Qt 6 CUDA to OpenGL performance loss
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wrote on 21 Feb 2025, 18:09 last edited by
We have an application that was running 5.15.X and are in the process of upgrading to 6.8.X.
During our development in Qt5, we implemented NVDEC to decode movie files and used CUDA's excellent cuGrapghicsGLRegisterBuffer to copying from the cuda context into OGL textures provided by Qt.
After upgrading, we 're seeing a huge spike in the CUDA device-to-device copy operation and we're wondering if something about the new RHI or other interface in Qt6 is causing the copy to switch contexts or something of the sort. We've lost a significant amount of performance but haven't changed the CUDA code in any way, only the Qt version.
Any insight into how the render interfaces might have effected this would be great. We've confirmed that all RHI settings are OpenGL (desktop) via QSG_INFO=1 and the qt.rhi is reporting OpenGL and right graphics card.
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Hi and welcome to devnet,
Intriguing issue ! I would recommend bringing it to the interest mailing list. You'll find there Qt developers/maintainers. This forum is more user oriented.
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