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Delayed display output when using GLX backend and VSYNC on AMD #1345

@christian-heusel

Description

@christian-heusel

Platform

Arch Linux (Rolling) amd64

GPU, drivers, and screen setup

glxinfo -B
name of display: :0
display: :0  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: AMD (0x1002)
    Device: AMD Radeon Graphics (radeonsi, renoir, LLVM 18.1.8, DRM 3.58, 6.11.1-rc1-1home) (0x164c)
    Version: 24.2.3
    Accelerated: yes
    Video memory: 1024MB
    Unified memory: no
    Preferred profile: core (0x1)
    Max core profile version: 4.6
    Max compat profile version: 4.6
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.2
Memory info (GL_ATI_meminfo):
    VBO free memory - total: 384 MB, largest block: 384 MB
    VBO free aux. memory - total: 6947 MB, largest block: 6947 MB
    Texture free memory - total: 384 MB, largest block: 384 MB
    Texture free aux. memory - total: 6947 MB, largest block: 6947 MB
    Renderbuffer free memory - total: 384 MB, largest block: 384 MB
    Renderbuffer free aux. memory - total: 6947 MB, largest block: 6947 MB
Memory info (GL_NVX_gpu_memory_info):
    Dedicated video memory: 1024 MB
    Total available memory: 8425 MB
    Currently available dedicated video memory: 384 MB
OpenGL vendor string: AMD
OpenGL renderer string: AMD Radeon Graphics (radeonsi, renoir, LLVM 18.1.8, DRM 3.58, 6.11.1-rc1-1home)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 24.2.3-arch1.1
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 4.6 (Compatibility Profile) Mesa 24.2.3-arch1.1
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile

OpenGL ES profile version string: OpenGL ES 3.2 Mesa 24.2.3-arch1.1
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

Environment

i3 version 4.23 (which has gaps support merged)

picom version

$ picom --version                                  
v12.1 (/startdir/picom revision c321da4)
Diagnostics
$ picom --diagnostics --config ~/.config/i3/picom.conf 
[ 09/29/2024 12:56:52.693 parse_config_libconfig WARN ] The refresh-rate option has been deprecated. Please remove it from your configuration file. If you encounter any problems without this feature, please feel free to open a bug report
[ 09/29/2024 12:56:52.693 c2_parse_target WARN ] Type specifier is deprecated. Type "a" specified on target "_NET_WM_STATE" will be ignored, you can remove it.
[ 09/29/2024 12:56:52.693 c2_parse_target WARN ] Format specifier is deprecated. Format "32" specified on target "_NET_WM_STATE" will be ignored, you can remove it.
[ 09/29/2024 12:56:52.693 c2_parse_target WARN ] Type specifier is deprecated. Type "c" specified on target "_GTK_FRAME_EXTENTS" will be ignored, you can remove it.
[ 09/29/2024 12:56:52.693 c2_parse_target WARN ] Type specifier is deprecated. Type "c" specified on target "_GTK_FRAME_EXTENTS" will be ignored, you can remove it.
**Version:** v12.1 (/startdir/picom revision c321da4)

### Extensions:

* Shape: Yes
* RandR: Yes
* Present: Present

### Misc:

* Use Overlay: No

* Config file specified: /home/chris/.config/i3/picom.conf
* Config file used: /home/chris/.config/i3/picom.conf

### Drivers (inaccurate):

modesetting

### Backend: glx

* Driver vendors:
 * GLX: Mesa Project and SGI
 * GL: AMD
* GL renderer: AMD Radeon Graphics (radeonsi, renoir, LLVM 18.1.8, DRM 3.58, 6.11.1-rc1-1home)
* Accelerated: 1
[ 09/29/2024 12:56:52.933 egl_init WARN ] The egl backend is still experimental, use with care.

