Small Lag in Rotated Monitor Display

General system Newbie
1

Hello everyone,

I like to use a vertical monitor as well as a regularly oriented one but I find there’s a small lag in the display of the rotated monitor. Both my monitors are 2560x1440 and I use the proprietary nvidia drivers for my card (gtx 980). Everything displays fine but I would like to know why the lag exists on the vertical monitor. It makes moving the mouse more difficult than the regular monitor because I need to account for the lag. I can easily see the lag when I move a monitor vertically across the span of my two monitors but, interestingly, the lag doesn’t show up when I make a screen recording of the same area - only when I use my desktop regularly. I experience no lag when I have the rotated monitor it oriented regularly in Windows or Linux. Does anyone have any insights into why this is? I don’t experience this on Windows on the same setup.

2

That last statement shoots down my thought on the matter, that perhaps you were getting an artifact of monitor passthrough problems…

So - we need some more info on your setup before any guesses (troubleshooting) can achieve usefulness! A good place to start is to paste the output of inxi -Faz between lines of triple ` (backticks) so as to be clearly formatted.

Incidentally, I run a vertical secondary monitor as well as horizontal one, at different resolution settings (scaled on the vertical) and have no such lag. I’m on XFCE though, I have no idea what you are using.

3

Thanks for the quick reply!

Whoops! I’m using KDE but also noticed the lag in the live boot environment of XFCE when I rotated a monitor.

I wondered if there was something to do with the X server but I don’t know.

Sure, here it is!

