NVIDIA Pascal’s Simultaneous Multi-Projection (SMP) Technology Tested – Big Performance Boost in iRacing With Multi-Monitor
NVIDIA Pascal graphics card were launched back in May along with a range of new graphics technologies. One of those new technologies is known as Simultaneous Multi-Projection or SMP in short. The tech allows massive performance increase in VR titles thanks to a dedicated engine in the Pascal core. With VR titles increasing day after day, SMP can prove to be a killer feature for Pascal based graphics cards.
NVIDIA SMP Technology on Pascal Cards Offers Leap in Graphics Performance in VR and Multi-Monitor Titles
Back during the GeForce 10 series launch, NVIDIA discussed SMP in much detail. SMP can allow faster geometry processing by enabling Pascal graphics cards to pass such data through 16 projections from a single view - point. It can also offset the viewpoint for stereo applications such as VR, allowing up to 32 projections. This single pass stereo feature, the geometry processing and projection for each eye can be done in one pass, speeding up GPU render time.
For instance, Oculus Rift can display a total of 4.2 MPixels but not all of it will be displayed per eye. SMP renders only 2.8 MPixels using a conservative preset which allows faster performance by displaying frames which are being seen. SMP also delivers 2 times the geometry processing by applying geometry before the picture is rendered. All of this leads to better performance figures with Pascal’s new and modern architecture design that is geared for VR and Multi-monitor gaming.
Lens Matched Shading
Uses Simultaneous Multi-Projection to provide substantial performance improvements in pixel shading. The feature improves upon Multi-res Shading by rendering to a surface that more closely approximates the lens corrected image that is output to the headset display. This avoids the performance cost of rendering many pixels that are discarded during the VR lens warp post-process.
Single Pass Stereo
Traditionally, VR requires submitting and tessellating the geometry in a scene twice, once for each eye. Simultaneous Multi-Projection streamlines this by allowing geometry to be shared across both eyes. The GPU takes the geometry, processes it once, then projects one viewport for each eye. This means the tessellation and vertex shading work is only processed once, reducing the GPU’s geometry workload by half.
SMP Offers Up To 20% Performance Boost on GeForce GTX 1080 Graphics Card
Computerbase performed some in-depth tests in iRacing, an online car simulator that supports NVIDIA SMP. While this title isn't VR enabled, it does support SMP in Multi-Monitor setups. Simultaneous Multi-Projection saves geometry processing time by having to process it across all monitors at once rather than individually. It helps save GPU resources and increases performance in such case.
The two graphics cards that were tested included the GeForce GTX 1080 and GeForce GTX 1060. The GTX 1080 got a good 20% increase in performance with anti-aliasing disabled. With AA enabled, the performance rose up to 17%. Similar gains were reported by Computerbase on the $249 US, GeForce GTX 1060 graphics card. Tests were performed on 5760 x 1080 resolution across three full-HD monitors.
While iRacing uses a very early implementation of SMP, it still does show a decent gain in performance. Once it matures, it can immensely help Pascal based cards perform better in VR and multi-monitor titles. There are also some minor fixes that NVIDIA plans to release for SMP support in the near future when more titles start using the new tech.