[maemo-users] Maemo IU locking up

From: Eero Tamminen eero.tamminen at nokia.com
Date: Fri May 30 19:27:04 EEST 2008

ext Marius Gedminas wrote:
> On Thu, May 29, 2008 at 06:26:56PM -0400, Torsten Hoefler wrote:
>> I am running the newest OS2008 on a N810. And I have problems with the
>> OS (I guess). The IU locks up from time to time with 100% CPU load (the
>> CPU load applet shows full system load) and pretty much stops
>> responding. I can not open any windows anymore (it just draws the white
>> background after a delay of >30 seconds but no widgets).
>> This happens from time to time (after several hours) also when I don't
>> use the device (also in offline mode), i.e., it's just sitting around
>> doing nothing. Something seems to use the CPU extensively because the
>> battery is drained quickly (2-3hrs) after it starts.
>> I tried to debug via ssh, and see a constant system load >2 but no
>> process besides "maemo-launcher" consuming about 20% (why does this
>> process run all the time? What does it do?). I also see Xomap from time
>> to time (what does this do?). It looks like top (running as root) is not
>> showing all the processes? Is this possible?
> I've noticed that the kernel itself sometimes uses a lot of CPU to
> perform JFFS2 garbage collection, a while after you write/delete a lot
> of files.  If I'm not mistaken, and that's the case, it could explain
> why the CPU is 100% busy, but top doesn't see any process keeping it
> that busy.

You should see the jffs2 gcd and pdflush kernel threads also in top.

(There's a bug about a thing like that in bugs.maemo.org and so far
the reason would seem to be having too much (for jffs2) file system
modifications too often. Unfortunately there's not too much that could
be done to improve that, jffs2 just works like that and there are not
yet good & mature enough alternative file systems for flash. Only thing
you can do is reduce writing to the jffs2 root file system, switch off
or do less often automated rss and email fetching, make sure that you
have memory card with enough space when streaming youtube or other
videos so that they are not buffered to internal flash etc.)

> Check kernel messages with dmesg, perhaps there will be some clues
> there?

	- Eero

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