Bug 92492 - [SNA] Input lag on QT based applications
Summary: [SNA] Input lag on QT based applications
Status: NEW
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/intel (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Chris Wilson
QA Contact: Intel GFX Bugs mailing list
Depends on:
Reported: 2015-10-16 10:00 UTC by Iván Perdomo
Modified: 2015-10-16 11:16 UTC (History)
0 users

See Also:
i915 platform:
i915 features:

Xorg.0.log (24.45 KB, text/plain)
2015-10-16 10:00 UTC, Iván Perdomo
no flags Details

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Description Iván Perdomo 2015-10-16 10:00:11 UTC
Created attachment 118913 [details]

Thinkpad X230
Kernel: 4.2.3-1-ARCH
Distribution: Arch Linux
Package version: xf86-video-intel 1:2.99.917+478+gdf72bc5-2

There is a lag when using keyboard and mouse on QT based applications (e.g. Skype, VirtualBox) but not in the rest of the system.

The lag is "solved" when using UXA acceleration - 
Comment 1 Chris Wilson 2015-10-16 10:23:18 UTC
Based on previous investigations, my immediate suspicion is that the Qt applications are effectively running unthrottled and build up a long render queue.

Looking at intel-gpu-top or even intel-gpu-overlay should show the GPU maxed out (or nearly), and netstat --unix should (if I am right about the backlog being large enough) show pending bytes from the client to X.
Comment 2 Iván Perdomo 2015-10-16 11:16:56 UTC

How can I produce a log of the GPU usage so i can attach it to the bug report?

Thanks for the support

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