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[GhostDwemer]

Very interesting thread, and good science all around but it seems to me that no one has ever really verified the underlying hypothesis. Find a fort that is suffering from FPS problems and put it entirely back to starting conditions. Kill off excess dwarfs and animals, destroy excess items, block off every single path, then use dfhack's revflood to rehide the map.

Has anyone ever done that? If so, what happened?

[runlvlzero]

Reclaims don't suffer terribly, at least not for awhile, loading the reclaim may take long. But look at a fort like sword thunders, many people had quite playable FPS after reclaiming.

But its not the same as killing an active fort entirely with magma while saving a few dwarves to continue and test the cleaned fort, or save without relclaiming.

It would be a megaproject to design that experiment alone. Just a fort that's designed to die be renewed in 5 yrs time in game.

Not something I'm volunteering for...

But I recommend one big flat level fort thats easy to fill with magma, and obsidianize. Two Z levels tops. (not that the idea behind that is different then vaporizing or smashing stone)

Also some objects will survive, so the fort would need t be zero constructions and in some kind of melt able stone layer? no metals...

But what are the results have we established some curve graph with an outward life expectancy of a fort... like 25 yrs in game, without reclaiming? Does artificially removing items decrease that to say 10 years?

[NW_Kohaku]

Yeah, sorry for not updating this, I've been otherwise diverted...

I'll get around to the sock test sometime, I swear.

Anyway, I haven't found a definite source of permanent FPS decay in the system yet.  Granted, none of my experiments have gone beyond 10 years, but in those 10 years, I have had no notable gradual creep in memory consumption or decay in FPS.

This IS, however, with several controls -

First, nothing is dying except for a few rattlesnakes that get killed by the caravan guards a few years into the game.  We have not yet set up the puppy-smasher fortress that will test the effects of large-scale death on FPS. 

Second, there has yet to be a large-scale clothing rot test. 

Third, the fortress is not expanding in any way, and as such, no new dwarves are pathfinding, no new items are being (permanently) added, and there isn't more and more open space to pathfind over.

In order for a full and complete test, all other factors have to be gradually eliminated as we move in on the true source of gradual FPS decay, however, all current signs point to the notion that, basically, it's something done by the player that is causing all this permanent FPS loss.

If you were to very meticulously prevent any clothing rot or excavation or construction or warfare, you could run a fortress hypothetically forever...

... Of course, why would you WANT to run a fortress where you didn't build anything or kill anything, but that's a different story.

[runlvlzero]

Yeah, sorry for not updating this, I've been otherwise diverted...

I'll get around to the sock test sometime, I swear.

... Of course, why would you WANT to run a fortress where you didn't build anything or kill anything, but that's a different story.

Thanks for the update, I figured possibly as much since the OP was not edited with a summary. And of course even if we knew exactly what slowed forts down, we'd probably still do it cause it was fun =)

[NW_Kohaku]

Thanks for the update, I figured possibly as much since the OP was not edited with a summary. And of course even if we knew exactly what slowed forts down, we'd probably still do it cause it was fun =)

I can say this: Open space kills your FPS.  Pathfinding becomes geometrically less efficient (As in twice as much open space = four times longer to path) the more space there is in a fortress, so cram as much together as possible, and avoid those large rectangular open rooms.  Sprawl vertically, not horizontally when possible. 

Also, eliminate anything that you don't need from the game.  Magma-dump old socks, stones you aren't going to use, extra trade crap you can't sell, etc.  If your stockpiles overflow, don't dig out more stockpiles, dump and atomsmash your excess.

You can "undig" some parts of your fortress using DFHack.  I haven't done it, but I'm told that if you seal off and unreveal parts of your fortress, you can get some FPS back from the game.

[expwnent]

Pathable open space or any open space? Does above ground air count?

I'm planning a megaproject and I'd like to not die of FPS boredom.

[RadHazard]

How much do well-placed traffic designations help alleviate the open space issue? That could be another thing to test when you get around to the open-space testing.

It would be interesting to see if designating traffic zones like below would improve FPS noticeably, with larger rooms, of course.

Code: [Select]

F = Forbidden
H = High Traffic
╔══┼══╗
║FFHFF║
║FFHFF║
┼HHHHH┼
║FFHFF║
║FFHFF║
╚══┼══╝


[NW_Kohaku]

Right, I've done some testing on open space. All testing was done with modded (nosleep/drink/eat, speed 0) dwarves digging out areas of white sand, in full screen, with as little as possible running in the background.

