kernel-packages team mailing list archive

[Vassil Panayotov <vd.panayotov@xxxxxxxxx>]

@Alex Deucher: Yes, the modern operating systems and hardware are complex beasts and I surely understand that some bugs may be hard to track down. The point is however that there wasn't a systematic effort to resolve this particular issue except for some "there is a random problem X described in ticket Y, which may be the reason for your troubles too, so why don't you try the solution proposed there". By the way I tried the change proposed by Michel Dänzer in https://bugs.freedesktop.org/show_bug.cgi?id=38694 , but unfortunately it doesn't seem to help either.
I am clueless about the kernel internals, but the manifestations of this bug seem to be consistent with the hypothesis that there is something wrong with the "radeon" driver. It seems like something locks the system for long periods of time and the other time sensitive modules "freak out". On my laptop the problem became even more pronounced when I swapped the "1440x900" LCD panel with a "1600x1200" one.

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https://bugs.launchpad.net/bugs/571770

Title:
  Thread [hd-audio0] consuming excessive amounts of CPU, audio crackling

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: linux-image-2.6.32-22-generic

  Sometimes during audio playback, a kernel thread named "[hd-audio0]"
  will consume excessive amounts of CPU and cause  audio crackling. It
  seems to be more easily triggered when displaying video in fullscreen
  (or Rhythmbox visualizations) or dragging windows around while playing
  music, somehow relating it graphics operations (running default radeon
  driver with KMS and Compiz).

  This all started after moving from Ubuntu Karmic to Lucid (never had
  this problem before).

  Setting package to kernel, since it's probably alsa snd_hda_intel
  kernel module which is to blame.

  Ubuntu 10.04 x86, Intel Core Duo 2GHz, 3GB RAM, ATI X1400 Radeon Mobility graphics.
  Audio chip: Analog Devices AD1981 [HDA]

  WORKAROUND: Disabling radeon KMS makes all the audio crackling go
  away.

  Attaching:
  * Screenshot of top running over Rhythmbox w/fullscreen visualizations, showing [hd-audio0] consuming more CPU than everything else at the time (audio crackles).
  * Output of "lspci -vvnn"
  * Output of "dmesg"
  * Contents of /proc/interrupts
  * ALSA info, as provided by the alsa-info.sh script.

  Related to this: https://bugzilla.kernel.org/show_bug.cgi?id=14935 ???

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