In this talk Valerii Kravchuk is talking about tracing and profiling MySQL / MariaDB in production on recent Linux versions. This include usage of modern Linux tracing tools like ftrace, perf and eBPF (via bcc tools and bpftrace). So, tracing is basically doing something whenever specific events occur. Event data can come from the kernel or from userspace (apps and libraries). Some of them are automatically available without further upstream developer effort, others require manual annotations. You can download the PDF of this talk here