Public bug reported:
Binary package hint: linux-generic
I am not at all sure this is a kernel bug, but I don't know what else to
file it against. Perhaps someone who understands the VM subsystem could
look at my logs and provide some indication of what may be the culprit
here.
Symptoms:
At apparently random times when I am working, the system will be come
extremely slow. This frequently occurs on starting a new application,
which may be Firefox, Open Office or Okular for example. The load
average spikes to a large value (greater than 10) and the hard drive
light lights up, showing continuous disk I/O. The user interface
becomes unusable and the mouse pointer update is very slow (several
seconds lag). More often than not the system becomes so unresponsive
that I cannot change to a text VT and kill X, or even use ctrl-alt-
bkspace. I have to resort to Magic-SysRq-RSEIUB and reboot.
This is happening several times a day on a system with 2GB of RAM under
a light workload of KDE4.2, Thunderbird, Firefox and sometimes
OpenOffice or Netbeans. At the time of onset the memory usage as shown
by 'htop' is around 400MB used of 2GB physical (this excludes 'cached').
It is impossible to predict just what action may start a frenzy of disk
activity and a loss of responsiveness. Sometimes even opening a page in
an existing Firefox instance is sufficient to effectively DOS the
system. **IMPACT IS SEVERE**
I am currently running up-to-date Jaunty with kernel 2.6.28-11, but I
have had similar behaviour with Intrepid in the past. I believe that
upgrading this machine from 1GB to 2GB has made matters worse. I have
no swap device configured, but I have tried configuring swap in the past
using a swapfile, and this has not prevented the problem from occurring.
My confusion is what could be causing the disk I/O that is bogging down
the system, and driving the load average up as processes wait on I/O?
It can not be swap in the sense of using a swap partition or file, since
I have none configured. I don't have any reason to believe it is
application I/O either - the problem occurs on starting many different
apps, and appears to be triggered by requesting more memory. I can only
think it is paging executables / shared libs in and out, trying to make
room. I can't understand why this is happening, with so my physical
memory free.
Logs:
This problem has proven difficult to diagnose because usually when it
occurs I lose control of the machine and existing programs like top and
so on stop updating. I grabbed a little script from another thread on
Launchpad which runs 'top' and 'vmstat' and dumps the output to a file.
Today I had this script running while I had a 'high load average' event.
In this case, I did not lose control of the machine as sometimes
happens, but the load average spiked to 6 or so for no apparent reason.
Running KDE 4.2, with Thunderbird open and maybe two Dolphin windows.
Started OpenOffice Word Processor - it took maybe 5 mins to start it and
shut it down. Meanwhile load average is 6 or so, and mouse pointer
unresponsive, disk is thrashing. Once OO had shut down, the thrashing
stopped. I was able to repeat this behaviour by starting OO Calc, which
also took minutes to start up and shut down. During this time, I was
logging 'top' and 'vmstat' output, which I will attach to this bug. The
script logs 'vmstat 1' and 'top -b -d 1' to 'vmstat.log' and 'top.log'
respectively.
I am not sure what other evidence I can capture. I noticed that 'iotop'
showed OO was reading from disk at around 5MB/s when the disk was
thrashing. What it could be reading @ 5MB/s for several minutes I
cannot imagine, unless pages are being thrashed in and out of memory for
some reason.
Can someone understand my log files and point to the offending process?
If you can suggest other information to capture, please let me know. I
am an experienced Linux user and I am happy to spend some time on this
as it is rendering my main development machine unusable!
I don't think this problem is tied to a memory leak in any particular
user-space end-user application (although it could be a leak of some
sort in the X-Server or KDE4 components).
Hardware:
HP Pavilion dv1680ea
Core Duo 1.87GHz
2GB RAM
Intel integrated graphics
Software:
Kubuntu 09.04 2.6.28-11 kernel
KDE 4.2
Firefox 3.0.9, OOo 3.0 and other apps
NO SWAP CONFIGURED
** Affects: linux-meta (Ubuntu)
Importance: Undecided
Status: New
--
High load average, disk read, no apparent reason - 2.6.28-11
https://bugs.launchpad.net/bugs/367377
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
--
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
