Sporadic UI halts on Meerkat Netbook - how to debug

[Milan Bouchet-Valat]

Le lundi 04 octobre 2010 à 21:42 +0300, Mikko Ohtamaa a écrit :
> Hi,
> 
> 
> 
> I am trying Maverick Meerkat Netbook remix on Asus 1005HA Eee Pc. I
> like it. Finally the Linux desktop is going to right direction.
> 
> 
> However, I am having some "slowdown" issues. Once in a while (...or
> many times during an hour) everything besides the mouse cursor in the
> user interface halts. The text cursor stops blinking (no matter what
> application). I suspect this might have something to do with disk IO
> as the netbook has very slow disk and I have encrypted home folder.
> Each halts last 5-10 seconds and since they happen often they hit hard
> the overall user experience. Basic tasks like editing the text on the
> computer become pain.
These are the typical symptoms of an I/O bug nobody has been able to
identify and which has generated many comments. See
https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.22/+bug/131094
but don't expect to find help there, as we don't even know whether there
are several bugs mixed or a single root cause... :-(

> I have some background tasks running (Skype, Quassel), but it should
> be nothing killing the performance. Windows XP can handle things just
> fine.
The only thing that is likely to create a high I/O load regularly is
swapping. I'd suggest you avoid running too many programs at the same
time. You can use the command 'free -m' to see how many free RAM you
have.

> Now, my question is, how to debug these "halt" or "stop" issues. I
> suspect if I could get history graph of CPU and IO per application
> level it would help greatly. Also, the problem might be in kernel
> services (disk io, OpenGL, sound?) . 
If your problem is actually the swapping + I/O bug issue, I don't think
you can do much to help, except if you have enough skills to convince
kernel developers that they can do something about it. If you're ready
to answer a long series of technical questions, then you can send a mail
to the kernel development list (lkml.org).

But before that, it would be useful to check that system logs don't show
something interesting each time you suffer from the bug (use
System->Administration->Log viewer and have a look at these files). Also
running the command 'top' and checking what applications are using RAM
may simply reveal that one of them is leaking memory (type '<<' to sort
processes by order of physical RAM usage).


Regards