Prepare environment for experiments #

Before starting, I want to be on the same page with the reader so that any example or code snippet can be executed, compiled, and checked. Therefore we need a modern GNU/Linux installation to play with code and kernel.

If you are using Windows or Mac OS, I would suggest installing Vagrant with Virtual Box. For the GNU/Linux distributive, I’d like to use Arch Linux. Arch is a good example of an actual modern version of the GNU/Linux system (BTW, I use Arch Linux). It supports the latest kernels, systemd and cgroup v2.

If you’re already on Linux, you know what to do 😉.

Can I use docker?

Unfortunately, no. We need a system where we can go nuts and play around with cgroup limits, debug programs with low-level tools and run code as a root user without any limitations.

So below, I’m showing all you need to install on Arch.

Arch Linux provisioning #

When you get your Arch running, please update it and install the following packages:

$ pacman -Sy git, base-devel, go

We need to install yay (https://github.com/Jguer/yay) in order to be able to setup software from community-driven repositories:

$ cd ~
$ git clone https://aur.archlinux.org/yay.git
$ cd yay
$ makepkg -si

Install vmtouch tool from aur:

$ yay -Sy vmtouch 

We will need page-type tool from the kernel repo, so the easiest way to install it is to download the linux kernel release and make it manually:

$ mkdir kernel
$ cd kernel
$ wget https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/snapshot/linux-5.14.tar.gz
$ tar -xzf linux-5.14.tar.gz
$ cd linux-5.14/tools/vm
$ make
$ sudo make install

Now we are almost ready. We need to generate a test data file, which will be used in our experiments with Page Cache:

$ dd if=/dev/random of=/var/tmp/file1.db count=128 bs=1M  

And the final step is dropping all linux caches in order to get a clean box:

$ sync; echo 3 | sudo tee /proc/sys/vm/drop_caches