[osg-users] long waiting time between cull and draw

[Richard Harrison]

On 03/07/2019 21:47, Tomas Eilsoe wrote:
> We observe a large period of waiting between the cull and the draw calls, which seems weird. See attached pic.

I suspect that this is because of vsync; your frame rate is ~60hz which 
is likely the monitor frequency.

With my system (AMD R9-290) I only get the orange "GPU" sections when 
running with vsync; if I disable it (traits->vsync = false) then these 
disappear and more than 60hz is possible so I generally lock to 60hz 
application side by waiting the appropriate amount after rendering has 
finished.

I generally run with vsync disabled because it seems there is something 
about the AMD driver that causes a vsync wait between each camera; I 
wrote some notes about this 
http://chateau-logic.com/content/deferred-rendering-rembrandt-performance


> Anybody have a hint on how to debug this ?

Disable vsync and see what happens.