bug: very high GPU usage for the spectrogram visual

[edwloef]

Before filing

• I searched existing issues for a duplicate.
• I can reproduce this.

OpenMeters version

d424393

Environment

• Distribution: Arch Linux
• Session: Wayland
• Compositor: Sway
• PipeWire version: 1.6.8
• GPU/driver: Intel® Iris® Xe Graphics
• Install method: AUR

Steps to reproduce

1. enable the Spectrogram visual

Expected behavior

not almost 100% GPU utilization

Actual behavior

almost 100% GPU utilization

Logs or crash output

Additional context

Removing the spectrogram visual lowers GPU utilization to around 10%

[httpsworldview]

I cannot seem to reproduce this on my machine, and no recent or historical changes to the spectrogram would result in such a regression. Has anything about your system changed recently?

[edwloef]

Nothing that I'm aware of. The GPU utilization also seems to vary with the width of the spectrogram, so that's at least another datapoint pointing at it being the culprit. Here's a video, in case it helps. The difference is a bit smaller probably because OBS is running, but it's still very obvious:

2026-09-09.16-32-36.mp4

[httpsworldview]

I'll look into this. Was this always an issue, or did it begin with recent commits? Did any other driver updates occur around the same time? If it's not too much to ask, and if you are able, can you reproduce this on another machine?

Also, it is expected for GPU usage to increase with the width of the spectrogram, especially with reassignment enabled.

[httpsworldview]

If you wouldn't mind, I think it might be useful to know the exact CPU you have as well.

[edwloef]

Was this always an issue, or did it begin with recent commits?

If I had to guess, it's always been an issue, and I just noticed it now because the default frame-rate changed.

Did any other driver updates occur around the same time?

None that I'm aware of, no.

If it's not too much to ask, and if you are able, can you reproduce this on another machine?

I don't currently have another machine available to me to test, sorry :(

If you wouldn't mind, I think it might be useful to know the exact CPU you have as well.

Intel® Core™ i7-13700H Processor

[httpsworldview]

No problem, thank you for the info. I ran the latest commit on a significantly worse Intel ThinkPad I have (i5-8350U, UHD 620 graphics), and even then I did not see over 40% utilization on the iGPU. Paired with all of the testing on my main machine, I'm still not sure what the cause is, but I'm relatively certain that it has something to do with your particular CPU/iGPU, even though many rendering optimizations are still possible.

Sorry, I can't reproduce this, and I'm still stumped. I'll leave this issue open for now as I continue to investigate.

[edwloef]

Do you know of any GPU profilers I could measure with, that could help you diagnose the issue?

[edwloef]

I tried with RenderDoc, but I'm getting this panic on startup:

thread 'main' (39584) panicked at /home/edwin/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/iced_exwlshell-0.20.0/src/multi_window.rs:367:60:
Cannot create compositor: GraphicsAdapterNotFound { backend: "wgpu", reason: RequestFailed("the surface is not compatible") }

[httpsworldview]

Do you know of any GPU profilers I could measure with, that could help you diagnose the issue?

RenderDoc, Mesa's u_trace, however profiling only tells me where time goes, not necessarily why your machine is behaving differently.

Some more diagnostic information might help if it's not too much to ask:

pacman -Q mesa vulkan-intel vulkan-icd-loader
lspci -nnk | grep -A3 -E "VGA|3D|Display"
vulkaninfo --summary

(vulkaninfo comes from vulkan-tools if it isn't installed).

[edwloef]

pacman -Q mesa vulkan-intel vulkan-icd-loader

mesa 1:26.2.2-1
vulkan-intel 1:26.2.2-1
vulkan-icd-loader 1.4.357.0-1

lspci -nnk | grep -A3 -E "VGA|3D|Display"

00:02.0 VGA compatible controller [0300]: Intel Corporation Raptor Lake-P [Iris Xe Graphics] [8086:a7a0] (rev 04)
	Subsystem: Lenovo Device [17aa:3ca1]
	Kernel driver in use: i915
	Kernel modules: i915, xe
--
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation AD107M [GeForce RTX 4050 Max-Q / Mobile] [10de:28e1] (rev a1)
	Subsystem: Lenovo Device [17aa:3ca1]
	Kernel driver in use: nvidia
	Kernel modules: nouveau, nvidia_drm, nvidia

