Processor Greed

Unity Engine
1

We’ve been getting some feedback from users playing our game that their systems’ processors spike to 100% while running the game. It then stays up there even when the app is hidden. It’s causing powerbooks to run rather hot.

Is this a usual occurance with Unity-built projects (I never really noticed it on my machine, but I’m running a G5)? And is there anything I can do to make the app less processor hungry?

If it helps, there’s a build of it available at:

http://redrovergames.com/scramble/scrambledMAC.zip

Thanks,
-rob

2

In trying to get as high framerates as opossible, 3D engines will generally use all the processor power they can get.

First: by default Unity pauses in the background. To make sure it does, uncheck “Run in background” in the player settings ( http://unity3d.com/Documentation/Components/class-PlayerSettings.html )

Second: in the case when you want fewer frames per second, someone came up with a method to sleep a few milliseconds during each frame, to force Unity not to go above some number of frames per second. Jonathan Czeck just told me that you should do this:

import System.Threading;
Thread.Sleep(milliseconds);

The trick is to calculate how many milliseconds so as to limit the framerate only if it’s “too high”.

d.

3

This quick script seems to work okay, but the calculation could probably be made a lot better. :slight_smile:

import System.Threading;

var goalFPS = 30;
	
private var millisecondsToWait = 0;
	
function Update ()
{
	var overflow = 1.0/goalFPS - Time.deltaTime;
	if (overflow > 0.0)
		millisecondsToWait ++;
	else
		millisecondsToWait --;
	
	Thread.Sleep(Mathf.Clamp(millisecondsToWait, 0.0, 1.0/goalFPS * 1000.0)); // clamp for sanity		
}

-Jon

4

Thanks for the input.

We have our game set to run in the background in order to prevent cheating (it’s a timer-based word game). However, I believe that there’s a way to access the runinbackground variable from the script so at least I can turn it to false while in menus or paused.

I’m going to try the script Jonathan provided and see if that affects anything.

Thanks again,
-Rob

5

Well, that worked beautifully. We were able to relinquish about 80% of the processor load by capping Unity at around 60 fps.

Thanks guys!

-rob

6

That’s great to know! It seems especially appropriate for Scrambled type games.

-Jon

7

Seems like a good script for the wiki.

8

Oh, and dynamically setting the runInBackground toggle worked nicely, too. During any time where the timer is inactive (menu screens, paused, or non-timed game modes) we have the app turn off runInBackground which makes our app use a measly 2-5% processor on our test MacBook Pro.

Ahhhh, I love a productive day : )

-rob

9

Stupid question maybe, but where should Jonathan’s script be put?
Should it be attached to just an object in the Hierarchy?

10

Yes. Attach to any game object.