Out of Core Textures implementation in V-Ray GPU

[Muhammed_Hamed]

Introduction,

With V-Ray 6 update 2 for Maya and Houdini (and the latest Hotifx for 3Ds Max), V-Ray GPU is able to offload Textures to system memory, to lower GPU memory usage significantly with little impact on performance. This is an entirely new implementation of Out Of Core(the old implementation is deprecated and removed from the UI). This new feature should be used for rendering massive scenes with many high-resolution textures, in which GPU memory is insufficient to render the scene. If your scene data fits in the memory of your GPU, it is best to stick to GPU memory for rendering.
To use OOC Textures, enable Use System Memory For Textures option in the UI
When enabled, all textures that are bigger than 1 mb in size will be allocated in CPU memory and becomes accessible to all rendering devices.

Note, OOC Textures is supported in both CUDA and RTX engines, and could be used with hybrid Rendering
Note, V-Ray GPU uses PCIE bandwidth to move texture data to system memory. PCIE 4.0/5.0(in newer CPUs and motherboards) will show little impact on rendering performance
Note, All Texture modes(Resize, Compressed..etc) are greyed out when OOC is enabled

Maya,



3Ds Max,



Testing,

We have tested 3 scenes on an RTX 4090 using Progressive mode, the results are double checked. To ensure accurate results. All tests run for at least 5-minutes

First Scene, Winter_Apartment

• GPU memory usage is reduced from 17 GB to 5.1 GB
• Render time is 655 seconds and 742 seconds when OOC is enabled, 12% slowdown

Second Scene, Interior_005

• GPU memory usage is reduced from 22 GB to 4.8 GB
• Render time is 550 seconds and 681 seconds when OOC is enabled, 23% slowdown

Third Scene, Forest_01

• GPU memory usage is reduced from 16 GB to 4.9 GB
• Render time is 371 seconds and 435seconds when OOC is enabled, 23% slowdown

Note, For multi-GPU setups, the performance hit could be higher. This is something we plan on improving in the future

Monitoring Texture memory,

Windows Task Manager, the Texture memory when OOC is enabled will be reported under Shared GPU memory



V-Ray Log, will report the Texture memory if OOC is enabled



Note, the stats tab doesn't show information about OOC yet. This is something we plan to improve in the future

Best,
Muhammed