Because I've run
make deb-pkg so many times, I've started to see exactly where
it starts to slow down even with really large machines. Observing cpu usage, I
noticed that many parts of the build were serialized on a single core. Upon
further investigation I found the following.
Let's say you've messed up your MAAS installation and have no idea how to
recover data about your nodes. Have no fear, you can access the django managed
Occasionally it is useful to debug a running guest VM's kernel. Setup your host
machine for virtual machine hosting with QEMU/KVM, and add ddebs to your host
system using this wiki.
GCOV/LCOV are amazing tools to figure out code coverage in the Linux kernel. It
is fairly trivial to setup on your own machine. First, enable the following in
your kernel configuration:
Debugging hung machines can be a bit tricky. Here I'll document methods to
trigger a crashdump when these hangs occur. What exactly does it mean when a
machine 'hangs' or 'freezes-up'? More information can be found in the kernel
documentation, but overall there are really a few types of hangs.
Bisecting the kernel is one of those tasks that's time-consuming and error prone.
Ktest.pl is a script that lives in the linux kernel source tree that helps
to automate this process. The script is extremely extensible and as
such takes time to understand which variables need to be set and where. In this
post, I'll go over how to perform a kernel bisection using a VM as the target
machine. In this example I'm using 'ubuntu' as the VM name.
CRIU stands for Checkpoint/Restart in Userspace. As the criu package should
be landing in Utopic soon, and I wanted to test drive it to see how it handles.
New live kernel patching projects have hit LKML recently here and
here, and I've taken the opportunity to test drive kGraft with the Ubuntu
kernel. This post documents how to get a sample patch working.