Spoiler: Kohaku spoiled to get to the good bits (click to show/hide)

Results:

initial FPS: 2000
FPS whilst digging out a small area (600 ish tiles): 50
FPS after digging out said small area: 1500
FPS whilst digging out a larger area (maybe 1500 tiles or so): 5
FPS after digging out said larger area: 1500
NOTE: at this point, several things happened:
1) First hardcoded migrant wave arrived and a ghost appeared
2) I finally remembered to turn weather etc. off
FPS after above changes: 2600
FPS whilst digging out another small area: 3
FPS after digging out said small area: 2300 (NOTE: unreliable, as I was only able to observe for a short time due to another migrant wave and a caravan arriving. After the caravan left, FPS was down at 2100)
FPS whilst digging out 7 tiles: 5
FPS whilst digging out another small area: 20
FPS after digging out said small area: 2100
FPS with an entire inaccessible z level designated: 1950
FPS after undesignating said inaccessible z level: 2050
NOTE: At this point, two migrant waves arrived, half the fortress got married, a child was born the elven caravan arrived and two ghosts appeared.
FPS after above note: 1000
NOTE: the above changed by +/- 100 points with seasonal variations, away from autosaves
FPS whilst digging out another large area: 2
FPS after digging out said large area: 900
FPS after digging out another small area and a really annoying migrant wave: 730
FPS after digging out another small area, a really annoying dwarven caravan (still present) and three really annoying births: 600
FPS after caravan left and digging out another small area: 600
FPS after digging out another small area: 600

At this point, I decided to test whether open space and floored space had the same effects, so I started channelling out all of the areas I'd previously dug out.

FPS after collapsing first area (two deaths, one birth, one lightly mangled baby, two lightly injured miners): 420
FPS after collapsing second area (one light injury, one birth): 380
FPS after collapsing ridiculously massvie area: 300
FPS after digging out another small area: 280
FPS after channelling that area out the slow way:230

Conclusions:
Empty space slows stuff up.
The accessibility of space has no noticeable effect.
Channelled out space is actually worse than floored over space.
Designating things does slow stuff down, but nothing like as much as actually having them accessible.
Weather etc. has a significant impact on FPS.
There are significant seasonal variations in FPS.
Caravans still slow things up after leaving the map.

[Khym Chanur]

You can "undig" some parts of your fortress using DFHack.  I haven't done it, but I'm told that if you seal off and unreveal parts of your fortress, you can get some FPS back from the game.

So revealing (and exploring) the caverns will cause a permanent FPS drop?

[NW_Kohaku]

It's not the revealing, it's the connection.  The larger the open space, the more it hurts FPS.  Caverns have large amounts of open space, and they hurt your FPS even before you reveal them.  What happens when you completely seal off a region, though, is that you can semi-permanently prevent them from interfering with pathfinding.

The open sky is bad for FPS, as well.  Making less sky above ground level in worldgen makes the game run faster.

[GavJ]

... Of course, why would you WANT to run a fortress where you didn't build anything or kill anything, but that's a different story.

Well, of course you wouldnt want to play a fort doing NONE of those things.  But it may well turn out that only ONE thing in particular seems to murder FPS in more normal gameplay.  For instance, it's always pretty much the kill list, or something.

If that's the case, then it would still be very useful to know, because we could play very fun fortresses for a long time, doing all the fun stuff, but simply avoiding too much of that one fun thing.  Not to mention the likelihood of toady fixing it being higher if it can be pinpointed (i.e. the whole point of the thread).

Posting to make the above inane comments and to follow.

[GavJ]

I have the pleasure to announce the results of my mass bunny smashing experiment.

Start of the fortress = 1700 FPS
2 waves of migrants + wild animals roaming + a couple caravans come and gone + about 30 baby bunnies = 950 FPS
Same as above + 22,500 bunnies = 0.2 FPS
Same as above minus 22,500 bunnies smashed = 150FPS
Same as above + all the rest of the bunnies + all but 7 dwarves smashed = 225 FPS

Time it takes to save the game now = about 1 minutes (interestingly it stalls on "cleaning game objects").



So 22,500 corpses listed in the missing page seems to reduce my FPS by a factor of 4.  Not really as bad as expected.

[runlvlzero]

I have the pleasure to announce the results of my mass bunny smashing experiment.

Start of the fortress = 1700 FPS
2 waves of migrants + wild animals roaming + a couple caravans come and gone + about 30 baby bunnies = 950 FPS
Same as above + 22,500 bunnies = 0.2 FPS
Same as above minus 22,500 bunnies smashed = 150FPS
Same as above + all the rest of the bunnies + all but 7 dwarves smashed = 225 FPS

Time it takes to save the game now = about 1 minutes (interestingly it stalls on "cleaning game objects").



So 22,500 corpses listed in the missing page seems to reduce my FPS by a factor of 4.  Not really as bad as expected.

Haha, thanks for the test run, that gives a little perspective. The way I play I would imagine reaching 22,500 missing and dead might take a few minutes 

[MarcAFK]

Is that final result after saving Quitting, and reloading?

[GavJ]

Is that final result after saving Quitting, and reloading?

yup