When you get into the details I found it hard to come away with any strongly actionable takeaways though. Perhaps the most interesting lesson/reminder is this: it takes a lot of effort to tune a Linux kernel. For example:

“Red Hat and Suse normally required 6-18 months to optimise the performance an an upstream Linux kernel before it can be released as an enterprise distribution”, and
“Google’s data center kernel is carefully performance tuned for their workloads. This task is carried out by a team of over 100 engineers, and for each new kernel, the effort can also take 6-18 months.”