How to use all cpu core when UE5 make installed build from source?

Development Platform & Builds
, , ,
1

when I try to build UE5 from source, the RunUAT.bat script only can use half of cpu core.
I try to modify BuildConfiguration.xml in my user folder, but its no effect.
I have 8 physis cpu cores, 16 logical cores.
How to use all cpu core when make installed build?

./Engine/Build/BatchFiles/RunUAT.bat BuildGraph -target="Make Installed Build Win64" -script="Engine/Build/InstalledEngineBuild.xml" -set:HostPlatformOnly=true -set:WithDDC=false

image
image2280×1022 202 KB

image
image1076×486 15.3 KB

2 Likes
2

How many cores do you have???

4

I have 8 physical cores, 16 logical cores.

5

It looks like it’s limiting it to the amount of physical cores. Logical cores is just the number of physical cores times the amount of hyper-threads it can run. I don’t think you would see double the performance if it could utilize them as the threads share CPU cycles. There is probably some good reason why it sticks to physical cores.

6

I found a solution, for my 8 core 16 thread cpu, now I can use 16 thread compile my ue5 project. modify BuildConfiguration.xml at this path: C:\Users\xxx\AppData\Roaming\Unreal Engine\UnrealBuildTool\BuildConfiguration.xml, add ProcessorCountMultiplier tell unreal use two thread one core. my config file like this:

<?xml version="1.0" encoding="utf-8" ?>
<Configuration xmlns="https://www.unrealengine.com/BuildConfiguration">
        <BuildConfiguration>
                <MaxParallelActions>16</MaxParallelActions>
        </BuildConfiguration>
        <ParallelExecutor>
                <MaxProcessorCount>16</MaxProcessorCount>
                <ProcessorCountMultiplier>2</ProcessorCountMultiplier>
        </ParallelExecutor>
</Configuration>
4 Likes
7

That is odd, my XML is empty and I run 2 threads per core automatically.

9

when I use UE4, it’s 2 threads per core, but UE5 default use 1 thread

1 Like