Summary: | High latency using GL_FEEDBACK mode | ||
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Product: | Mesa | Reporter: | sancelot <sancelot> |
Component: | Drivers/DRI/i965 | Assignee: | Ian Romanick <idr> |
Status: | RESOLVED NOTABUG | QA Contact: | Intel 3D Bugs Mailing List <intel-3d-bugs> |
Severity: | critical | ||
Priority: | high | CC: | sancelot |
Version: | 11.0 | ||
Hardware: | x86-64 (AMD64) | ||
OS: | Linux (All) | ||
Whiteboard: | |||
i915 platform: | i915 features: | ||
Attachments: | stops when glRenderMode has high latency test case |
This has happened too using GL_ALWAYS_SOFTWARE mode =1 GL_FEEDBACK and GL_SELECT is implemented entirely in software. This is unlikely to be solved any time soon...improving the speed of extremely legacy features isn't high on anyone's priority list. Sorry :( I may not have understood everything...Do you mean glRenderMode(GL_FEEDBACK) is obsolete and I should use new OpenGL features? Regards, Steph Yes, glRenderMode has been deprecated for a long long time. If you want to disable rendering, you can use glEnable(GL_RASTERIZER_DISCARD). Transform feedback (GL 3.0) can record a subset of your vertex shader's outputs into a buffer. Another alternative would be to have your vertex shader write data into a shader storage buffer object (SSBO) (GL 4.3). Unfortunately, both of those options give you data pre-clipping, while glRenderMode(GL_FEEDBACK) gives you data post-clipping. It's a bit awkward because there isn't an exact replacement for the deprecated functionality. The thing is, GL_FEEDBACK and GL_SELECT don't really exist in hardware. We have to emulate them somehow in the driver. Thanks for your reply.. It is very good too know that GL_FEEDBACK is not made by hardware...because I was sure it was using hardware and thus sparing cpu consuming on small processors architecture....and I think I am not standalone.... I will migrate to new OpenGL specifications. |
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Created attachment 126049 [details] stops when glRenderMode has high latency test case Hi, for unknown reasons I noticed my GL application was very slow after migrating to recent platforms. after dissection of application, I found that has happened when using GL_FEEDBACK rendermode. Sometime, it takes very long time. I made a single testcase app that monitors time spent in it to reproduce the problem. Regards steph