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NVIDIA RTX Memory Utility (RTXMU)

Reduce memory consumption with an open-source solution.

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RTXMU combines compaction and suballocation techniques to optimize and reduce memory consumption
RTXMU combines both compaction and suballocation techniques to optimize and reduce memory consumption of acceleration structures (AS) for any DirectX Raytracing or Vulkan Ray Tracing application.

RTXMU Product Benefits

Save Time

RTXMU reduces the time it takes for a developer to integrate compaction and suballocation into an NVIDIA RTX™ title.

Eliminate Wasted Memory

For applications using RTXMU, NVIDIA RTX GPUs get a ~50% reduction in memory footprint.

Prevent Fragmentation

Scenes with thousands of small unique bottom-level acceleration structures (BLAS) benefit greatly from suballocation.

Open Source

To support as many developers as possible, RTXMU is open source and available on GitHub.



Using RTXMU as a Suballocator

  • The AS suballocator works around the 64 kilobyte (KB) / 4 megabyte (MB) buffer-alignment requirement by placing small AS allocations within a larger memory heap.

  • The AS suballocator still needs to fulfil the 256 byte (B) alignment required for AS allocations.

  • If the application requests 4MB or larger suballocation blocks, RTXMU uses placed resources with heaps that can provide 4MB alignment.
  • Sun Temple using RTXMU as a suballocator
    Sun Temple using RTXMU


    Using RTXMU for Compaction

    Zero Day using RTXMU as a compaction.
    Zero Day using RTXMU
  • If the build requests compaction, RTXMU will request the compaction size be written out to a chunk of video memory.

  • Once the compaction size has been copied from video memory to system memory, RTXMU allocates a suballocated compaction buffer to be used as the destination for the compaction copy.

  • The compaction copy takes the original build containing unused memory segments and truncates it down to the smallest memory footprint it can fit in.
  • RTXMU Compaction and Suballocation Analysis

    RTX suballocation analysis chart
    Suballocation can further reduce the amount of AS memory by tightly packing structures together.
    RTX compaction Off/On comparison chart
    NVIDIA reduces AS memory by ~50% when using compaction.

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