โ11-13-2015 11:55 AM
โ11-13-2015 04:49 PM
โ11-13-2015 05:25 PM
โ11-21-2015 01:59 PM
โ11-21-2015 03:47 PM
"BalorNG" wrote:
Otherwise, I think I can expect pretty much 2x scaling with two GPUs due to VR SLI, right?
โ11-24-2015 11:26 AM
"kojack" wrote:"BalorNG" wrote:
Otherwise, I think I can expect pretty much 2x scaling with two GPUs due to VR SLI, right?
VR SLI requires programs to be specifically written for it. No existing rift software would support it. Future stuff might, depending on the engine they use.
โ11-24-2015 12:04 PM
"LogicalIncrements" wrote:
Why is VR SLI support not more common yet? To a general audience non-developer like myself, SLI support seems like a no-brainer for VR. I'd love to better understand the complexities behind accomplishing that, if you can point me to anything.
โ11-25-2015 12:38 AM
โ11-25-2015 06:19 AM
โ11-25-2015 05:19 PM
"MichaelNikelsky" wrote:
VR SLI is quite different from normal AFR-SLI. AFR-SLI does not work with VR or any application that requires a sync-point.
The way AFR-SLI works is by emitting all the commands to render a frame to one GPU and as soon as all the commands are emitted it switches to the next GPU for the next frame. If you introduce a sync-point, like it is done for VR to control latency, you would basically wait for the first GPU to finish rendering the frame before continuing with the next frame. This makes AFR-SLI pretty useless since the first GPU is idle after that anyways so you donยดt need to use the second GPU at all. Even when managing to render the first eye on one GPU and the second eye on the other GPU you would still be limited by the syncing since you need to wait for the second GPU to finish rendering. However, not using syncing is even worse since you might end up with different frames displayed on the left and right eye.
VR-SLI works (assumingly) completely different since it basically sents the rendering commands to both GPUs in parallel and just gives them different viewports/cameras/what ever you call it. This works even when using sync-points (although I would argue that it is not longer necessary).But unlike AFR-SLI, which pretty much works without doing anything in the application (unless the application does something stupid of course...) the application needs to be aware of the VR-SLI feature so it only does one rendering pass for both eyes and feed the GPU with all the necessary buffers.
Hope this makes it a bit clearer.