Render thread hitches on mip streaming for particle systems

Development Rendering
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7

Hi,

I looked into this a bit more and there may be some additional options if keeping particle textures resident is not possible:

  • Using r.Streaming.AmortizeCPUToGPUCopy and r.Streaming.MaxNumTexturesToStreamPerFrame should indeed be advantageous (there is a bit more info from Epic on which settings to use for different texture qualities at [this [Content removed]
  • Another option might be to enable r.Streaming.AllowParallelStreamingRenderAssets when multiple cores are available
  • below is a potential configuration for CVars related to streaming which is optimised to mitigate stutters. You may have to experiment with the MaxNumTexturesToStreamPerFrame and NumStaticComponentsProcessedPerFrame settings to see what works best for your project. This page may be helpful to explain some of the CVars (you may have found it already)

r.Streaming.Boost=1 ; Extra optimizations for streaming r.Streaming.MinMipForSplitRequest=0 ; Additional streaming tweaks for stutter fixes r.Streaming.HiddenPrimitiveScale=1 ; Additional streaming tweaks for stutter fixes r.Streaming.AmortizeCPUToGPUCopy=1 ; Additional streaming tweaks for stutter fixes r.Streaming.MaxNumTexturesToStreamPerFrame=100 ; Additional streaming tweaks for stutter fixes r.Streaming.NumStaticComponentsProcessedPerFrame=100 ; Additional streaming tweaks for stutter fixes r.Streaming.FramesForFullUpdate=1 ; Additional streaming tweaks for stutter fixes s.AsyncLoadingThreadEnabled=1 ; Additional streaming tweaks for stutter fixes s.AsyncLoadingTimeLimit=2 ; Additional streaming tweaks for stutter fixes s.LevelStreamingActorsUpdateTimeLimit=2 ; Additional streaming tweaks for stutter fixes s.UnregisterComponentsTimeLimit=2 ; Additional streaming tweaks for stutter fixes s.AsyncLoadingUseFullTimeLimit=0 ; Additional streaming tweaks for stutter fixes s.IoDispatcherCacheSizeMB=256 ; Additional streaming tweaks for stutter fixes s.LevelStreamingComponentsRegistrationGranularity=1 ; Additional streaming tweaks for stutter fixes s.LevelStreamingComponentsUnregistrationGranularity=1 ; Additional streaming tweaks for stutter fixes s.MaxIncomingRequestsToStall=1 ; Additional streaming tweaks for stutter fixes s.MaxReadyRequestsToStallMB=0 ; Additional streaming tweaks for stutter fixes s.MinBulkDataSizeForAsyncLoading=0 ; Additional streaming tweaks for stutter fixes s.PriorityAsyncLoadingExtraTime=1 ; Additional streaming tweaks for stutter fixes s.PriorityLevelStreamingActorsUpdateExtraTime=0 ; Additional streaming tweaks for stutter fixes

Hopefully this helps. Please let me know if it works.

Thanks,

Sam