Public bug reported:
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]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express (v2) Root Complex Integrated Endpoint, MSI 00
DevCap: MaxPayload 128 bytes, PhantFunc 0
ExtTag- RBE+
DevCtl: Report errors: Correctable- Non-Fatal- Fatal-
Unsupported-
RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
MaxPayload 128 bytes, MaxReadReq 128 bytes
DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr-
TransPend-
DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-,
OBFF Not Supported
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-,
OBFF Disabled
Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
Address: fee00018 Data: 0000
Capabilities: [d0] Power Management version 2
Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [100 v1] Process Address Space ID (PASID)
PASIDCap: Exec- Priv-, Max PASID Width: 14
PASIDCtl: Enable- Exec- Priv-
Capabilities: [200 v1] Address Translation Service (ATS)
ATSCap: Invalidate Queue Depth: 00
ATSCtl: Enable-, Smallest Translation Unit: 00
Capabilities: [300 v1] Page Request Interface (PRI)
PRICtl: Enable- Reset-
PRISta: RF- UPRGI- Stopped+
Page Request Capacity: 00008000, Page Request Allocation:
00000000
Kernel driver in use: i915
Kernel modules: i915
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xserver-xorg-core-hwe-18.04 2:1.20.4-1ubuntu3~18.04.1
ProcVersionSignature: Ubuntu 5.3.0-19.20~18.04.2-generic 5.3.1
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_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/zsh
SourcePackage: xorg-server-hwe-18.04
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: xorg-server-hwe-18.04 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug bionic
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https://bugs.launchpad.net/bugs/1853542
Title:
X hangs for several seconds periodically when no GL clients are open
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