How to debug slowness

[ikouchiha47]

What Operating System(s) are you running on?

Linux X11

Which Wayland compositor or X11 Window manager(s) are you using?

i3

WezTerm version

20240203-110809-5046fc22-gentoo

Ask your question!

Wezterm is pretty slow on my:

• i3
• gentoo
• Intel i7-8550U CPU @ 1.80GHz
• 15Gi RAM

I have tried using software emulation, I have tried webgpu (which I am not sure if it makes sense without a gpu). I removed all fonts and stuff, but still it is way to slow. And gets slower as time goes on. Config

How to debug this? Also, i was wondering if my system configuration is slow for wezterm, or am I missing any drivers. On the MAC M1 it works fine.

It's slower than terminator, but its supposed to be as fast as st. Something is wrong.

Logs from linux

Debug Overlay
wezterm version: 20240203-110809-5046fc22-gentoo x86_64-unknown-linux-gnu
Window Environment: X11 i3
Lua Version: Lua 5.4
WebGPU: name=llvmpipe (LLVM 18.1.8, 256 bits), device_type=Cpu, backend=Gl, vendor=65541, device=0
Enter lua statements or expressions and hit Enter.
Press ESC or CTRL-D to exit
08:03:46.344 WARN window::os::x11::connection > Unable to resolve appearance using xdg-desktop-portal: get_appearance.read_setting: Reading xdg-portal org.freedesktop.appearance color-scheme: org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.portal.Desktop was not provided by any .service files
> wezterm.gui.enumerate_gpus()
[
    {
        "backend": "Gl",
        "device": 0,
        "device_type": "Cpu",
        "name": "llvmpipe (LLVM 18.1.8, 256 bits)",
        "vendor": 65541,
    },
]

wezterm --config periodic_stat_logging=10 &
kaiju8@kaiju8 /h/d/d/devtools (master)> libEGL warning: DRI2: failed to authenticate
libEGL warning: MESA-LOADER: failed to open zink: /usr/lib64/dri/zink_dri.so: cannot open shared object file: No such file or directory (search paths /usr/lib64/dri, suffix _dri)

libEGL warning: DRI2: failed to authenticate
libEGL warning: MESA-LOADER: failed to open zink: /usr/lib64/dri/zink_dri.so: cannot open shared object file: No such file or directory (search paths /usr/lib64/dri, suffix _dri)

08:09:28.767  WARN   window::os::x11::connection > Unable to resolve appearance using xdg-desktop-portal: get_appearance.read_setting: Reading xdg-portal org.freedesktop.appearance color-scheme: org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.portal.Desktop was not provided by any .service files

STAT                                    current p50 p75 p95
Key(glyph_cache.glyph_cache.hit.rate)   0       189 189 189
Key(glyph_cache.glyph_cache.miss.rate)  0       41  41  41 
Key(gui.paint.impl.rate)                0       3   10  10 
Key(line_quad_cache.hit.rate)           0       58  583 583
Key(line_quad_cache.miss.rate)          0       58  116 116
Key(line_state_cache.hit.rate)          0       174 527 527
Key(line_to_ele_shape_cache.hit.rate)   0       64  117 117
Key(line_to_ele_shape_cache.miss.rate)  0       4   4   4  
Key(mux.pane_output_event.rate)         0       1   1   1  
Key(read_from_pane_pty.bytes.rate)      0       399 399 399
Key(send_actions_to_mux.rate)           0       5   5   5  
Key(shape_cache.hit.rate)               0       18  63  63 
Key(shape_cache.miss.rate)              0       24  24  24 
Key(window.atlas.allocate.success.rate) 0       1   43  43 

STAT                                             p50      p75      p95     
Key(cached_cluster_shape)                        1.87µs   6.11µs   512.00µs
Key(executor.spawn_delay)                        313.34µs 3.75ms   106.95ms
Key(gui.paint.impl)                              2.21ms   2.54ms   36.70ms 
Key(paint_pane.lines)                            344.06µs 393.22µs 16.71ms 
Key(quad.map)                                    36.86µs  38.91µs  51.20µs 
Key(quad_buffer_apply)                           97.00ns  105.00ns 1.04µs  
Key(render_screen_line)                          799.00ns 895.00ns 134.14µs
Key(send_actions_to_mux.perform_actions.latency) 41.22µs  72.19µs  153.60µs
Key(shape.harfbuzz)                              88.06µs  175.10µs 458.75µs
Key(window.atlas.allocate.latency)               10.11µs  12.99µs  33.79µs 

