A different take on SLI / MGPU: pipelining?

[Quartz]

Have AMD or Nvidia tried pipelining as a MGPU solution? That is, having different cards handle different parts of the render process in sequence.

For instance, if you have three cards, the first card could handle the basic t&l, then the second card could handle Hairworks, and the third could handle ray tracing, which would then be output to the monitor. This would negate the microstutter so prevalent in MGPU setups.

I remember that you used to be able to hand off PhysX to a separate card but that wasn't in a pipeline but call and return.

 

[Quartz]

This will be very difficult to achieve

Enlighten me.

 

[Quartz]

The bus link between cards is too slow for that.

Is it? The throughput of NVLink is 100 GB / sec and it's bidirectional, so you can simultaneously have 100 GB/s from card A to cvard B and 100 GB /sec from B to C. If you assume that all the cards have all the textures in VRAM, how much data actually needs to be transferred from card to card?

 

[Quartz]

I'm sorry but I'm still not seeing the problem. So long as the composited image gets to the next stage sufficiently quickly I don't see an issue. Nvlink has a bandwidth of 100GB / sec and the image data is going to be far less than 1 GB so you can transfer over 100 fps. Probably over 200. Remember that the textures are preloaded into all cards. So the added latency is very small.

 

[Quartz]

You aren't understanding how games are processed I think and it is beyond my ability to put it concisely into a post here

I'm well aware that there's much that cannot be separated out. But there are parts which can - RTX and Hairworks are two.