### Backend: egl

* Driver vendors:
 * EGL: Mesa Project
 * EGL driver: radeonsi
 * GL: AMD
* GL renderer: AMD Radeon Graphics (radeonsi, renoir, LLVM 18.1.8, DRM 3.58, 6.11.1-rc1-1home)

Configuration:

Configuration file
# Thank you code_nomad: http://9m.no/ꪯ鵞
# and Arch Wiki contributors: https://wiki.archlinux.org/index.php/Compton

#################################
# Backend
#################################

# Backend to use: "xrender" or "glx".
# GLX backend is typically much faster but depends on a sane driver.
backend = "glx";
# backend = "xrender"

#################################
# GLX backend
#################################

glx-no-stencil = true;

# GLX backend: Copy unmodified regions from front buffer instead of redrawing them all.
# My tests with nvidia-drivers show a 10% decrease in performance when the whole screen is modified,
# but a 20% increase when only 1/4 is.
# My tests on nouveau show terrible slowdown.
glx-copy-from-front = false;

# GLX backend: Use MESA_copy_sub_buffer to do partial screen update.
# My tests on nouveau shows a 200% performance boost when only 1/4 of the screen is updated.
# May break VSync and is not available on some drivers.
# Overrides --glx-copy-from-front.
# glx-use-copysubbuffermesa = true;

# GLX backend: Avoid rebinding pixmap on window damage.
# Probably could improve performance on rapid window content changes, but is known to break things on some drivers (LLVMpipe).
# Recommended if it works.
# glx-no-rebind-pixmap = true;

# GLX backend: GLX buffer swap method we assume.
# Could be undefined (0), copy (1), exchange (2), 3-6, or buffer-age (-1).
# undefined is the slowest and the safest, and the default value.
# copy is fastest, but may fail on some drivers,
# 2-6 are gradually slower but safer (6 is still faster than 0).
# Usually, double buffer means 2, triple buffer means 3.
# buffer-age means auto-detect using GLX_EXT_buffer_age, supported by some drivers.
# Useless with --glx-use-copysubbuffermesa.
# Partially breaks --resize-damage.
# Defaults to undefined.
#glx-swap-method = "undefined";

#################################
# Shadows
#################################

# Enabled client-side shadows on windows.
shadow = false;
# The blur radius for shadows. (default 12)
shadow-radius = 5;
# The left offset for shadows. (default -15)
shadow-offset-x = -5;
# The top offset for shadows. (default -15)
shadow-offset-y = -5;
# The translucency for shadows. (default .75)
shadow-opacity = 0.5;

log-level = "warn";
#change your username here
#log-file = "/home/erik/.config/compton.log";

# Set if you want different colour shadows
# shadow-red = 0.0;
# shadow-green = 0.0;
# shadow-blue = 0.0;

# The shadow exclude options are helpful if you have shadows enabled. Due to the way compton draws its shadows, certain applications will have visual glitches
# (most applications are fine, only apps that do weird things with xshapes or argb are affected).
# This list includes all the affected apps I found in my testing. The "! name~=''" part excludes shadows on any "Unknown" windows, this prevents a visual glitch with the XFWM alt tab switcher.
shadow-exclude = [
    "! name~=''",
    "name = 'Notification'",
    "name = 'Plank'",
    "name = 'Docky'",
    "name = 'Kupfer'",
    "name = 'xfce4-notifyd'",
    "name *= 'VLC'",
    "name *= 'compton'",
    "name *= 'Chromium'",
    "name *= 'Chrome'",
    "class_g = 'Firefox' && argb",
    "class_g = 'Conky'",
    "class_g = 'Kupfer'",
    "class_g = 'Synapse'",
    "class_g ?= 'Notify-osd'",
    "class_g ?= 'Cairo-dock'",
    "class_g = 'Cairo-clock'",
    "class_g ?= 'Xfce4-notifyd'",
    "class_g ?= 'Xfce4-power-manager'",
    "_GTK_FRAME_EXTENTS@:c",
    "_NET_WM_STATE@:32a *= '_NET_WM_STATE_HIDDEN'"
];
# Avoid drawing shadow on all shaped windows (see also: --detect-rounded-corners)
shadow-ignore-shaped = false;

#################################
# Opacity
#################################

inactive-opacity = 1;
active-opacity = 1;
frame-opacity = 1;
inactive-opacity-override = false;

