Some more info. On my new laptop that also has a VIA sound chipset I managed to greatly leverage the problem by installing the low-latency Ubuntu kernel. I have Ubuntu MATE 14.04 on it so it was effortless. Unfortunately, for (presumably) performance reasons it doesn't have CONFIG_SND_PCM_XRUN_DEBUG enabled so I can't see if it also misses interrupts. However, on the default stock kernel which has this option it misses interrupts indeed. I tried various position_fix and enable_msi values and nothing helped. I had underruns in the log while doing usual things like opening sites, now on the low-latency kernel it's all good even on PA's timer-based scheduling.
I can only guess but it could be because the CPU has only two cores and sometimes it can't schedule an interrupt in time. The low-latency kernel has 1000 Hz timer compared to 250 Hz in the default one. It also has various NO_HZ_* options enabled. I'll try two options on Monday with my own kernel for Debian: one would be using the BFS scheduler and another one will feature CONFIG_NO_HZ_FULL_ALL and alike options which are disabled when BFS is used. I'll check if either of them will help with the missed interrupts. The problem as I see it is that my work PC and this laptop isn't powerful enough to server IRQs in time. They both have VIA sound although a bit different models and 2 core CPUs. My home PC has 4 cores that are also more powerful. I tried to output some sound via PA to its Realtek ALC889 card and enabled xrun_debug. There were no messages about lost interrupts and I'm using the same kernel that's used on the work PC. So the different behavior is either because of different codecs/chipsets or CPUs. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to pulseaudio in Ubuntu. https://bugs.launchpad.net/bugs/996906 Title: periodic audio skips with Intel HDA Status in PulseAudio sound server: Confirmed Status in pulseaudio package in Ubuntu: Confirmed Bug description: When running PulseAudio, if I'm playing music via any source (Exaile, Totem, Flash in Firefox or Chromium, VLC, etc.) every few minutes the audio will skip once or twice. top doesn't show any process eating CPU any more when it happens. dmesg doesn't show anything. Nothing else seems to be affected. It doesn't seem to happen regularly. I just installed Ubuntu 12.04 from scratch (with pulseaudio 1:1.1-0ubuntu15), but the same thing happened in 10.04 on the same hardware. Uninstalling the PulseAudio packages and going back to ALSA gives me no issues whatsoever, which is how I know the issue is with PulseAudio. I'm using my onboard audio device: $ lspci | grep Audio 00:14.2 Audio device: Advanced Micro Devices [AMD] nee ATI SBx00 Azalia (Intel HDA) Following mailing list instructions, pulseaudio -vvvv --log-time shows during a skip: ( 684.030| 5.000) I: [alsa-sink] alsa-sink.c: Underrun! ( 684.030| 0.000) I: [alsa-sink] alsa-sink.c: Increasing minimal latency to 26.00 ms ( 684.030| 0.000) D: [alsa-sink] alsa-sink.c: Latency set to 26.00ms ( 684.030| 0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=60952 ( 684.030| 0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15944 ( 684.030| 0.000) D: [alsa-sink] alsa-sink.c: Latency set to 26.00ms ( 684.030| 0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=60952 ( 684.030| 0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15944 ( 684.031| 0.000) D: [alsa-sink] protocol-native.c: Underrun on 'ALSA Playback', 0 bytes in queue. ( 684.036| 0.004) D: [alsa-sink] protocol-native.c: Requesting rewind due to end of underrun. ( 684.036| 0.000) D: [alsa-sink] alsa-sink.c: Requested to rewind 10940 bytes. ( 684.036| 0.000) D: [alsa-sink] alsa-sink.c: Limited to 3320 bytes. ( 684.036| 0.000) D: [alsa-sink] alsa-sink.c: before: 830 ( 684.036| 0.000) D: [alsa-sink] alsa-sink.c: after: 830 ( 684.036| 0.000) D: [alsa-sink] alsa-sink.c: Rewound 3320 bytes. ( 684.036| 0.000) D: [alsa-sink] sink.c: Processing rewind... ( 684.036| 0.000) D: [alsa-sink] sink.c: latency = 1337 ( 684.036| 0.000) D: [alsa-sink] sink-input.c: Have to rewind 3320 bytes on render memblockq. ( 684.036| 0.000) D: [alsa-sink] source.c: Processing rewind... ( 696.234| 12.197) I: [alsa-sink] alsa-sink.c: Underrun! ( 696.234| 0.000) I: [alsa-sink] alsa-sink.c: Increasing wakeup watermark to 15.99 ms ( 702.033| 5.799) I: [alsa-sink] alsa-sink.c: Underrun! ( 702.033| 0.000) I: [alsa-sink] alsa-sink.c: Increasing minimal latency to 36.00 ms ( 702.033| 0.000) D: [alsa-sink] alsa-sink.c: Latency set to 36.00ms ( 702.033| 0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=59188 ( 702.033| 0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15680 ( 702.033| 0.000) D: [alsa-sink] alsa-sink.c: Latency set to 36.00ms ( 702.034| 0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=59188 ( 702.034| 0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15680 ( 702.034| 0.000) D: [alsa-sink] protocol-native.c: Underrun on 'ALSA Playback', 0 bytes in queue. ...and it goes on. The "Underrun!" messages alone happened a few times before, but it didn't skip. I'd like to use PulseAudio, but it's pretty annoying having audio skip all the time. ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: pulseaudio 1:1.1-0ubuntu15 ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14 Uname: Linux 3.2.0-24-generic x86_64 NonfreeKernelModules: nvidia AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24. ApportVersion: 2.0.1-0ubuntu7 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: toxite 2136 F.... pulseaudio /dev/snd/pcmC0D0p: toxite 2136 F...m pulseaudio Card0.Amixer.info: Card hw:0 'SB'/'HDA ATI SB at 0xfe024000 irq 16' Mixer name : 'Realtek ALC889' Components : 'HDA:10ec0889,1458a102,00100004' Controls : 48 Simple ctrls : 22 Date: Tue May 8 21:45:17 2012 InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425) ProcEnviron: TERM=xterm PATH=(custom, user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: pulseaudio UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/03/2009 dmi.bios.vendor: Award Software International, Inc. dmi.bios.version: F2 dmi.board.name: GA-790FXTA-UD5 dmi.board.vendor: Gigabyte Technology Co., Ltd. dmi.board.version: x.x dmi.chassis.type: 3 dmi.chassis.vendor: Gigabyte Technology Co., Ltd. dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrF2:bd12/03/2009:svnGigabyteTechnologyCo.,Ltd.:pnGA-790FXTA-UD5:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnGA-790FXTA-UD5:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr: dmi.product.name: GA-790FXTA-UD5 dmi.sys.vendor: Gigabyte Technology Co., Ltd. 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