STAT COUNT

[ghost]

🤍✨🙏

[ikouchiha47]

Okay. This is what I did on my gentoo. The error was there, but I didn't think it would be as much an issue. So i decided to solve my video driver issue first. llvmpipe, gosh took me some time to get rid of it.

kaiju8@kaiju8 ~>  doas emerge --depclean x11-drivers/xf86-video-intel
kaiju8@kaiju8 ~> cat /etc/portage/package.use/mesa 
media-libs/mesa iris vulkan egl gbm dri3 zink
kaiju8@kaiju8 ~> cat /etc/portage/package.use/xorg-server 
x11-base/xorg-server glamor udev

From this, the zink vulkan egl dri3 and iris I added. Also had to make sure glamor was getting used. It is probably not-required, unless you had the minimal flag set. Anyway, these are mostly system setup to move away from the xf86-video-intel , so I did the rest of necessary steps.

kaiju8@kaiju8 ~>  glxinfo| grep -i 'opengl'

OpenGL vendor string: Intel
OpenGL renderer string: llvmpipe

was the first result. After installing these and override the x org input conf for intel to looks like this:

Section "Device"
   Identifier  "Intel Graphics"
   Driver      "modesetting"
   Option      "AccelMethod" "glamor"
   Option      "DRI"         "3"
   Option      "TearFree"    "true"
EndSection

The AccelMethod 'glamor' did the trick. Upon reboot, I could see my glxinfo doin:

kaiju8@kaiju8 ~>   glxinfo| grep -i 'opengl'
OpenGL vendor string: Intel
OpenGL renderer string: Mesa Intel(R) UHD Graphics 620 (KBL GT2)

with that, when I ran the wezterm from cli, the above mesa errors went away.

As a finishing step, I reverted my wezterm.lua, to load the fonts, and them, and use "WebGpu" frontend. The initial load took some time, which I spent freaking out. But now It works like butter

STAT                                    current p50  p75  p95 
Key(glyph_cache.glyph_cache.hit.rate)   0       125  189  189 
Key(glyph_cache.glyph_cache.miss.rate)  0       41   41   41  
Key(gui.paint.impl.rate)                0       54   55   55  
Key(line_quad_cache.hit.rate)           0       3471 3519 3519
Key(line_quad_cache.miss.rate)          0       64   64   64  
Key(line_state_cache.hit.rate)          0       3407 3519 3519
Key(line_to_ele_shape_cache.hit.rate)   0       55   90   113 
Key(line_to_ele_shape_cache.miss.rate)  0       1    4    4   
Key(mux.pane_output_event.rate)         0       2    5    5   
Key(read_from_pane_pty.bytes.rate)      0       250  399  399 
Key(send_actions_to_mux.rate)           0       2    5    5   
Key(shape_cache.hit.rate)               0       327  331  331 
Key(shape_cache.miss.rate)              0       1    24   24  
Key(window.atlas.allocate.success.rate) 0       1    43   43  

STAT                                             p50      p75      p95     
Key(cached_cluster_shape)                        1.80µs   2.19µs   5.54µs  
Key(executor.spawn_delay)                        75.26µs  128.51µs 2.23ms  
Key(gui.paint.impl)                              1.97ms   2.13ms   4.00ms  
Key(paint_pane.lines)                            327.68µs 364.54µs 413.70µs
Key(quad.map)                                    7.62µs   8.13µs   8.96µs  
Key(quad_buffer_apply)                           94.00ns  116.00ns 2.59µs  
Key(render_screen_line)                          44.03µs  122.88µs 140.29µs
Key(send_actions_to_mux.perform_actions.latency) 40.70µs  83.97µs  86.02µs 
Key(shape.harfbuzz)                              13.50µs  20.10µs  167.94µs
Key(window.atlas.allocate.latency)               4.67µs   6.72µs   35.33µs 

I can see significant difference in the STATS p95 after the changes