# Dim inactive windows. (0.0 - 1.0)
# inactive-dim = 0.2;
# Do not let dimness adjust based on window opacity.
# inactive-dim-fixed = true;
# Blur background of transparent windows. Bad performance with X Render backend. GLX backend is preferred.
# blur-background = true;
# Blur background of opaque windows with transparent frames as well.
# blur-background-frame = true;
# Do not let blur radius adjust based on window opacity.
blur-background-fixed = false;
blur-background-exclude = [
    "window_type = 'dock'",
    "window_type = 'desktop'",
    "_GTK_FRAME_EXTENTS@:c"
];

#################################
# Fading
#################################

# Fade windows during opacity changes.
fading = true;
# The time between steps in a fade in milliseconds. (default 10).
fade-delta = 2;
# Opacity change between steps while fading in. (default 0.028).
fade-in-step = 0.03;
# Opacity change between steps while fading out. (default 0.03).
fade-out-step = 0.03;
# Fade windows in/out when opening/closing
# no-fading-openclose = true;

# Specify a list of conditions of windows that should not be faded.
fade-exclude = [ ];

#################################
# Other
#################################

# Try to detect WM windows and mark them as active.
mark-wmwin-focused = true;
# Mark all non-WM but override-redirect windows active (e.g. menus).
mark-ovredir-focused = true;
# Use EWMH _NET_WM_ACTIVE_WINDOW to determine which window is focused instead of using FocusIn/Out events.
# Usually more reliable but depends on a EWMH-compliant WM.
use-ewmh-active-win = true;
# Detect rounded corners and treat them as rectangular when --shadow-ignore-shaped is on.
detect-rounded-corners = true;

# Detect _NET_WM_OPACITY on client windows, useful for window managers not passing _NET_WM_OPACITY of client windows to frame windows.
# This prevents opacity being ignored for some apps.
# For example without this enabled my xfce4-notifyd is 100% opacity no matter what.
detect-client-opacity = true;

# Specify refresh rate of the screen.
# If not specified or 0, compton will try detecting this with X RandR extension.
refresh-rate = 0;

# Vertical synchronization: match the refresh rate of the monitor
# this breaks transparency in virtualbox - put a "#" before next line to fix that
vsync = true;

# Enable DBE painting mode, intended to use with VSync to (hopefully) eliminate tearing.
# Reported to have no effect, though.
dbe = false;

# Limit compton to repaint at most once every 1 / refresh_rate second to boost performance.
# This should not be used with --vsync drm/opengl/opengl-oml as they essentially does --sw-opti's job already,
# unless you wish to specify a lower refresh rate than the actual value.
#sw-opti = true;

# Unredirect all windows if a full-screen opaque window is detected, to maximize performance for full-screen windows, like games.
# Known to cause flickering when redirecting/unredirecting windows.
unredir-if-possible = false;

# Specify a list of conditions of windows that should always be considered focused.
focus-exclude = [ ];

# Use WM_TRANSIENT_FOR to group windows, and consider windows in the same group focused at the same time.
detect-transient = true;
# Use WM_CLIENT_LEADER to group windows, and consider windows in the same group focused at the same time.
# WM_TRANSIENT_FOR has higher priority if --detect-transient is enabled, too.
detect-client-leader = true;

#################################
# Window type settings
#################################

wintypes:
{
  tooltip = { fade = true; shadow = true; opacity = 0.9; focus = true;};
  dock = { shadow = false; }
  dnd = { shadow = false; }
  popup_menu = { opacity = 0.9; }
  dropdown_menu = { opacity = 0.9; }
};

######################
# XSync
# See: https://github.com/yshui/compton/commit/b18d46bcbdc35a3b5620d817dd46fbc76485c20d
######################

# Use X Sync fence to sync clients' draw calls. Needed on nvidia-drivers with GLX backend for some users.
xrender-sync-fence = true;

Steps of reproduction

  1. Use picom with the glx backend and vsync enabled
  2. Use some program (in my case neomutt)
  3. observe that it's lagging from time to time for normal usage

You can i.e. see in the following videos that the clicks of my keyboard usually result in an immediate change but sometimes it needs some time until something happens:

2024-09-29.12-07-48.mp4

Expected behavior

Everything feels snappy.

Current Behavior

Have output lags from time to time

Other details

See the video above.


cc @Antiz96

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