[maemo-users] Maemo IU locking up

From: Torsten Hoefler maemo-users at unixer.de
Date: Fri Jun 6 10:33:13 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.)
so, after some debugging time, I finally found the problem. It were the
desktop applets (homeip and friends). I really liked them a lot because
I like to have different status information (so I had all of them
enabled). But they are kind of evil because:
1) they drain the battery (I never had more than one day standby, now,
   after disabling them it's the 3-5 days that it should be)
2) they caused growing CPU load (by running maemo-launcher), I suspect
   they executed scripts or sonething to gather their information
3) they caused the device to lock up UI-wise
4) they caused indeterministic reboots (watchdog) of the device

All those problems went away after I disabled the applets. Sad but true.

Thanks a lot for your help!


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