Xorg actually doesn't have support for synchronizing multiple screens
very well. The compositor can only paint all screens at once, and then
the Xorg drivers have to output their areas at separate times later.
The 'modeset' Xorg driver will just sync to one and tear on the others.
And I am not sure how radeon/amdgpu are expected to interplay. If they
support a TearFree feature then that means at least one of them has to
delay each frame, which you might see as lag. Also, if the monitors have
different refresh rates then there's no guarantee Xorg will sync to the
fastest one -- it might sync to the slowest, which has to be worked
around in the drivers.
I suggest the first thing to investigate here is to see if you can get
both GPUs using the same driver (from the kernel onward). Because using
both 'radeon' and 'amdgpu' at the same time might be causing this.
GNOME Wayland sessions don't have this problem at all because there is
no Xorg and it schedules each display separately.
** Package changed: xorg-server (Ubuntu) => xserver-xorg-video-amdgpu
(Ubuntu)
** Also affects: xserver-xorg-video-ati (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1923153
Title:
Display output laggy from iGPU when operating on desktop with
attaching AMD R7 430 graphic (dGPU)
Status in OEM Priority Project:
Confirmed
Status in xserver-xorg-video-amdgpu package in Ubuntu:
New
Status in xserver-xorg-video-ati package in Ubuntu:
New
Bug description:
[Steps to reproduce this issue]
1. Install a focal base image
2. Attach an AMD R7 430 graphic as dGPU without connecting any monitor on it.
3. Attach DP monitor on iGPU (no matter the iGPU is Intel(i915), or
AMD(amdgpu)).
4. After logging it, the display shows laggy.
[Additional information]
1. doesn't see this issue if selecting 'Wayland'
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xserver-xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.10.0-1019.20-oem 5.10.18
Uname: Linux 5.10.0-1019-oem x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
Date: Fri Apr 9 16:23:42 2021
DistUpgraded: Fresh install
DistributionChannelDescriptor:
# This is the distribution channel descriptor for the OEM CDs
# For more information see
http://wiki.ubuntu.com/DistributionChannelDescriptor
canonical-oem-stella-focal-amd64-20210324-1458+pc-stella-cmit-focal-amd64+X00
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
Advanced Micro Devices, Inc. [AMD/ATI] Oland [Radeon HD 8570 / R7 240/340 /
Radeon 520 OEM] [1002:6611] (rev 87) (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Oland [Radeon HD 8570 / R7 240/340 /
Radeon 520 OEM] [103c:3375]
Advanced Micro Devices, Inc. [AMD/ATI] Renoir [1002:1636] (rev da) (prog-if
00 [VGA controller])
Subsystem: Hewlett-Packard Company Renoir [103c:872b]
InstallationDate: Installed on 2021-04-09 (0 days ago)
InstallationMedia: Ubuntu 20.04 "Focal" - Build amd64 LIVE Binary
20210324-23:53
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.10.0-1019-oem
root=UUID=027c2398-aef7-43d2-a339-6a2163287914 ro quiet splash vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/30/2020
dmi.bios.release: 2.0
dmi.bios.vendor: HP
dmi.bios.version: S09 Ver. 02.02.00
dmi.board.name: 872B
dmi.board.vendor: HP
dmi.board.version: KBC Version 09.94.00
dmi.chassis.type: 3
dmi.chassis.vendor: HP
dmi.ec.firmware.release: 9.148
dmi.modalias:
dmi:bvnHP:bvrS09Ver.02.02.00:bd12/30/2020:br2.0:efr9.148:svnHP:pn:pvr:rvnHP:rn872B:rvrKBCVersion09.94.00:cvnHP:ct3:cvr:
dmi.product.family: 103C_53307F HP EliteDesk
dmi.sys.vendor: HP
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.102-1ubuntu1~20.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 20.2.6-0ubuntu0.20.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.9-2ubuntu1.2~20.04.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel
2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1
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