Bug 198241 - Intel graphics performance regresses after upgrading to kernel 4.14
Summary: Intel graphics performance regresses after upgrading to kernel 4.14
Status: RESOLVED INVALID
Alias: None
Product: Drivers
Classification: Unclassified
Component: Video(Other) (show other bugs)
Hardware: Intel Linux
: P1 high
Assignee: drivers_video-other
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-12-23 21:36 UTC by Julien Langlois
Modified: 2018-01-02 17:10 UTC (History)
1 user (show)

See Also:
Kernel Version: 4.14.*
Subsystem:
Regression: Yes
Bisected commit-id:

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Description Julien Langlois 2017-12-23 21:36:23 UTC 
After switching to kernel 4.14, the screen has flickering and response rate in Xorg is sluggish. The only change is 4.13->4.14. Graphics run smoothly in 4.13.

As a data point, running glxgears produces consistent 60 FPS in 4.13, and around 40 FPS in 4.14 (screen refresh is set to 60Hz in both cases).

- system: "x86_64-linux"
- host os: Linux 4.14.0, NixOS, 18.03pre120540.b8f7027360 (Impala)
- multi-user: yes
- HP Spectre x360 Kaby Lake (13-w063nr)
- Intel(R) HD Graphics 620 (Kaby Lake GT2)
- Issue presents itself with and without compton running

See https://github.com/NixOS/nixpkgs/issues/31999
Comment 1 Julien Langlois 2017-12-31 20:00:39 UTC 
As reported in the other bug report, commit dc911f5bd8aacfcf8aabd5c26c88e04c837a938e introduces the issue by using an "alternate fixed mode."
Comment 2 Paul Menzel 2018-01-02 09:58:33 UTC 
Please paste the output of `xrandr` of 4.13 and 4.14, and attach the rest of the files asked for in [1].

[1] https://01.org/linuxgraphics/documentation/how-report-bugs
Comment 3 Jani Nikula 2018-01-02 17:10:53 UTC 
(In reply to Paul Menzel from comment #2)
> Please paste the output of `xrandr` of 4.13 and 4.14, and attach the rest of
> the files asked for in [1].
> 
> [1] https://01.org/linuxgraphics/documentation/how-report-bugs

And file the bug at https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel
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