Any linux wizards know why when my sound sources go to background and CPU is under heavy load the audio crackles?
apps tested: minecraft, vlc(flatpak), spotify(flatpak), other fltapaks
crackles on both bluetooth and minijack headphones,
disabling microphone, easyeffects, gpu screen recorder ( gsr-default_output) didn’t help
I use blender to put the load on CPU but it also happens when compiling or gaming
I have increased stuff in cat /etc/pipewire/pipewire.conf
[…]
## Properties for the DSP configuration.
default.clock.rate = 192000
#default.clock.allowed-rates = [ 48000 ]
default.clock.quantum = 1024
default.clock.min-quantum = 32
default.clock.max-quantum = 4096
[…]
pw-top -b
S ID QUANT RATE WAIT BUSY W/Q B/Q ERR FORMAT NAME
S 29 0 0 --- --- --- --- 0 Dummy-Driver
S 30 0 0 --- --- --- --- 0 Freewheel-Driver
S 45 0 0 --- --- --- --- 0 Midi-Bridge
S 48 0 0 --- --- --- --- 0 bluez_midi.server
R 52 2048 192000 10,6ms 69,7us 0,99 0,01 453 S32LE 2 48000 alsa_output.pci-0000_06_00.6.analog-stereo
R 213 900 48000 229,0us 69,1us 0,02 0,01 0 F32LE 2 48000 + Firefox
R 219 0 0 13,0us 41,1us 0,00 0,00 0 F32P 2 192000 + easyeffects_sink
R 217 0 0 +++ 17,0us +++ 0,00 428 + ee_soe_output_level
R 174 0 0 9,3ms 34,3us 0,88 0,00 5416 + ee_soe_spectrum
R 206 512 48000 300,5us 54,3us 0,03 0,01 0 F32LE 2 48000 + java
R 186 900 48000 359,5us 56,2us 0,03 0,01 0 F32LE 2 48000 + Firefox
R 242 900 48000 417,2us 52,4us 0,04 0,00 0 F32LE 2 48000 + Firefox
R 129 960 48000 152,1us 74,5us 0,01 0,01 0 S16LE 2 48000 + gsr-default_output
R 116 1920 48000 472,4us 62,5us 0,04 0,01 0 F32LE 2 48000 + VLC media player (LibVLC 3.0.23)
I 53 4096 192000 8,9us 3,3us 0,00 0,00 109 S32LE 2 192000 alsa_input.pci-0000_06_00.6.analog-stereo
S 68 0 0 --- --- --- --- 0 v4l2_input.pci-0000_06_00.3-usb-0_3_1.0
I 191 0 0 0,0us 0,0us ??? ??? 0 F32LE 2 48000 Firefox
I 216 0 0 0,0us 0,0us ??? ??? 0 F32LE 2 48000 Firefox
I 220 0 0 0,0us 0,0us ??? ??? 0 F32LE 2 48000 Firefox
S 244 0 0 --- --- --- --- 0 Blender
I 205 0 0 0,0us 0,0us ??? ??? 0 F32LE 2 44100 spotify
R 249 2048 192000 10,7ms 35,5us 1,00 0,00 1339 S16LE 1 48000 alsa_input.usb-145f_Trust_GXT_242_Microphone-00.mono-fallback
R 120 0 0 12,2us 13,5us 0,00 0,00 7 F32P 2 192000 + easyeffects_source
R 145 0 0 6,2us 8,2us 0,00 0,00 90 + ee_sie_output_level
R 230 0 0 5,7us 7,6us 0,00 0,00 118 + ee_sie_spectrum
R 144 960 48000 18,9us 49,7us 0,00 0,00 0 S16LE 2 48000 + gsr-default_input
R 257 0 0 122,2us +++ 0,01 +++ 1101 + ee_sie_rnnoise
R 106 0 0 44,8us 139,8us 0,00 0,01 236 + ee_sie_stereo_tools
R 84 0 0 --- 8,6us --- 0,00 235 + ee_sie_crossfeed
R 158 0 0 5,3us 7,8us 0,00 0,00 30 + ee_sie_reverb
R 171 0 0 5,2us 8,9us 0,00 0,00 4 + ee_sie_equalizer
S 172 0 0 --- --- --- --- 0 plasmashell
S 119 0 0 --- --- --- --- 0 plasmashell
S 233 0 0 --- --- --- --- 0 ee_test_signals
S 193 0 0 --- --- --- --- 0 plasmashell
I 175 0 0 0,0us 0,0us ??? ??? 0 F32LE 2 48000 plasmashell
I know to little to dig into the scheduler stuff. systemctl status rtkit-daemon prints about pipewire sucess at priority 20.
