X hangs for several seconds periodically when no GL clients are open
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
xorg-server-hwe-18.04 (Ubuntu) |
Expired
|
Undecided
|
Unassigned |
Bug Description
Not sure if this is an issue with the X server or with the kernel i915 module, so I'm starting with X.
The system is a Thinkpad X1 Carbon, Gen 7. Details on the graphics hardware (from lspci -vv) are below. BIOS is up-to-date as of Nov. 21.
The symptom is that X will not redraw screen state for several seconds at a time under certain circumstances. Characters typed into a window, or an application that attempts to redraw regularly, are the easiest demonstration of this. E.g. running 'vmstat 1' in a terminal (which should print one line of text every second), I see no activity for roughly 5 seconds, and then all 5 seconds worth of content are printed.
Generating some activity with the mouse/trackpad seems to trigger a refresh before the full time delay expires.
This problem does *not* occur in the default Ubuntu GNOME environment. It appears that it only occurs when there are no GL clients running. In a minimal "failsafe" X session, it is reproducible 100% of the time. In a failsafe session with the "glxdemo" program from the "mesa-utils" package installed, the problem does not occur. I suspect that there's enough GL usage in the standard GNOME configuration that this doesn't affect most users, but my default X session doesn't use much GL.
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (Whiskey Lake) (rev 02) (prog-if 00 [VGA controller])
Subsystem: Lenovo Device 2292
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0
Interrupt: pin A routed to IRQ 130
Region 0: Memory at e9000000 (64-bit, non-prefetchable) [size=16M]
Region 2: Memory at c0000000 (64-bit, prefetchable) [size=256M]
Region 4: I/O ports at 2000 [size=64]
[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
Kernel driver in use: i915
Kernel modules: i915
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xserver-
ProcVersionSign
Uname: Linux 5.3.0-19-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
Date: Thu Nov 21 17:12:15 2019
InstallationDate: Installed on 2019-11-15 (6 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
ProcEnviron:
TERM=xterm
PATH=(custom, user)
XDG_RUNTIME_
LANG=en_US.UTF-8
SHELL=/bin/zsh
SourcePackage: xorg-server-
UpgradeStatus: No upgrade log present (probably fresh install)
Does booting with 'i915.enable_psr=0' help?