System:    Kernel: 5.14.12-arch1-1 x86_64 bits: 64 compiler: gcc v: 11.1.0 
           parameters: BOOT_IMAGE=/@/boot/vmlinuz-linux root=UUID=adacc7d9-3229-46f4-91b4-0b1b81b4ecc3 rw rootflags=subvol=@ 
           quiet resume=UUID=1a3a01c5-aa80-493d-8b2f-def202225da4 loglevel=3 nowatchdog 
           Desktop: KDE Plasma 5.23.1 tk: Qt 5.15.2 wm: kwin_x11 vt: 1 dm: SDDM Distro: EndeavourOS base: Arch Linux 
Machine:   Type: Desktop Mobo: ASUSTeK model: ROG CROSSHAIR VII HERO v: Rev 1.xx serial: <filter> 
           UEFI-[Legacy]: American Megatrends v: 0804 date: 07/09/2018 
CPU:       Info: 8-Core model: AMD Ryzen 7 2700X bits: 64 type: MT MCP arch: Zen+ family: 17 (23) model-id: 8 stepping: 2 
           microcode: 800820D cache: L2: 4 MiB 
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm bogomips: 118208 
           Speed: 1714 MHz min/max: 2200/3700 MHz boost: enabled Core speeds (MHz): 1: 1714 2: 1897 3: 1931 4: 2134 5: 1947 
           6: 1901 7: 1884 8: 1944 9: 1942 10: 1787 11: 1844 12: 1710 13: 2343 14: 3965 15: 1873 16: 1872 
           Vulnerabilities: Type: itlb_multihit status: Not affected 
           Type: l1tf status: Not affected 
           Type: mds status: Not affected 
           Type: meltdown status: Not affected 
           Type: spec_store_bypass mitigation: Speculative Store Bypass disabled via prctl and seccomp 
           Type: spectre_v1 mitigation: usercopy/swapgs barriers and __user pointer sanitization 
           Type: spectre_v2 mitigation: Full AMD retpoline, IBPB: conditional, STIBP: disabled, RSB filling 
           Type: srbds status: Not affected 
           Type: tsx_async_abort status: Not affected 
Graphics:  Device-1: NVIDIA GM204 [GeForce GTX 980] vendor: Gigabyte driver: nvidia v: 470.74 alternate: nouveau,nvidia_drm 
           bus-ID: 0a:00.0 chip-ID: 10de:13c0 class-ID: 0300 
           Device-2: Logitech Webcam C930e type: USB driver: snd-usb-audio,uvcvideo bus-ID: 1-7.1:5 chip-ID: 046d:0843 
           class-ID: 0102 serial: <filter> 
           Display: x11 server: X.Org 1.20.13 compositor: kwin_x11 driver: loaded: nvidia display-ID: :0 screens: 1 
           Screen-1: 0 s-res: 4000x2560 s-dpi: 108 s-size: 940x607mm (37.0x23.9") s-diag: 1119mm (44.1") 
           Monitor-1: DP-0 res: 2560x1440 hz: 60 dpi: 109 size: 597x336mm (23.5x13.2") diag: 685mm (27") 
           Monitor-2: DP-4 res: 1440x2560 hz: 60 
           OpenGL: renderer: NVIDIA GeForce GTX 980/PCIe/SSE2 v: 4.6.0 NVIDIA 470.74 direct render: Yes 
Audio:     Device-1: NVIDIA GM204 High Definition Audio vendor: Gigabyte driver: snd_hda_intel v: kernel bus-ID: 0a:00.1 
           chip-ID: 10de:0fbb class-ID: 0403 
           Device-2: Advanced Micro Devices [AMD] Family 17h HD Audio vendor: ASUSTeK driver: snd_hda_intel v: kernel 
           bus-ID: 0d:00.3 chip-ID: 1022:1457 class-ID: 0403 
           Device-3: Logitech Webcam C930e type: USB driver: snd-usb-audio,uvcvideo bus-ID: 1-7.1:5 chip-ID: 046d:0843 
           class-ID: 0102 serial: <filter> 
           Device-4: Blue Microphones Yeti Stereo Microphone type: USB driver: hid-generic,snd-usb-audio,usbhid 
           bus-ID: 1-7.4:8 chip-ID: b58e:9e84 class-ID: 0300 serial: <filter> 
           Sound Server-1: ALSA v: k5.14.12-arch1-1 running: yes 
           Sound Server-2: JACK v: 1.9.19 running: no 
           Sound Server-3: PulseAudio v: 15.0 running: yes 
           Sound Server-4: PipeWire v: 0.3.38 running: no 
Network:   Device-1: Intel I211 Gigabit Network vendor: ASUSTeK driver: igb v: kernel port: e000 bus-ID: 06:00.0 
           chip-ID: 8086:1539 class-ID: 0200 
           IF: enp6s0 state: up speed: 1000 Mbps duplex: full mac: <filter> 
Bluetooth: Device-1: ASUSTek Broadcom BCM20702A0 Bluetooth type: USB driver: btusb v: 0.8 bus-ID: 1-3:2 chip-ID: 0b05:17cb 
           class-ID: fe01 serial: <filter> 
           Report: rfkill ID: hci0 rfk-id: 0 state: down bt-service: disabled rfk-block: hardware: no software: no 
           address: see --recommends 
Drives:    Local Storage: total: 2.04 TiB used: 73.4 GiB (3.5%) 
           SMART Message: Unable to run smartctl. Root privileges required. 
           ID-1: /dev/nvme0n1 maj-min: 259:0 vendor: Samsung model: SSD 970 EVO 1TB size: 931.51 GiB block-size: 
           physical: 512 B logical: 512 B speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter> rev: 1B2QEXE7 temp: 39.9 C 
           scheme: MBR 
           ID-2: /dev/nvme1n1 maj-min: 259:3 vendor: Samsung model: SSD 970 EVO 1TB size: 931.51 GiB block-size: 
           physical: 512 B logical: 512 B speed: 31.6 Gb/s lanes: 4 type: SSD serial: <filter> rev: 2B2QEXE7 temp: 29.9 C 
           scheme: GPT 
           ID-3: /dev/sda maj-min: 8:0 vendor: PNY model: SSD2SC240G5LC726B104-298 size: 223.57 GiB block-size: 
           physical: 512 B logical: 512 B speed: 6.0 Gb/s type: SSD serial: <filter> rev: BBF0 scheme: GPT 
Partition: ID-1: / raw-size: 862.5 GiB size: 862.5 GiB (100.00%) used: 73.4 GiB (8.5%) fs: btrfs dev: /dev/nvme0n1p1 
           maj-min: 259:1 
           ID-2: /home raw-size: 862.5 GiB size: 862.5 GiB (100.00%) used: 73.4 GiB (8.5%) fs: btrfs dev: /dev/nvme0n1p1 
           maj-min: 259:1 
           ID-3: /var/log raw-size: 862.5 GiB size: 862.5 GiB (100.00%) used: 73.4 GiB (8.5%) fs: btrfs dev: /dev/nvme0n1p1 
           maj-min: 259:1 
Swap:      Kernel: swappiness: 60 (default) cache-pressure: 100 (default) 
           ID-1: swap-1 type: partition size: 69.01 GiB used: 0 KiB (0.0%) priority: -2 dev: /dev/nvme0n1p2 maj-min: 259:2 
Sensors:   System Temperatures: cpu: 41.5 C mobo: N/A gpu: nvidia temp: 46 C 
           Fan Speeds (RPM): N/A gpu: nvidia fan: 27% 
Info:      Processes: 387 Uptime: 1h 1m wakeups: 0 Memory: 62.73 GiB used: 4.9 GiB (7.8%) Init: systemd v: 249 tool: systemctl 
           Compilers: gcc: 11.1.0 clang: 12.0.1 Packages: pacman: 1434 lib: 295 Shell: Bash v: 5.1.8 running-in: konsole 
           inxi: 3.3.06

Edit: Noticed some data was missing so I installed those packages and reran inxi -Faz.

Edit2: I notice Monitor-2 (the rotated one) doesn’t have the same amount of information present as Monitor-1. Could this be contributing to the problem?

Edit3: Monitor-2 shows all information if it’s oriented regularly:

           Monitor-1: DP-0 res: 2560x1440 hz: 60 dpi: 109 size: 597x336mm (23.5x13.2") diag: 685mm (27") 
           Monitor-2: DP-4 res: 2560x1440 hz: 60 dpi: 109 size: 597x336mm (23.5x13.2") diag: 685mm (27")
4

So, found a couple more things that may help narrow things down. I notice identical lag on both monitors when I have “Force Full Composition Pipeline” set on both. What’s nice is that I no longer have a difference in mouse movement when using one monitor or the other. What isn’t is that now my non-rotated monitor lags as much as the rotated one. I don’t find a difference having “Force Full Composition Pipeline” enabled on the rotated monitor or not - it lags all the same.

I played around with the resolution of my rotated monitor and found no difference in lag even when I lowered its resolution to 720x1280.

Interestingly, all visual lag disappears when I boot KDE into Wayland. Unfortunately, Wayland seems to be buggy for my uses and it was difficult to use.

This seems like a problem with X server. Is https://launchpad.net/xorg-server the correct place to file a bug report?