20170516 - Flops vs Display Mode


"I want to demo something at Resolution X and Frame Rate Y with a Z TFlop GPU, what kind of content should I be looking for?" This is my quick attemp to answer such questions in a universally understandable way based on objective numbers. All source numbers from Wikipedia.

The Metric
Kflop/pix
While resolution can help scale sharpness, visual quality of the scene roughly scales with the platforms flop/pixel ratio. Lets classify game consoles by spec flop/sec divided by a typical target shaded pixel/sec for the console.

platform               Gflop/s width height hz Gpix/s Kflop/pix
====================== ======= ===== ====== == ====== =========
Wii ..................    14.1   640    480 30   0.01       1.5
Xbox360 ..............     240  1280    720 30   0.03       8.7
PS4 ..................    1843  1920   1080 30   0.06      29.6
PS4 Pro (Checkerboard)    4198  1920   2160 30   0.12      33.7
Scorpio ..............    6000  3840   2160 30   0.25      24.1

The numbers suggest that {PS4, PS4 Pro, Scorpio} generation and updates will have similar overall visual quality thanks to added performance being soaked up to hit a new 4K marketing target.

The table shows three major visual quality levels {Wii, Xbox360, PS4}. Given those Kflop/pix ratios, lets cross with possible HDMI 2.1 display modes, and then compute the size of GPU (in Tflop/sec) required to hit the visual bar for a given mode. Note, there is no 8K at 60Hz in the table because HDMI 2.1 doesn't have the bandwidth for that for 4:4:4.

Wii-Like Experience

Likely this table is off for higher pix/s modes, and should be recomputed with ROP limits, but I'm letting that slide due to lack of time. Numbers suggest it is possible to hit a Wii-like experience using a current upper mid-range GPU at virtually any resolution and frame-rate for 4:4:4 color supported at HDMI 2.1. This assumes that the app uses Vulkan or DX12, properly threads to avoid being CPU-bound, and resorts to rendering techniques applicable to lower perf/pix machines (no giant deferred shading), etc.

width height  hz Tflop/s
===== ====== === =======
 1920 1080    30    0.09
 1920 1080    60    0.19
 1920 1080   120    0.37
 1920 1080   144    0.45
 1920 1080   240    0.75
===== ====== === =======
 2560 1440    30    0.17
 2560 1440    60    0.33
 2560 1440   120    0.66
 2560 1440   144    0.80
 2560 1440   240    1.33
===== ====== === =======
 3840 2160    30    0.37
 3840 2160    60    0.75
 3840 2160   120    1.49
 3840 2160   144    1.79
===== ====== === =======
 5120 2880    30    0.66
 5120 2880    60    1.33
 5120 2880   120    2.65
===== ====== === =======
 7680 4320    30    1.49
===== ====== === =======
10240 5760    30    2.65


Xbox360-Like Experience

Numbers suggest that a game with a visual target of last generation consoles would be the target for 4K displays when mixed with an ok frame rate like 60Hz, approaching a good frame rate like 120 Hz, on current higher-end GPUs.

width height  hz Tflop/s
===== ====== === =======
 1920 1080    30    0.54
 1920 1080    60    1.08
 1920 1080   120    2.16
 1920 1080   144    2.60
 1920 1080   240    4.33
===== ====== === =======
 2560 1440    30    0.96
 2560 1440    60    1.92
 2560 1440   120    3.85
 2560 1440   144    4.62
 2560 1440   240    7.70
===== ====== === =======
 3840 2160    30    2.16
 3840 2160    60    4.33
 3840 2160   120    8.66
 3840 2160   144   10.39
===== ====== === =======
 5120 2880    30    3.85
 5120 2880    60    7.70
 5120 2880   120   15.39
===== ====== === =======
 7680 4320    30    8.66
===== ====== === =======
10240 5760    30   15.39


PS4-Like Experience

Numbers suggest 4K at 60Hz is beyond the reach of current top-end GPUs for a PS4-like visual experience. E-sports 1080p at 240Hz targets would also be pre-PS4 visual quality targets.

width height  hz Tflop/s
===== ====== === =======
 1920 1080    30    1.84
 1920 1080    60    3.68
 1920 1080   120    7.37
 1920 1080   144    8.84
 1920 1080   240   14.73
===== ====== === =======
 2560 1440    30    3.27
 2560 1440    60    6.55
 2560 1440   120   13.09
 2560 1440   144   15.71
 2560 1440   240   26.19
===== ====== === =======
 3840 2160    30    7.37
 3840 2160    60   14.73
 3840 2160   120   29.46
 3840 2160   144   35.35
===== ====== === =======
 5120 2880    30   13.09
 5120 2880    60   26.19
 5120 2880   120   52.38
===== ====== === =======
 7680 4320    30   29.46
===== ====== === =======
10240 5760    30   52.38


Going Beyond a PS4-Like Experience

Chasing quadrupling resolutions has in some respects held visual quality at the 2005-2013 level of realism, just with sharper output. This section looks at moving to the step beyond where games are now. The difference between PS4 and Xbox360 is roughly a 3.4x bump in Kflop/pix, using that number, the next visual bump after PS4 is to reach the 101 Kflop/pix level. Numbers suggest that dropping resolution is the critical component to hit the next visual bar, so 540p and 720p have been included in the table. Numbers point out that for a border-line acceptable 60Hz target, even the 2.5K displays will likely be showing up-sampled content at the next visual bump. Also for this visual quality, 4K at 60Hz requires a GPU which is almost 6 times the performance of a FuryX.

width height  hz Tflop/s
===== ====== === =======
  960 540     30    1.57
  960 540     60    3.14
  960 540    120    6.29
  960 540    144    7.55
  960 540    240   12.58
===== ====== === =======
 1280 720     30    2.80
 1280 720     60    5.59
 1280 720    120   11.18
 1280 720    144   13.42
 1280 720    240   22.36
===== ====== === =======
 1920 1080    30    6.29
 1920 1080    60   12.58
 1920 1080   120   25.16 
 1920 1080   144   30.19
 1920 1080   240   50.31
===== ====== === =======
 2560 1440    30   11.18
 2560 1440    60   22.36
 2560 1440   120   44.72
 2560 1440   144   53.67
 2560 1440   240   89.45
===== ====== === =======
 3840 2160    30   25.16
 3840 2160    60   50.31
 3840 2160   120  100.63
 3840 2160   144  120.75
===== ====== === =======
 5120 2880    30   44.72
 5120 2880    60   89.45
 5120 2880   120  178.89
===== ====== === =======
 7680 4320    30  100.63
===== ====== === =======
10240 5760    30  178.89