know this is true of PowerVR.
  - gbrown_ 5y ago
    Ah interesting to know about Gen11, thanks for the links.