vulkaninfo --summary

==========
VULKANINFO
==========

Vulkan Instance Version: 1.4.357


Instance Extensions: count = 27
-------------------------------
VK_EXT_acquire_drm_display             : extension revision 1
VK_EXT_acquire_xlib_display            : extension revision 1
VK_EXT_debug_report                    : extension revision 10
VK_EXT_debug_utils                     : extension revision 2
VK_EXT_direct_mode_display             : extension revision 1
VK_EXT_display_surface_counter         : extension revision 1
VK_EXT_headless_surface                : extension revision 1
VK_EXT_layer_settings                  : extension revision 2
VK_EXT_surface_maintenance1            : extension revision 1
VK_EXT_swapchain_colorspace            : extension revision 5
VK_KHR_device_group_creation           : extension revision 1
VK_KHR_display                         : extension revision 23
VK_KHR_external_fence_capabilities     : extension revision 1
VK_KHR_external_memory_capabilities    : extension revision 1
VK_KHR_external_semaphore_capabilities : extension revision 1
VK_KHR_get_display_properties2         : extension revision 1
VK_KHR_get_physical_device_properties2 : extension revision 2
VK_KHR_get_surface_capabilities2       : extension revision 1
VK_KHR_portability_enumeration         : extension revision 1
VK_KHR_surface                         : extension revision 25
VK_KHR_surface_maintenance1            : extension revision 1
VK_KHR_surface_protected_capabilities  : extension revision 1
VK_KHR_wayland_surface                 : extension revision 6
VK_KHR_xcb_surface                     : extension revision 6
VK_KHR_xlib_surface                    : extension revision 6
VK_LUNARG_direct_driver_loading        : extension revision 1
VK_NV_display_stereo                   : extension revision 1

Instance Layers: count = 9
--------------------------
VK_LAYER_MESA_anti_lag            Open-source implementation of the VK_AMD_anti_lag extension. 1.4.303  version 1
VK_LAYER_MESA_device_select       Linux device selection layer                                 1.4.303  version 1
VK_LAYER_NV_optimus               NVIDIA Optimus layer                                         1.4.341  version 1
VK_LAYER_NV_present               NVIDIA Presentation Layer                                    1.4.341  version 1
VK_LAYER_RENDERDOC_Capture        Debugging capture layer for RenderDoc                        1.4.324  version 45
VK_LAYER_VALVE_steam_fossilize_32 Steam Pipeline Caching Layer                                 1.3.207  version 1
VK_LAYER_VALVE_steam_fossilize_64 Steam Pipeline Caching Layer                                 1.3.207  version 1
VK_LAYER_VALVE_steam_overlay_32   Steam Overlay Layer                                          1.3.207  version 1
VK_LAYER_VALVE_steam_overlay_64   Steam Overlay Layer                                          1.3.207  version 1

Devices:
========
GPU0:
	apiVersion         = 1.4.354
	driverVersion      = 26.2.2
	vendorID           = 0x8086
	deviceID           = 0xa7a0
	deviceType         = PHYSICAL_DEVICE_TYPE_INTEGRATED_GPU
	deviceName         = Intel(R) Iris(R) Xe Graphics (RPL-P)
	driverID           = DRIVER_ID_INTEL_OPEN_SOURCE_MESA
	driverName         = Intel open-source Mesa driver
	driverInfo         = Mesa 26.2.2-arch1.1
	conformanceVersion = 1.4.0.0
	deviceUUID         = 8680a0a7-0400-0000-0002-000000000000
	driverUUID         = af44288b-59dd-a79f-c93d-b6e4e1ea7f6f
GPU1:
	apiVersion         = 1.4.341
	driverVersion      = 610.57.4.0
	vendorID           = 0x10de
	deviceID           = 0x28e1
	deviceType         = PHYSICAL_DEVICE_TYPE_DISCRETE_GPU
	deviceName         = NVIDIA GeForce RTX 4050 Laptop GPU
	driverID           = DRIVER_ID_NVIDIA_PROPRIETARY
	driverName         = NVIDIA
	driverInfo         = 610.57.04
	conformanceVersion = 1.4.3.3
	deviceUUID         = e5d9e92a-030f-e1d3-c52c-8f933e534f81
	driverUUID         = 9992f558-9329-580d-a9f3-a38ee24bc64d

[httpsworldview]

Thanks for the diagnostics and for working through this with me. I still haven't been able to reproduce anything on my available hardware, and the cause remains unsolved.

I don't have the capacity to investigate this further right now, so I'm going to leave it be. I'll leave this open for additional reports or contributions. Thanks, and sorry again.

[edwloef]

Oh, for what it's worth I can also kinda reproduce this using my dgpu (the nvidia one shown up top), where usage without the spectrogram is about 25% and 2W power draw, and with is about 40% and 10W power draw, both according to nvidia-smi. So it's probably not specific to the gpu itself.