linux-image-2.6.27-10 and newer causes audio skips under CPU load

[Andrew Conkling]

Binary package hint: linux-image-2.6.27-10-generic

Since upgrading to linux-image-2.6.27-10-generic, I get a lot of audio skips while playing music when my computer is under load. Without changing the rest of the configuration, booting into linux-image-2.6.27-8-generic makes the skips go away.

To reproduce:
1. Play music (I tested in Rhythmbox and Banshee).
2. While playing, move a window across the screen for more than a second or two.
3. Also, opening an application (e.g. Firefox) or loading a Javascript-heavy browser page (e.g. Gmail, Facebook) will trigger this as well. It corresponds to CPU spikes in System Monitor.

Kernel bugs are not really new to me, so let me know what else I can do to test/debug this.

[Andrew Conkling (andrewski)]

Got a request (http://identi.ca/notice/1330650) to find out some ALSA info (a really neat script!). Attached is the info for 2.6.27-8-generic. I'll get the info for 2.6.27-10-generic and post that also.

[Andrew Conkling (andrewski)]

Here's the info for 2.6.27-10-generic. Just to be confident in my report, I fired up Banshee and it's skipping again.

[Daniel T Chen (crimsun)]

This issue is unlikely to be sound driver-related: there are no emu10k1-related changes between -8 and -10. If you bypass pulseaudio altogether (and just use alsa) for GSt audiosink, does banshee still exhibit the erratic behaviour?

Please attach the contents of /etc/pulse/daemon.conf.

[Andrew Conkling (andrewski)]

No, it does not seem to be resolved with ALSA, though it *may* be skipping less. I assume you mean System | Preferences | Sound, and changing Music and Movies/Sound playback to ALSA? It was on Autodetect before, for what that's worth.

[Andrew Conkling (andrewski)]

Same thing is happening on Jaunty, with 2.6.28-6, but also with 2.6.27-8-generic (which was fine on Intrepid). Attaching ALSA info again. So it doesn't seem to be kernel- or driver-related; what else could be causing this? How else can I debug the issue?

[Andrew Conkling (andrewski)]

I've found that this only happens when X is running, with either the nv or the nvidia driver; aplay/gst-launch from the terminal do not cause skipping when X is not running but do when it is.

Does that explain anything or otherwise help narrow down what could be causing this?

[Fabian A. Scherschel (fabsh)]

I can confirm this on current Jaunty (patched today) with 2.6.28-8 and nvidia driver 180. Seems to happen mostly when scrolling pages in Firefox at about 25% CPU load on one core, under 10% load on the other. I am playing audio from Banshee (newest version from the Jaunty repos).

[Brad Figg (brad-figg)]

This bug was filed against a series that is no longer supported and so is being marked as Won't Fix. If this issue still exists in a supported series, please file a new bug.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.