Internal fixed frame rate (25fps)

[WolfS]

Hey community!

I have still a lot of problems with KSP, beside it makes a lot of fun.

Here is the actual problem:

After building some smaller rockets I tried to do something bigger (300+ parts).

The building was not the problem, the problem started at the launch pad. The rocked exploded because of the gravity impact and the game was not play able. So I opened with "alt + F12" the performance tool. And I had "fix" 25 fps.

What to I mean with "fix" 25 fps? Well, if you do a normal performance check you will have some up- and down spikes. But this line was laser-light-beam-straight. No "ups" nor "downs".

The first step: Blame the others! Due to the fact that I was using some part mods I thought that maybe one mod was destroying my gaming performance like China was destroying all hope for Tibet. So I decided to open a big ship with just stock parts. The mighty "Starhammer" from ShadoZone (557 parts).

No changes at the launch pad. I still had fixed 25 fps.

Second step: Just...just blame still the others". Because I was also using some graphic mods I decided to installed a clean KSP v1.0.2 with no mods. That version was that fresh like the with snow in the never-ending wildness of Siberia during a long and cold winter.

No changes at the launch pad. I still had fixed 25 fps.

Third step: Increase the power...huahuahua! So I downloaded "Nvidia Inspector" (for sure the actual version 1.9.7.3) to optimize my settings. I played around with the Nvidia-settings like an 14 year old boy do it with boobs during his first .... time.

No changes at the launch pad. I still had fixed 25 fps.

Forth step: I got "a little angry"...not so angry like the people during the French Revolution but sill a bit. And so I decided to clean install Windows 8.1...why not. We do all for the game, right? ^^

No changes at the launch pad. I still had fixed 25 fps.

Fifth step: The duel - part 1: Maybe the reason was the version of KSP. So installed a also very clean version of KSP v0.9 and loaded the "Starhammer".

No changes at the launch pad. I still had fixed 25 fps.

Sixed step: The duel - part 2: I used the maximal graphic settings in KSP v1.0.2 and recorded the frame rates. Than I used the minimal graphic settings to compare those both. And the result was very interesting:

The test environment: The Base-Screen. The VAB-Screen. The launch pad-screen:

Minimal Settings: about 60 fps. about 60 fps. fixed 25 fps.

Maximal Setting: about 60 fps. about 46 fps. fixed 25 fps.

And my GPU was not even used to 100% from the game. Around 50° C.

I mean, the GPU was that bored he counted to infinity and back because he was bored to tears. Not even the fans were turning on. So maybe there is some space for optimizing the resources.

And neither was the CPU on his limit. He just "warmed up". Around 50°C.

If I play "War Thunder", which is raping my GPU, I have 85° C and more (with 70 fps) and the fans are spinning around like some cool rappers in a underground club.

But still, even with the lowest possible graphic setting: I still had fixed 25 fps.

Seventh step: Maybe ask the others^^ So in the forum I learned a lot about KSP. It just use one core and not all of my 16 GB of ram. But....but this all makes still no sense because of the "fixed" frame rate of 25 fps.

Imprortant information: If I load the pre-installed aircraft "Stearwing A300" (105 parts) and launch it at the launch pad I have, with maximal graphic settings, a frame rate of around 60.

So my question to the community is: Do you also have noticed this strange "fixed 25 fps" when you start an 300+ part ship? Maybe some of you will donwnload the "Starhammer" and tell me your frame rate at the launch pad.

My Computer:

GPU: Geforce GTX 880m

CPU: i7-4700HQ, 3,2 GHz

Or, do you know some work arounds for getting off this "internal fixed frame rate"?

Best regards

Edited June 9, 2015 by WolfS

[includao]

Any solutions?

[Padishar]

That frame rate indicator is not accurate at <= 25 fps. That is basically the minimum value it will ever show. Try using a different way to display the actual fps you are getting (either install one of the mods that tells you it or use something like fraps to show it).

