Which One Is Frame Rate

[mojoseeker]

I have a line of data in my upper leftscreen area. It shows F-act, F-sim and Frame. The data under the three shows 15.0, 19.90 and 0.067.

What do the numbers mean and which should I be concern with (frame rate)? Thanks

[chris k]

First one is the actual frame rate you want to read (f-act) - it's the FPS being achieved on your video card.

Second one (f-sim) is the math internally that X-Plane is trying to use for it's physics calculations. It should never drop below 19 or so, else things become unpredictable. If your f-act is below the f-sim value, then it's running in slow-motion since the video card cant keep up.

The third value "frame time" is the elapsed time in milliseconds between finishing the calculations and pushing info to the video card, and the return from the video card. (I believe - someone correct me if Im wrong here..) i.e. how long it's taking OpenGL to render the frame... as this is outside X-Plane's control once it instructs the card what to do. For example, if my video card (f-act) is doing 50 FPS = 1000ms / 50 frames = 0.020 sec per frame, which is about what I see on my system.

- CK.

[s839sd82k]

How do you show frame rate?

[PhM]

... If your f-act is below the f-sim value, then it's running in slow-motion since the video card cant keep up....

In fact the rendering frame time depends on many parts of a system, to make it simple if you get slo-mo then :

- If your GPU usage is at, or close to, 100% you are GPU bound, it can't keep up with what has to be done.

- If your CPUs usage is at, or close to, 100% you are CPU bound they can't keep up with what has to be done.

- If none of the above applies then your are API (openGL) or I/O (PCIe) bound.

PhM

[MdMax]

How do you show frame rate?

In Data Input & Output, then select frame rate:

http://wiki.x-plane.com/Chapter_5:_X-Plane_Menus#The_Settings_Menu

[FloB]

In fact the rendering frame time depends on many parts of a system, to make it simple if you get slo-mo then :

- If your GPU usage is at, or close to, 100% you are GPU bound, it can't keep up with what has to be done.

- If your CPUs usage is at, or close to, 100% you are CPU bound they can't keep up with what has to be done.

- If none of the above applies then your are API (openGL) or I/O (PCIe) bound.

PhM

Can you explain what API-bound means?

In fact neither my CPU (i7 2600k@4.2) nor my GPU (GTX670@stock, 2GB) is close to beeing maxed out.

CPU-load is typically 75% at one core, others are used to around 40% (windows task manager, performance monitor).

GPU-load is around 70%. NVIDIA Inspector shows that the "bus-usage" is almost zero (but maybe this is not the PCIe bus?).

Framerates are good and about what I expected - but it's weird nonetheless. Only way to max out the GPU is running HDR+SSAA.

Just curious how that makes sense...

Thanks

Flo

PS: XPlane's FPS counter always shows a CPU usage of 0.998 or so.

Edited July 31, 2012 by FloB