From a single bit
to putting your finger on the bottleneck

A cache is a desk drawer; the memory hierarchy is how far you have to walk to the warehouse. Unfamiliar ideas are explained in terms of things you already know.

You really do type lscpu · vmstat · iostat. You also put the server under load and break it.

Write assembly for the miniature CPU and watch fetch, decode and execute one step at a time.

How to tell, within three minutes of meeting a slow server, whether it is the CPU, the disk or memory.