The primary limiting factor on framerate with large ships in KSP is the physics calculations. These only use a single core of the cpu. The amount of calculations required is basically proportional to the square of the number of parts so if you double the number of parts then four times the calculations are done.

[cantab]

That frame rate indicator is not accurate at <= 25 fps. That is basically the minimum value it will ever show. Try using a different way to display the actual fps you are getting (either install one of the mods that tells you it or use something like fraps to show it).

Really? That's a splendid blunder.

It reminds me of something that happened when the Antarctic "ozone hole" was first being investigated. Measurements from the ground were showing very low amounts of ozone in the ozone layer but satellite measurements were showing normal levels. It turned out the computers processing the satellite data had been programmed to assume low values were errors and throw them out, producing a similar result to our fps readings here.

[Padishar]

I believe it is actually showing the number of physics frames per in-game second. While your actual frame rate is above the max physics delta time value (defaults to 0.04 for 25 fps) then the value is the same but once time starts getting stretched (because each frame takes longer than 0.04 of a second) you get stuck with the value of 25.

It can be shown very easily. Just load a reasonable sized vessel (e.g. Kerbal X) and add a spot light to it and then change the light colour to (0.45, 0.65, 0.9) and leave the tweakable open. This will trigger a bug that will cripple the framerate. It will be obviously below 25 fps but the debug window display will still say 25...

Edit: note, the bug will also cause KSP to leak memory rapidly while the tweakable is open so don't leave it open too long (especially if your install is mod heavy and uses lots of memory) or KSP will crash...

Edited July 5, 2015 by Padishar

[includao]

I believe it is actually showing the number of physics frames per in-game second. While your actual frame rate is above the max physics delta time value (defaults to 0.04 for 25 fps) then the value is the same but once time starts getting stretched (because each frame takes longer than 0.04 of a second) you get stuck with the value of 25.

It can be shown very easily. Just load a reasonable sized vessel (e.g. Kerbal X) and add a spot light to it and then change the light colour to (0.45, 0.65, 0.9) and leave the tweakable open. This will trigger a bug that will cripple the framerate. It will be obviously below 25 fps but the debug window display will still say 25...

Edit: note, the bug will also cause KSP to leak memory rapidly while the tweakable is open so don't leave it open too long (especially if your install is mod heavy and uses lots of memory) or KSP will crash...

So once my i7 4930k @ 4.6ghz with a GTX 980 can't produce (physics calculations + complete rendered graphics) in less than 0.04, it forces the total FPS to be 25fps, so that KSP can actually prioritize proper physics calculation in a reasonable timeframe, correct? It sounds reasonable to me. However, I wish Unity could use more processing power in the physics calculations.

[Padishar]

No, once the time needed to do the calculations exceeds 0.04s it uses 0.04 seconds as the physics timestep instead of the actual time between the rendered frames. This has the effect of slowing down the in-game clock (the timer goes yellow, or red if it gets really bad). E.g. if it takes 0.1 seconds to do the calculations then you will get 10 frames rendered per second but the in-game clock will only advance 10*0.04 = 0.4 seconds in that 1 real second.

The Unity 5 update coming in KSP 1.1 should improve matters (though how much is still speculation). There are also lots of other areas of the game that can be optimised to improve the performance with large vessels.

[includao]

No, once the time needed to do the calculations exceeds 0.04s it uses 0.04 seconds as the physics timestep instead of the actual time between the rendered frames. This has the effect of slowing down the in-game clock (the timer goes yellow, or red if it gets really bad). E.g. if it takes 0.1 seconds to do the calculations then you will get 10 frames rendered per second but the in-game clock will only advance 10*0.04 = 0.4 seconds in that 1 real second.

The Unity 5 update coming in KSP 1.1 should improve matters (though how much is still speculation). There are also lots of other areas of the game that can be optimised to improve the performance with large vessels.

Thanks for explaining it to me. It all makes sense now <3