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nVidia Quadro frame locking.

Introduction

Frame locking multiple graphics cards (in separate computers) is a feature only supported for nVidia Quadro cards. Regular Geforce (consumer) cards lack the hardware to synchronize vertical sync.

Terms

To understand the frame locking process, here are a few terms used:

• Swap groups - a group of windows (on a single Quadro) which must swap in-sync.
• Swap barriers - a group of Quadro cards, which must swap in-sync.

Notice that normally, only one window is opened by Racer on a single PC.

Hardware setup

First connect the physical graphics cards (nVidia Quadro) to eachother using the supplied network cables. The documentation on the cards explain how to daisy-chain them together, and how to use nVidia Control Panel to determine a server and the client displays. This process is not explained further here.

Make sure the setup works by checking the LED colors on the back of the graphics cards (blinking yellow=server/output, blinking green=client/input).

Software setup

On the Racer side you need to make sure that the PC's are locked together. The settings are in racer.ini.

• Set resolution.vsync to 1. This turns on vertical sync for that PC.
• Set resolution.swap_group to 1. This makes the OpenGL window on the PC join the swap group (on that PC).
• Set resolution.swap_barrier to 1. This makes the PC join a barrier across multiple PC's.

Make sure these settings are the same for all Racer loads on all PC's.

Example of settings

Here is an extract of racer.ini with swap-synchronization across multiple PC's is turned on. The same settings must apply to all PC's that are connected.

resolution
{
...
  ; Vertical sync? 0=off (max framerate, the default), 1=sync to display frequency, >1=set interval
  vsync=1
  ; Frame lock? (0=disable, 1=enable) Only works on nVidia Quadro cards.
  frame_lock=0
  ; Force frame lock enable/disable to succeed? (for tests on non-Quadro cards)
  frame_lock_force=0
  ; Swap group & barrier; for locking multiple computers/displays (nVidia Quadro cards only) - 0=off
  swap_group=1
  swap_barrier=1
}

(last updated February 21, 2013 )