Bug 187521

Summary:	Graphics Regression: Window dragging, opening very slow and laggy
Product:	Drivers	Reporter:	Alex Spitzer (aes368)
Component:	Video(Other)	Assignee:	drivers_video-other
Status:	RESOLVED INVALID
Severity:	normal	CC:	mail
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	4.8	Subsystem:
Regression:	Yes	Bisected commit-id:
Attachments:	A zip file of dmesg logs, the bisect log, ver_linux logs, lspci log, and two videos git bisect log Screen capture showing slowness Screen capture showing expected performance for comparison dmesg after booting the bad kernel dmesg after booting the good kernel ver_linux output from bad kernel ver_linux output from good kernel lspci output

Description Alex Spitzer 2016-11-12 22:57:33 UTC

Created attachment 244251 [details]
A zip file of dmesg logs, the bisect log, ver_linux logs, lspci log, and two videos

Hello,

I noticed that in newer Linux 4.8 kernels the desktop was performing very poorly. Opening windows (such as xterm) takes a very long time, as does dragging windows around the screen and resizing. Alt-tab also has significant lag, with an exception being when switching between two fullscreen xterm windows.

I am using IceWM as a window manager on Arch Linux.

After doing a bisection, I found that the issue is not present in 194dc870 and is present on 554828ee, which does not touch the i915 driver directly (https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=554828ee0db41618d101d9549db8808af9fd9d65). The bisection was done using the following AUR package: https://aur.archlinux.org/packages/linux-git/

I have attached one video showing performance with the problem and one video showing performance without the problem, as well as dmesg and other logs. I'll be happy to provide more info to narrow down the problem.

Here is the Arch Linux forums thread this is first mentioned in.
https://bbs.archlinux.org/viewtopic.php?id=219349

Comment 1 Alex Spitzer 2016-11-15 02:18:17 UTC

Created attachment 244461 [details]
git bisect log

Comment 2 Alex Spitzer 2016-11-15 02:21:31 UTC

Created attachment 244471 [details]
Screen capture showing slowness

Not visible, but there is significant delay (about 1 - 1.5 seconds) between the open terminal key shortcut and the terminal appearing.

Comment 3 Alex Spitzer 2016-11-15 02:22:23 UTC

Created attachment 244481 [details]
Screen capture showing expected performance for comparison

Comment 4 Alex Spitzer 2016-11-15 02:23:13 UTC

Created attachment 244491 [details]
dmesg after booting the bad kernel

Comment 5 Alex Spitzer 2016-11-15 02:23:40 UTC

Created attachment 244501 [details]
dmesg after booting the good kernel

Comment 6 Alex Spitzer 2016-11-15 02:25:02 UTC

Created attachment 244511 [details]
ver_linux output from bad kernel

Comment 7 Alex Spitzer 2016-11-15 02:25:26 UTC

Created attachment 244521 [details]
ver_linux output from good kernel

Comment 8 Alex Spitzer 2016-11-15 02:25:54 UTC

Created attachment 244531 [details]
lspci output

Comment 9 Jani Nikula 2016-11-16 15:31:19 UTC

Please file drm/i915 bugs at https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel

Comment 10 Alex Spitzer 2016-11-16 20:07:32 UTC

https://bugs.freedesktop.org/show_bug.cgi?id=98755