| Summary: | [r300g] xscreensaver "endgame" hack runs much slower than under classic Mesa. | ||
|---|---|---|---|
| Product: | Mesa | Reporter: | Chris Rankin <rankincj> |
| Component: | Drivers/DRI/r300 | Assignee: | Corbin Simpson <MostAwesomedude> |
| Status: | RESOLVED WONTFIX | QA Contact: | |
| Severity: | normal | ||
| Priority: | medium | ||
| Version: | git | ||
| Hardware: | x86 (IA32) | ||
| OS: | Linux (All) | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
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Description
Chris Rankin
2010-03-24 15:34:16 UTC
This is with vanilla Linux 2.6.33.1, libdrm-2.4.18 and xf86-drv-ati from git. The glschool screensaver behaves similarly (when invoked from the command line as a standalone application): Classic Mesa: Load ~40% and ~30 fps Gallium: Load ~50% and ~25 fps This screensaver is in package xscreensaver-gl-extras-5.10-6.1.fc12.1.i686 Hm. It hits the immediate drawing path a lot. Changing the immd threshold from 10 to 6 fixes the colors, but slows down rendering even more. This probably warrants further examination. Renaming for easier finding. Profile shows nothing out of the ordinary. We must be making bad decisions somewhere else along the line. FWIW there are several software fallbacks buried in st/mesa which can't be resolved in the driver. One of them is glCopyTexImage for formats other than GL_RGBA and GL_RGB, and when the source and destination format don't match. Also, glean/depthStencil fallbacks to software too. With a fresh 2.6.33.3 kernel and xorg-xf86-drv-ati from git, I now get: Classic Mesa: 14 - 20 fps (>= 60% load) Gallium: 2 - 4.5 fps (> 90% load) The screensaver package has moved on to xscreensaver-gl-extras-5.11-1.fc12.i686 Some news. Endgame uses immediate mode for rendering tens of thousands of triangles, which is always slow. r300g happens to suffer more because it hits the hardware immediate mode path pretty much all the time. st/mesa seems to call draw_arrays once for each triangle, which is totally crazy. More news. For each model, the screensaver stores each triangle in a separate display list. When rendering, it calls all display lists in a for loop. Mesa is not (and won't be) optimized for such a retarded OpenGL usage. Closing. (In reply to comment #8) > Mesa is not (and won't be) optimized for such a retarded OpenGL usage. OK, but I'm currently more worried about bug 28656 ;-). This screensaver may be inefficient, but it still shouldn't crash. |
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