I am on KDE/linux (bazzite based on fedora atomic44)
--------------
OS: Bazzite x86_64
Host: 82JU (Legion 5 15ACH6H)
Kernel: Linux 7.1.3-ogc3.4.fc44.x86_64
Uptime: 4 hours, 46 mins
Packages: 2 (appimage), 4 (brew), 1 (brew-cask), 173 (flatpak), 3014 (rpm)
Shell: bash 5.3.9
Display (BOE08E8): 1920x1080 in 16", 120 Hz [Built-in]
DE: KDE Plasma 6.7.2
WM: KWin (Wayland)
WM Theme: leaf-dark-color
Theme: Fusion (LeafDark) [Qt], Vapor [GTK2/3]
Icons: breeze-dark [Qt], breeze-dark [GTK3/4]
Font: Noto Sans (10pt) [Qt], Noto Sans (10pt) [GTK3/4]
Cursor: Teto (30px)
Terminal: konsole 26.4.3
CPU: AMD Ryzen 5 5600H (12) @ 4.28 GHz
GPU 1: NVIDIA GeForce RTX 3060 Mobile / Max-Q [Discrete]
GPU 2: AMD Radeon Vega Series / Radeon Vega Mobile Series [Integrated]
Memory: 12.05 GiB / 13.49 GiB (89%)
Swap: 16.62 GiB / 35.59 GiB (47%)
Disk (/): 49.00 MiB / 49.00 MiB (100%) - overlay [Read-only]
Disk (/etc): 845.89 GiB / 929.93 GiB (91%) - btrfs
Local IP (tun0): 10.96.0.42/16
Battery (L20M4PC0): 100% [AC Connected]
Locale: pl_PL.UTF-8
I have ruled out the RAM issue by running as simplified test as possible: spotify + stress-ng and easy effects not running
free -h total used free shared buff/cache available Mem: 13Gi 7,8Gi 851Mi 166Mi 5,9Gi 5,7Gi Swap: 35Gi 2,3Gi 33Giiostat Linux 7.1.3-ogc3.4.fc44.x86_64 (bazzite) 17.07.2026 _x86_64_ (12 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 10,04 0,01 2,64 0,11 0,00 87,20 Device tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd nvme0n1 0,03 0,67 0,00 0,00 11939 0 0 nvme1n1 108,97 1720,07 2211,60 2309,40 30620304 39370413 41111372 zram0 145,99 105,04 478,97 0,00 1869980 8526568 0I have started to dig more into the
perf,trace-cmdandcyclictestand finally managed to run all of the in the same time to capture the same high delay event. If the arch forum is correct then pipewire usesdata-loop.0process for realtime processing. It got SCHED_RR, so it seems correct as according to man pages it would preempt the SCHED_OTHER that stress-ng runs in.Interesting thing I (and a council of clankers) noticed in trace_cpu_4.txt is that the interrupt didn’t fire at specified time, and when it did, scheduler immediately preempted stress-ng to run the cyclictest as it’s SHED_FIFO.
