Building Burstables: cpu slicing with cgroups

Burstable VMs run on a fraction of CPU and burst to a higher level of CPU usage to support occasional usage spikes. To implement them, we leveraged Control Groups v2 (cgroups v2), a Linux kernel feature that helps manage resource usage. We thought our open-source implementation of burstable VMs might be interesting enough to write about. We also learned a lot about Linux cgroups in the process!