Bug 518908 – x11-drivers/xf86-video-intel-2.99.912 - performance regression with GT3e

• Product: Gentoo Linux
• Status: RESOLVED UPSTREAM

[Description Stian Ellingsen 2014-08-03 08:36:04 UTC]

After updating from .911-r1 to .912, I see a very large decrease in performance. Specifically, in Xonotic 0.7.0, what runs at a full framerate of 60 fps with .911-r1 slows down to 20-30 fps with .912.

Reproducible: Always

Steps to Reproduce:
1. Run a timedemo of e.g. the-big-keybench in Xonotic 0.7.0 with settings just low enough to allow it to mostly play at full framerate under .911-r1.
2. Run the same timedemo with the same settings under .912
Actual Results:  
With .912, the performance seems to be fine for the first few seconds of playback, but then suddenly drops to less than half of the expected framerate.

Expected Results:  
Performance should stay about the same as previously.

Results of a timedemo under .911 and .912 respectively:
10510 frames 175.4414971 seconds 59.9060096 fps, one-second fps min/avg/max: 55 60 61 (336 seconds)
10510 frames 385.4060950 seconds 27.2699372 fps, one-second fps min/avg/max: 19 29 62 (336 seconds)
This was done with a resolution of 2560x1440, 4xAA, 60 Hz refresh rate, vsync, windowed (fullscreen by WM).

CPU: Intel(R) Core(TM) i7-4750HQ
Integrated Graphics Chipset: Intel(R) Iris(TM) Pro Graphics 5200

kernel version: Linux 3.15.7-hardened (also tried 3.13.10-hardened)
window manager: x11-wm/i3-4.7.2 (no compositor)
media-libs/mesa-10.2.4 (also 10.0.4 and 9.2.5-r1)
x11-base/xorg-server-1.15.0 (also 1.14.5)

In addition to x11-drivers/xf86-video-intel-2.99.912, I also tried .912-r1 and .914 with no improvement.

[Comment 1 Matt Turner 2015-02-23 01:03:37 UTC]

I think it's very likely this is fixed in a new version of the driver. If it's
not, please file a bug upstream at bugs.freedesktop.org. We're not prepared to
fix driver issues that aren't fixed upstream.