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Mantle allows VRAM to be combined from all cards installed

This is nothing new, developers will tell you AFR is by far more preferable which is why all but CivBE use it. A top down TBS.


In fact Johan from DICE will tell you the same thing. I'd like for it to be a bigger song and dance than it actually is, but the fact is there is no scaling to be found with SFR
 
Gregster said:
Just because a game uses SFR, it doesn't make it use the memory of each card and allow it to stack.
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Thats what Split Frame Rendering is, each GPU handles one half of the screen independently.

Instead of two GPU's rendering the full image through the master Memory pool the image is split in half with each GPU rendering one half.

The former is two GPU's acting as one, like one big GPU. hence the doubling of performance, the latter is two GPU's working independently on the same task, less performance but lower latency.

There is no "Stacking" of the Memory, it's a side effect of the GPU's still being independent of eachother and having their own buffer.

Stacking is also the wrong word for what you are describing, "Stacking" is more a kin to traditional Multi-GPU.

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It seems BF4 is also capable of it.

45 MULTI-GPU  Multi-GPU alternatives: – AFR – Alternate Frame Rendering (1-4 GPUs of the same power) – Heterogeneous AFR – 1 small + 1 big GPU (APU + Discrete) – SFR – Split Frame Rendering – Multi-GPU Job Graph – Primary strong GPU + slave GPUs helping  Frostbite supports AFR natively – No synchronization points within the frame – For resources that are not rendered every frame: re-render resources for each GPU  Example: sky envmap update on weather change  With Mantle multi-GPU is explicit and we have to build support for it ourselves
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http://www.slideshare.net/DICEStudio/rendering-battlefield-4-with-mantle
 
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The problem with split frame rendering - it works very well for say a top down game but in a lot of games you end up with 1 or more GPUs spending a lot of time doing not much more than rendering the skybox (completely wasting their performance) and other GPUs bogged down trying to render the more complex parts of the scene. You can up the "intelligence" of the way the scene is split up but that leads to more issues (beyond the scope of a single post).

There is a reason why AFR type techniques are prevalently used with most games.
 
humbug said:
Thats what Split Frame Rendering is, each GPU handles one half of the screen independently.

Instead of two GPU's rendering the full image through the master Memory pool the image is split in half with each GPU rendering one half.

The former is two GPU's acting as one, like one big GPU. hence the doubling of performance, the latter is two GPU's working independently on the same task, less performance but lower latency.

There is no "Stacking" of the Memory, it's a side effect of the GPU's still being independent of eachother and having their own buffer.

Stacking is also the wrong word for what you are describing, "Stacking" is more a kin to traditional Multi-GPU.

------

It seems BF4 is also capable of it.

http://www.slideshare.net/DICEStudio/rendering-battlefield-4-with-mantle
Click to expand...

nVidia have been doing SFR for a long time but the VRAM doesn't stack. You are reading too much into it and whilst it is possible to stack VRAM, it hasn't happened yet, as AMD would be singing it from the rooftops.
 
Gregster said:
nVidia have been doing SFR for a long time but the VRAM doesn't stack. You are reading too much into it and whilst it is possible to stack VRAM, it hasn't happened yet, as AMD would be singing it from the rooftops.
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They haven't managed to get it to work, they don't even officially support it.

It has happened, CiV BE uses it.
 
humbug said:
Really? why is that?

BTW, AFR is not what you think. it's a form of Hybrid CF. Like CF with different types of GPU. there is nothing "preferable" about it
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No form of Alternate frame rendering supports memory scaling. Heterogeneous AFR included.

Asynchronous Crossfire or SFR use sub GPU as slaves thus there is little performance scaling. Don't you think that if there were, there would be more than a top down turn based strategy game using it to demo Mantle?

Not sure what point you are trying to make Humbug. People would like memory scaling, unfortunately the performance just isn't there.
 
humbug said:
They haven't managed to get it to work, they don't even officially support it.

It has happened, CiV BE uses it.
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SFR has been working fine for SLI for a long time (memory pooling aside which is another story) it just isn't very useful for a lot of games.
 
For Work Station GP solution's, not gaming ^^^^^

Silent_Scone said:
No form of Alternate frame rendering supports memory scaling. Heterogeneous AFR included.

Asynchronous Crossfire or SFR use sub GPU as slaves thus there is little performance scaling. Don't you think that if there were, there would be more than a top down turn based strategy game using it to demo Mantle?

Not sure what point you are trying to make Humbug. People would like memory scaling, unfortunately the performance just isn't there.
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All i did was correct the premise that SFR would never be used and all hell broke lose.
 
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