NetworkPerformanceSystem

NetworkPerformanceSystem

Network Performance Systems is a general networking overhaul, designed to tackle the problem created by high ping.

In Valheim, most objects are simulated by users. So a single high ping user in an area can make everything or all sorts of things feel terrible.

This mod aims to address that in a number of ways.

Why this is different from the other networking mods

Every other Valheim networking mod treats multiplayer performance as a bandwidth problem —

compression, bigger buffers, higher send rates, filtered broadcasts. That is the right diagnosis for

ten people in one base saturating a shared cap. It does not handle a larger distributed server, or multiple players from

vastly different goegraphic locations.

NPS addresses these issues in a number of ways

• Each peer gets their own Round Trip timing (RTT), Healthcheck and bandwidth estimates
• This allows dynamic adjustments to route around a poor connection
• This higher ping players with decent bandwidth allow the server to send more aggressively to these players in compensation
• Object ownership can be dynamically adjusted around players with poor connections to provide the best experience for all players in the area
• Objects which need network calls to interact with get ownership transferred ahead of time, delay scenarios much less likely
• Objects that change ownership during active requests get their requests properly re-targeted against the new owner, and an item that still cannot be delivered is dropped at the station instead of lost
• Objects which are locally important (footsteps for example) are only network broadcast locally, instead of globally around the server
• Server Garbage collection churn is significantly reduced compared to vanilla

Installing

Server-only works. Vanilla clients get the send window, ownership, scheduler, station-request and creature-hit

fixes with nothing installed on their end, and the server follows where they actually are rather than where they

were two seconds ago. The server also sends settled or distant creatures, and fish and birds, to each player less often,

holds back building, tree and rock updates that change nothing a player can see, and sends the world's list of past

players only when it has actually changed. Damage numbers go only to players close enough to see them, and

Routed RPC / Damage Numbers can limit them to the player who landed the hit, or stop sending them at all.

Installing on clients too adds latency compensation, live position reporting and the clean exit

from a dead session for those clients, and lets a ship they own pass to whoever takes its helm.

Creatures they simulate stop re-sending themselves while standing still, which matters most next

to a pen of tamed animals, and fish and birds they simulate are sent a few times a second instead of

every frame, which matters most by water. Their game also tells the server how smoothly it is

running, so a player whose machine slows down in a big fight is given fewer creatures to run.

Mixed groups are fine — benefits are per-player, and a client without the mod behaves

exactly as vanilla. There is no version lock: nobody gets kicked for not having it.

Works on dedicated servers and on player-hosted games.

Diagnosing and Reporting a problem

An easy way to start is enabling the nps_stats display Run nps_stats_collect (needs devcommands, since sampling costs a Steam call per peer per tick), play, then nps_stats.

A player the link-pressure table marks as LOSSY is already being dealt with: the server steps that one player's send rate down until their connection stops losing packets, and back up once it is clean, without changing anyone else's rate (Steam Transport / Enable Loss Backoff). A player whose loss does not improve - once their rate is below what their connection was already carrying, or at the lowest rate - has a connection problem the rate cannot fix: they go back to full speed and are left there until the server restarts. Loss