[2.0.15] MP performance issue : Poor cnx quality (wifi) + turret AI

[Malak044]

Hi all,

So yesterday, our savefile tiped us over the sweet 60 FPS performance. We struggled to figure out & pinpoint the culprit.
Overview of the setup :
Server running in linux headless (docker) on a dedicated server baremetal (not some paid/month subscription at a datacenter). The server specs are just a beast. The factorio running was never using more than 100% CPU (so 1 core), barely going over the 100% from times to times (depending on the "action" on the map).

2 players with similar setups :

1. AMD Ryzen 7 5800X 4GHZ (pretty good CPU)
2. RTX 4070 12GB
3. 32 GB RAM DDR5
4. 1 player is playing from "localhost" (still had a to do a loopback from public IP)
   • godly ISP cnx (2.5 Gbit/s UP/DOWN).
5. 1 player is playing from 400Km apart
   • problematic ISP cnx (1GBit/s WAN, but LAN setup with CPL only reaching max 30MBit/s, with potential packet loss).

Context :
Running Factorio Space Age default mapgen, went a bit deep in our remodeling of the Nauvis base (went 30ish kms east, up to when ore patches hit approx 150M/patch). The full east path is a turret heavy border guarded dual train lane (approx 12k laser turrets). With limited bug control (only so that they dont aggro non stop the border, but no artillery).

Problem :
For the problematic player, the save is running smooth 60FPS (with update tick approx 15) on singleplayer, but running with 4fps most of the time in MP.

After a talk with some community member (https://discord.com/channels/1396775903 ... 4958526534 <- discord topic). We decided to start fixing main potential problems :

• Fulgora sorting station was full, approx 2k bots in the air with items they cannot drop (have to wait a backed up inserter logisitic "junk chest").
• Bugs might be too close to some turrets, even tho they arent aggressive and not engaged in combat (turret in idle state, apparently the AI behind the turrets still target calc bugs up to some default legendary range). We decided to slowly add artillery around our borders.

The main issue pinpoined was the "turret time" being over 4 out of the 16-17 time per tick (which might be scewed, since apparently the target acquisition might not be represented in that number).

Solution :

• First fixed the fulgora sorting station, gained approx 1fps out the 60, basically doing nothing
• Then added artillery around the "main base" (nothing around the 30km trench going East), tipped us back on track.

This basically removed nests around pollution area & cleared our border mainly composed of flamethrower & small amount of laser. The trench still has 12k laser turrets (will continue clearing up, but takes time).

We believe there is something in the Flamethrower (or any turret) AI that makes it particulary bad in calc (over MP ?)


LogFile :

factorio-previous.log

log file

(64.96 KiB) Downloaded 4 times

Mods : vanilla spaceage, default mapgen
Screenshots :
Debug options

11 fps

turret-ai-fps-1.png (6.72 MiB) Viewed 172 times

Partial Layout of nauvis (cannot fit in one screenshot)

the trench.png (326.05 KiB) Viewed 172 times

Active Chunks around trench (sadly no screenshot around the flamethrowers)

active chunks.png (209.14 KiB) Viewed 172 times

Frames back to 60FPS

frames-back.png (1.23 MiB) Viewed 172 times

Layout of the mainbase defense border

layout-defense.png (1.8 MiB) Viewed 172 times

Save files : (approx 100MB)
- With 5FPS : https://drive.google.com/file/d/1oqPAPY ... drive_link
- With partial fix solution (gave us FPS back) : https://drive.google.com/file/d/1oKAYMn ... drive_link

[Malak044]

After clearing up everything, we ended up with turret being 0.005/tick

fixed.png (1.1 MiB) Viewed 114 times

[Rseding91]

Thanks for the report however I don't see any bug here. Turrets use the exact same code in single player and multiplayer (in fact, all entities do). They have always been a higher tick-time using entity because they have to scan for things to shoot when there are things nearby to shoot.

[Malak044]

Well the problem was that on version 1.X, I really didnt struggle. I can understand that the code behind turret didnt change. But maybe the update 2.X highlighted something since now the range for calculation is higher than the actual range of the turret (maybe this is wrong, this is some assumption).

In the end, a playstyle that was working fine in MP in 1.X is now struggling in 2.X (about turrets whereabouts not being cleared by artillery).

The most "disturbing part" is the fact that for the save in 2.X, I can play fine in Solo, but in MP, I'm "gated" by the cnx or something like that. I see the MP buffer spiking some of the time. Mostly unplayable.

Finally, I've personnally learnt how to avoid the situation. After 20+h of artillery placement, we went back to 0ms/tick on turret. So We gained back those 8ms/tick. And I know that this is an area to watch about. Maybe there is nothing wrong like you said, you definitely are more an expert than me. I was thinking maybe there are alot of unecessary packets for turret synchronisation in MP that "clutter" the cnx.

Anyway, thx for the update, it's amazing so far <3 ( except this "issue" that required us to do a big workaround )