Hi @michaelmonte ,
In Luoshuang’s GPULightmass not affected
In ue5-main (5.4) the main change in Epic GPU Lightmass announced are in Path tracer for DXR raytracing for color.
The quote from change commit is below
Path Tracing: Refactor how shadows are traced
Go back to using Any-hit shaders (AHS) instead of Closest Hit Shaders(CHS) for colored shadows in the path tracer. To avoid artifacts from the Bounding Volume Hierarchy(BVH) reporting multiple hits against the same primitive, simply use the payload to check if the previous hit is at exactly the same distance.
This assumes that redundant shader invocations happen sequentially, which seems like a reasonable assumption and does indeed seem to work.
The same change has been applied to GPU Lightmass as well.
The big change for 5.4 is recognition of the multiple processors.
Like when building from source the maximum number of CPU available is now used at runtime and this means the compiling each shader is allocated to a CPU.
This is similar to the Swarm process and recognises up to 64 CPU if you have at least 64GB memory. UE 5.4 will recognise the Nvidia RTX 4080 Hyper-cooler with 64 CPU.
You will need the latest version of Windows 10 22H2 at least