Swarm CPU/Core/Thread Limit

Dear Epic, dear Community,

I wanted to ask if there is a Limit on the amount of CPUs/Cores that Swarm can use?
To be more precise:
(1) is there a limit on swarm agent clients?
(2) Did anyone try a dual socket machine and does swarm use both processors without problems? If so, does it scale well?
(3) For example using the latest and biggest 18 Core Xeon, this would result in 72 Threads (Dual CPU) on Windows on a single machine. Could the Swarm Agent take use of all the threads or is there a limit? Any experiences?

Thank you for all the input in Advance;


Hi there,

There does not seem to be a limit on the number of cores/threads for Swarm, I have seen a few posts where they were using 72 or higher number of threads. Epic uses a network of servers that could potentially have 5-10x (possible more) more than a dual 18 core Xeon setup.

Here is a quote from the release notes of UE3 2009-11 Beta explaining how it works:

Unreal Swarm is a massively scalable job distribution system optimized for high-speed networks of multi-core PCs. Designed in tandem with Unreal Lightmass to accelerate lighting computations, Swarm can manage clusters of computers of mixed brands, configurations, and performance levels, automatically distributing tasks on-demand and employing a transparent distributed cache system that allows for dramatically increased performance.

The only documentation currently available for swarm can be found here:


So whether you are building a server farm, or a single high powered server, you will be able to make use of all those cores. :slight_smile:

So I guess (1) can be answered No, there thus not seem to be a reachable^^ number of swarm agent clients. But what about 1 machine with high core count? Anyway, thanks for your answer! :slight_smile: I will wait for any more feedback before upvoting your answer, if this is ok with you :slight_smile:

Hey, I just solved the problem.

  1. In Swarm Agent, go under the “Settings” tab, set “EnableDeveloperMenu” to “True”. Now DeveloperSettings tab appears.

  2. Under “Local PerformanceSettings”, there’s a “LocalJobsDefaultProcessorCount”. Set that to the number you want.

3.Restart the Swarm Agent and enjoy your newly unlocked power.