Let me guess: BtS is not multithreaded, right?

[Underseer]

You know, with a game that sucks down CPU cycles like this one, it seems a crying shame that it can't take advantage of multi-core processors.

[Kuciwalker]

Multithreaded AI is hard.

[Underseer]

Then put the AI all in one thread.

[Blake]

It happens that CIV benefits significantly from dual core CPU's, despite not being designed to. Possibly some of the core engine is multithreaded or something.

I can say that when I upgraded from a AMD 64 3800+ (2.4ghz) to an AMD X2 5600+ (2.8ghz, dual core), the in between turn times were cut to about 1/5, which was a far more significant increase than would be expected for a strictly single-threaded application (I also got faster ram so it's not a fair test but some of that huge performance gain simply must be attributed to the second core).

[Wiglaf]

Whatever, the game runs fine on my piss of the line laptop from 2 years ago.

[Underseer]

Originally posted by Blake
It happens that CIV benefits significantly from dual core CPU's, despite not being designed to. Possibly some of the core engine is multithreaded or something.

I can say that when I upgraded from a AMD 64 3800+ (2.4ghz) to an AMD X2 5600+ (2.8ghz, dual core), the in between turn times were cut to about 1/5, which was a far more significant increase than would be expected for a strictly single-threaded application (I also got faster ram so it's not a fair test but some of that huge performance gain simply must be attributed to the second core).

Upgrading from a dual core to a faster dual core CPU is probably not a good example for what you are trying to demonstrate, but yeah, I know what you're saying. I made a jump from a single core AMD chip to a dual core AMD chip. Both had very similar technology and the dual core had only a slightly higher clock, and I was pleasantly surprised at the result.

Yes, the game runs fine for me 99% of the time, but there are circumstances (particularly late game on huge maps) when it does slow down a bit.

[Blake]

The AMD 64 is not a dual core cpu.

[Underseer]

Ah, gotcha. I misread that.

Still, it's a huge difference in technology, so one core of your new CPU is significantly faster than the CPU you had. For me it was a slight bump in clock speed, but otherwise the major difference was the addition of another core.

Eh, sorry for getting sidetracked.

While I did notice a greater performance improvement than expected, I believe the game is not multi-threaded. That point has been mentioned to me plenty of times here and at the other major Civilization fan site, so this information must come from the developers (interview, maybe?). I think the performance bump I noticed was from all the other processes getting moved to the other core, leaving Civ4 with a core to itself.

[Kuciwalker]

Originally posted by Underseer
Then put the AI all in one thread.

The AI is most of the computation.

[Kuciwalker]

Really, consider how the engine works. There are the graphics, which are mostly determined by the graphics card. The rest of the game is played as a sequence of actions. In SP at least, you simply cannot do two things at once. And the rest of it - the turn time - is AI.

[LDiCesare]

Galciv is multithreaded, mostly for the ai, so Civ IV could be too. Except if the core game was not, I can't see how or why they'd rewrite everything to be multithreaded for an xp. Too much work for almost no gain for most players.
And there's always a graphics thread and a game thread, and not everything graphic's running on the graphics card.

[Dale]

Originally posted by Blake
The AMD 64 is not a dual core cpu.

I got a AMD Atholon 64 X2 which is dual core.

But on topic, I noticed a MASSIVE increase in performance going from P4-2.4 to the above CPU.

[Blake]

I believe that in CIV the graphics actually run in a separate thread(s) to the game/AI code. The graphics continues to be updated during the AI turns...

[Kuciwalker]

Originally posted by LDiCesare
Galciv is multithreaded, mostly for the ai, so Civ IV could be too.

Galciv did some kind of wizardry where the AI ran in a separate thread during the player turn. I assume it just helped the AI compute an approximation of what it would (since it obviously couldn't respond to actions the human hadn't made yet). The AI itself wasn't multithreaded.

[ben04]

Well there are things an AI can do while waiting. For example a better but more expensive algorithm to choose where to found cities or planing what workers will do. It is rare, that a player can change the game so dramatically in one turn that that information would become too much outdated to be useful to the AI. It is however a potential exploit as the AI basically is a turn behind the player when it comes to certain stuff.