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
Hmm.
Those are very high max delay numbers. Like, a hundred plus milliseconds before a process that wanted to run code could run. I’d be expecting single digits at most. You’d expect the breakups — that’s not something that you can reasonably deal with by just jacking up buffer size.
That’s also not something I’d expect from normal CPU load, not unless another process has elevated priority or you were running extraordinarily high numbers of threads. Yeah, could be kernel code blocking, but those are extreme numbers. Maybe if the system is severely paging, like, out of memory.
Do you mention memory usage anywhere?
goes looking through stuff
Oh. Yeah. You did and I skimmed right past it. Okay, that’d maybe do it. You’re deep in swap. Like:
That’d definitely create at least that much delay on rotational disks. I haven’t ever tried putting my system under a lot of swap load on SSDs, but I could believe it. And someone else mentioned it too, which I ignored.
You have swap triple your physical memory and you’re using using all your memory and using swap equal to time-and-a-half your physical memory.
I’d normally use maybe 100% of my memory in swap and generally try to avoid hitting it. I’m not saying that you couldn’t get away with that much in swap, but if you do, most of it would have to be pretty inactive stuff.
Try killing off some of the heavy memory consumers. You can run
topand hit shift-M and it’ll sort by memory usage, help identify the heavy users. If the problem goes away, well, that’s probably it.If you run
iostat, you should see something like this:If your %iowait number is up there, your system is probably just spending all that time paging like crazy.
So, couple things you can do.
Obviously, not running some of the heavy memory consumers would help, see what you can pare down. Uh. You can probably save a bit by using a lighter desktop environment or something, but I can already tell you that if you’re using that much, most of it’s gonna be whatever software you’re running, not the base system.
If that laptop can take more memory and you can stick bigger DIMMs in — and it looks, from a quick skim, like it doesn’t have soldered memory — then it looks like that thing can handle up to 64GB in SODIMMs, though I would confirm that before you go buying memory.
If you’re determined to try to run your existing apps with that hardware configuration…well, it’s technically possible to use compressed swap that’ll reduce the amount of I/O your system is doing (though use more CPU time). Linux has zram and zswap. zswap’s the easier to enable. I haven’t used it myself, but looks like if you want to enable it temporarily, for the current boot, as root, do
# echo 1 >/sys/module/zswap/parameters/enabled. If it becomes tolerable after that — the max delay numbers should drop down to single digits — you can make it persistent by addingzswap.enabled=1to the kernel command line at boot (I’d have to look up how to do that in Bazzite; on Debian, it’d be settingGRUB_CMDLINE_LINUX_DEFAULT="zswap.enabled"in /etc/default/grub and then running$ sudo update-grub).You can maybe do something exotic like using cgroups to try to force a given process (like, not your memory player or any processes involved in playing audio) from using a lot of real memory so that it is the one that takes more of the brunt of paging, but I haven’t done that myself.
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