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
How many cores do you have???
I have 8 physical cores, 16 logical cores.
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.
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>
That is odd, my XML is empty and I run 2 threads per core automatically.
when I use UE4, it’s 2 threads per core, but UE5 default use 1 thread
Why did Epic Games lock the number of threads per physical core? There must have been a good reason for that, considering that 2 years have passed and 5.4 still defaults to 8 threads instead of 16. Will everything work stably if I use the configuration provided by JeferWang?