My current theory is some sort interrupt problem
trace-cmd report > trace.txtsed -n '2682652,2684299p' trace.txt > trace_extract.txtcat trace_extract.txt | grep -i "\[004\]" > trace_cpu_4.txtlogs:
ps -eo pid,class,rtprio,ni,pri,comm -L | grep -i 'rr\|ff\|dln' 19 FF 99 - 139 migration/0 21 FF 50 - 90 idle_inject/0 24 FF 50 - 90 idle_inject/2 25 FF 99 - 139 migration/2 30 FF 50 - 90 idle_inject/4 31 FF 99 - 139 migration/4 36 FF 50 - 90 idle_inject/6 37 FF 99 - 139 migration/6 42 FF 50 - 90 idle_inject/8 43 FF 99 - 139 migration/8 48 FF 50 - 90 idle_inject/10 49 FF 99 - 139 migration/10 54 FF 50 - 90 idle_inject/1 55 FF 99 - 139 migration/1 60 FF 50 - 90 idle_inject/3 61 FF 99 - 139 migration/3 66 FF 50 - 90 idle_inject/5 67 FF 99 - 139 migration/5 72 FF 50 - 90 idle_inject/7 73 FF 99 - 139 migration/7 78 FF 50 - 90 idle_inject/9 79 FF 99 - 139 migration/9 84 FF 50 - 90 idle_inject/11 85 FF 99 - 139 migration/11 104 FF 50 - 90 irq/9-acpi 108 TS - -20 39 kworker/R-ata_sff 112 FF 50 - 90 watchdogd 115 FF 50 - 90 irq/25-AMD-Vi0-Evt 116 FF 50 - 90 irq/26-AMD-Vi0-PPR 117 FF 50 - 90 irq/27-AMD-Vi0-GA 428 TS - -20 39 kworker/R-amdgpu_dm_hpd_rx_offload_wq 430 FF 50 - 90 card1-crtc0 431 FF 50 - 90 card1-crtc1 432 FF 50 - 90 card1-crtc2 433 FF 50 - 90 card1-crtc3 461 TS - 0 19 nvidia-modeset/deferred_close_kthread_q 462 FF 50 - 90 irq/62-nvidia 475 TS - 0 19 UVM deferred release queue 624 FF 50 - 90 irq/63-ELAN06FA:00 770 FF 1 - 41 psimon 842 FF 1 - 41 psimon 1255 FF 50 - 90 irq/96-rtw89_pci 1513 RR 99 - 139 rtkit-daemon 1589 FF 1 - 41 psimon 3098 RR 1 - 41 kwin_wayland 3098 RR 1 - 41 eDP-1 3098 RR 1 - 41 libinput-connec 3114 RR 20 - 60 data-loop.0 3115 RR 20 - 60 data-loop.0 3316 RR 20 - 60 data-loop.0 3316 RR 20 - 60 data-loop.0 3316 TS - 0 19 bazaarrunner 3316 TS - 0 19 krunner_charrun 3327 RR 20 - 60 data-loop.0 6596 TS - 0 19 WRRende~ckend#1 6596 TS - 0 19 WRRende~kend#19 37282 FF 1 - 41 psimon 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictest 37326 FF 80 - 120 cyclictestsudo cyclictest --mlockall --smp --priority=80 --interval=200 --breaktrace=800 # /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 11.16 5.94 3.72 19/2368 37630 T: 0 (37327) P:80 I:200 C: 268947 Min: 8 Act: 13 Avg: 13 Max: 462 T: 1 (37329) P:80 I:700 C: 76837 Min: 8 Act: 15 Avg: 13 Max: 78 T: 2 (37330) P:80 I:1200 C: 44819 Min: 9 Act: 15 Avg: 14 Max: 49 T: 3 (37331) P:80 I:1700 C: 31635 Min: 8 Act: 14 Avg: 14 Max: 153 T: 4 (37332) P:80 I:2200 C: 24443 Min: 9 Act: 15 Avg: 14 Max: 106 T: 5 (37333) P:80 I:2700 C: 19915 Min: 9 Act: 14 Avg: 14 Max: 132 T: 6 (37334) P:80 I:3200 C: 16802 Min: 9 Act: 19 Avg: 14 Max: 766 T: 7 (37335) P:80 I:3700 C: 14531 Min: 9 Act: 15 Avg: 14 Max: 179 T: 8 (37336) P:80 I:4200 C: 12800 Min: 8 Act: 21 Avg: 13 Max: 37 T: 9 (37337) P:80 I:4700 C: 11437 Min: 9 Act: 19 Avg: 14 Max: 264 T:10 (37338) P:80 I:5200 C: 10337 Min: 9 Act: 17 Avg: 14 Max: 73 T:11 (37339) P:80 I:5700 C: 9430 Min: 9 Act: 18 Avg: 14 Max: 83 # Thread Ids: 37327 37329 37330 37331 37332 37333 37334 37335 37336 37337 37338 37339 # Break thread: 37332 # Break value: 2488sudo perf sched timehist > perf_timehist.txtawk '$1 >= 9980.792239 && $1 <= 9980.797096' perf_timehist.txt > perf_extract.txthttps://pastebin.com/iuB98bXgsudo perf sched latency > perf_latency.txthttps://pastebin.com/JP0PfrSU