Comment 233 for bug 620074

Jens,

I'm trying to nail this down on my computer. So, I'm creating a vm of my i686 gentoo system, to see if I can see the same results as I was before.

I used the following command, inside the vm, to extract my system tarball backup of my previous system.

ssh root@192.168.8.4 'gunzip -c /media/backup/system.tar.gz' | tar -xv --exclude './usr/portage/packages/*' --exclude './userportage/distfiles/*' --exclude './var/log/apache2/*' --exclude ./Bonnie.10218 >extract-list.txt

Now, on the host system (192.168.8.4) I am seeing the following...
trenta@tdamac ~/Desktop $ uptime
 01:39:37 up 1:21, 6 users, load average: 20.49, 14.92, 9.35

Obviously I'm getting REALLY sick performance. Normally something linear like a tar extraction does not produce these kinds of issues with performance. Granted that the disk may have to move around a little, but is it that bad?.

Is there some sort of thing I can do, to analyze why this is happening? e.g. something like strace, or something? I ran strace -c on kwrite, during heavy load like this, and it claims that it finished everything in a tenth of a second, even though it took like 30.

So, is there a lower level mechanism I can use to get a fix on what is making processes wait? For example, something that will tell me "kernel function X" is blocking?

Thanks.