Topic: widelands and CPU usage

I've been checking the use of my laptop's resources to see if I could identify the cause of some slowness, and I've been fairly surprised by what I saw in widelands. I was playing a 300x300 map (no metal challenge, that i posted yesterday) with a game that had lasted 13 hours, and i noticed that widelands took over 30% of my CPU. That's understandable, big map, long game. But I went to do otjher stuff, and I paused the game, but it still consumed 30% of the CPU. I can understand that all the calculation for tree growth and road traffic and ware destinations would take a lot of processing, but when the game is paused? For the sake of experiment, I raised the speed to 10x, and the CPU usage increased to 35%. Not much. So, all those factors I mentioned before only make for a very small amount of the total CPU usage.

I was intrigued and tried some different stuff then. I opened the smallest map, crater, and the consumption is 15% now. I suspected it could have something to do with terrain animations, but crater has an area 20 times smaller than no metal challenge, so it can't be that either.

Last, I tried to open a new game in no metal challenge. The CPU usage this time was 15% or less. So, a new game takes less resources than an old one. But why is that?

There are two options. One, all the buildings are taking CPU. Two, CPU usage increases with time. Luckily, I found an old save on the same map where the game had lasted 4 and a half hours (but most buildings had already been completed), and I opened that, and the CPU usage stabilized around 20%. Bingo. An increase of 5% of my CPU every 4 hours, starting with 15%, would fit very well with 30% after 13 hours.

I already remarked long ago how long games tend to slow down as they take more and more of a pc's resources: https://wl.widelands.org/forum/topic/1589/ Ironically, I was in a no metal challenge also that time, because it's the only way to make games so long that they last tens of hours.

Anyway, I think there must be something wrong with the coding. If nothing else, there must be some room for optimization. It's not possible that the vast majority of CPU consumption of the game comes from passing time independently from what you actually do in the game. Or that the game keeps eating resources even when paused.

P.S. It wasn't widelands that slowed down my pc anyway; problem was reading from hard disk, and it was windows shit doing that.

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seems pretty strange that statistics would require CPU. the way I see it, they should be a string of data, minute per minute, so they should occupy memory, but they should not require particular calculus.

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I guess the question about the statistics here is how much of it is calculated on the fly, and how much of it is stored. I am not familiar with that part of the code. Also, plotting graphs takes more CPU than displaying text.

I think improving the performance is generally a good idea, but I personally don't have any practical experience whatsoever with profiling etc.

Busy indexing nil values

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king_of_nowhere wrote:

by the way, i checked, and opening the statistics only increase CPU usage by a few %.

I remember that the major problem was with statistics for "full game". Calculations are pretty easy, but they probably were done every frame. That can be very RAM-usage. I guess that now it is better than before, but you can check whether displaying full game statistics are making difference?

But I am not saying that only statistics make CPU-usage! I remember that in the past it was bottleneck for the game. There is number of places where bottlenecks can be. (computer AI for example)

einstein13
calculations & maps packages: http://wuatek.no-ip.org/~rak/widelands/
backup website files: http://kartezjusz.ddns.net/upload/widelands/

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If you want to check on the CPU usage all the time, why don’t you play windowed? Just to test it.

Two is the oddest prime.

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