Event-hungry kernel blocks system

[private_lock]

Binary package hint: kernel-image-2.6.24-19-generic-di

Hello!

My whole system tends to lockup, whenever I'm not typing or moving the mouse. Everything returns to normal, once I provide a constant stream of input.

This affects *all* applications. Symptoms include:
- cursors stop blinking *everywhere* in KDE (kwrite, kate, this textbox in firefox, ...)
- the clock in the tray is stuck
- if a screensaver is active, it doesn't repaint
- the diagrams in ksysguard don't update anymore
- animated gifs in Firefox freeze
- tooltips for the desktop previews and task show up only halfway
- amarock equalizer freezes (though music playback continues)
- my ftp server slows down to a crawl
- ...

There are phases (some minutes), when everything seems normal, but then again there are phases, where the computer locks up a millisecond after my last keypress. A single freeze can last from only a few seconds up to hours. It immediately stops and reacts normally again, as soon, as I touch the touchpad or press shift or any other key. It won't loose keypresses, so if I type a letter, they all arrive in the textbox. Only sometimes, I can type "a letter late", that is the textbox draws the previous letter, when it's freeze is briefly released by the current keypress.

All this started with updating to 2.6.22-* kernel. In fact, for my daily work I still go back to 2.6.20-16.32-generic. the 2.6.24-* series has the advantage, of booting without my assistance. The 2.6.22.* would only boot if I pressed shift whenever it hung up. In addition, 2.6.24-* will accept a normal keyboard repeat, while 2.6.22-* accepted only the first keypress, without repeating it automatically while my finger still kept it pressed. But still, 2.6.24-* won't shut down without some keystrokes.

Lets see, what else do you need ... I've mentioned my problem in bug #123789 which is about to close. That's why I open my own now.

My laptop is a Samsung R40plus with dual-core Intel processor, 2 GB RAM and 160 GB hdd, ati graphics is on board. 3D-acceleration works ... but its not useful, if the game hooks up ever few seconds.

Switching back and forth between kernel 2.6.20 and 2.6.24 definitely toggles this bug on and of (proved over the last month)

In /var/log/messages I could not spot relevant error messages.

Thanks for your time and effort
Holger

---

> uname -a
Linux samson 2.6.24-19-generic #1 SMP Fri Jul 11 23:41:49 UTC 2008 i686 GNU/Linux

> cat /proc/version_signature
Ubuntu 2.6.24-19.36-generic

> cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu 8.04.1"

> cat /proc/swaps
Filename Type Size Used Priority
/dev/sda1 partition 1951856 0 -1

[Leann Ogasawara (leannogasawara)]

The Ubuntu Kernel Team is planning to move to the 2.6.27 kernel for the upcoming Intrepid Ibex 8.10 release. As a result, the kernel team would appreciate it if you could please test this newer 2.6.27 Ubuntu kernel. There are one of two ways you should be able to test:

1) If you are comfortable installing packages on your own, the linux-image-2.6.27-* package is currently available for you to install and test.

--or--

2) The upcoming Alpha5 for Intrepid Ibex 8.10 will contain this newer 2.6.27 Ubuntu kernel. Alpha5 is set to be released Thursday Sept 4. Please watch http://www.ubuntu.com/testing for Alpha5 to be announced. You should then be able to test via a LiveCD.

Please let us know immediately if this newer 2.6.27 kernel resolves the bug reported here or if the issue remains. More importantly, please open a new bug report for each new bug/regression introduced by the 2.6.27 kernel and tag the bug report with 'linux-2.6.27'. Also, please specifically note if the issue does or does not appear in the 2.6.26 kernel. Thanks again, we really appreicate your help and feedback.

[private_lock (private-lock)]

Hello Leann Ogasawara!

First I further investigated the symptoms: The 2.6.24 kernel switches between a "good" and a "bad" state. I can tell them apart by looking at the CPU-diagram in the lower right. As long, as the yellow line touches the blue area of cpu/user, everything works as expected. But if there is a thick brown divider of cpu/sys between blue and yellow, I experience all the described problems.

Though the screenshot includes the table of KSysGuard, I could not really relate the brown area to the "System %"-column. During "bad"-state XOrg would take up to 8% and a bunch of other applications use 1 or 2 %. But in "good"-state, this did not drop to zero as one could think by looking at the graph (I admit, it significantly reduced: Xorg 3% and maybe 2 apps 1% each).

To get a clean and stable diagram I had my finger on the touchpad constantly shifting the mouse a few pixel here and there. The width is approximately 4 min 30 sec. Against my expectations, I found those two states quite stable. It would not switch all by itself. To trigger a switch I had to do some trivial actions like:
- trigger a tooltip
- scroll a window
- switch active app via Alt+Tab

[private_lock (private-lock)]

Next I installed http://packages.ubuntu.com/intrepid/linux-image-2.6.27-2-generic

First the good news: This kernel almost works! Concerning my original bug-report: my system didn't really freeze over the last 3 hours. The desktop experience is a lot better, but still not perfect. Animated gifs are still not going smoothly and also pressing and holding a key, the repeat rate stutters. It seems the stalls are now limited to some milliseconds in length. About once a minute, the turning sphere from http://www2.forennet.org/images/faces/avatar-444.gif "slows down" drawing some frames in slow-motion. Though there is not more than 15% CPU-usage total, I get the impression, the system is heavily occupied.

In addition there is a multitude of other issues:
- most annoying: NO SOUND ... seems to be the same as: https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.17/+bug/68659
- no 3D-acceleration -> I guess I have to wait for ATI to compile their latest drivers for the 2.6.27 kernel
- no VirtualBox -> waiting for Sun
- http://userweb.kernel.org/~dtor/eviocgbit-bug.html -> it seems my synaptics touchpad driver needs an update

I really appreciate, how easy it was to switch the kernel. Which one shall I try next?
private_lock

[Leann Ogasawara (leannogasawara)]

Thanks private_lock,

Seems like the newer kernel is showing improvement regarding to this bug. Newer versions of the Intrepid kernel will continue to be released. You can probably monitor https://edge.launchpad.net/ubuntu/+source/linux/ to see which kernel will be released next. Please keep us posted with any testing updates. Thanks.

[Launchpad Janitor (janitor)]

Per a decision made by the Ubuntu Kernel Team, bugs will longer be assigned to the ubuntu-kernel-team in Launchpad as part of the bug triage process. The ubuntu-kernel-team is being unassigned from this bug report. Refer to https://wiki.ubuntu.com/KernelTeamBugPolicies for more information. Thanks.

[Jeremy Foshee (jeremyfoshee)]

This bug report was marked as Triaged a while ago but has not had any updated comments for quite some time. Please let us know if this issue remains in the current Ubuntu release, http://www.ubuntu.com/getubuntu/download . If the issue remains, click on the current status under the Status column and change the status back to "New". Thanks.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]

[private_lock (private-lock)]

Currently running:

> uname -a
Linux Samson 2.6.31-20-generic #58-Ubuntu SMP Fri Mar 12 05:23:09 UTC 2010 i686 GNU/Linux

It seems quite fine. Booting, suspend and shutting down mostly work without me providing additional presses on shift. Sometimes I just get too eager and press it anyway out of a bad habit :-)

I haven't seen the other symptoms in a long time working with KDE 4.4.1 now.

Please close this bug and move on to more pressing issues :-)