Max buffered frames in OpenGL
Posted: 30 Mar 2021, 16:29
Is there any consistency to the max number of queued frames there are in OpenGL? I always assumed it was the same everywhere, but I get different results among different titles and even different PC's.
As I don't have a fast camera, I have to use more unreliable methods to measure frame latency. One way is to use something with hardware cursors and movable windows and measure the delta in a static photo. If that fails, a demanding title can be brought to a crawl until individual frames can be counted by hand. In my own simple application, the rendering is behind the cursor by five frames with Vsync engaged. If I add a glFinish(), it is reduced to one frame.
In Doom 2016, that number seemed to be only four, which could perhaps be a result of the sheer number of draw calls acting as a limiter for frame queueing.
However, on a different PC with a workstation GPU, the same simple application only lagged by four frames. Whether this is a difference in hardware, drivers, or something else is uncertain, but it suggests that there is a hard limit independent of render complexity that isn't universal.
What could explain this variation?
As I don't have a fast camera, I have to use more unreliable methods to measure frame latency. One way is to use something with hardware cursors and movable windows and measure the delta in a static photo. If that fails, a demanding title can be brought to a crawl until individual frames can be counted by hand. In my own simple application, the rendering is behind the cursor by five frames with Vsync engaged. If I add a glFinish(), it is reduced to one frame.
In Doom 2016, that number seemed to be only four, which could perhaps be a result of the sheer number of draw calls acting as a limiter for frame queueing.
However, on a different PC with a workstation GPU, the same simple application only lagged by four frames. Whether this is a difference in hardware, drivers, or something else is uncertain, but it suggests that there is a hard limit independent of render complexity that isn't universal.
What could explain this variation?