Comment by postgresperf

Optimizing a multi-layer cache system is a Complex System task with no subset you can reduce to a simpler version of the problem. PG has a 3 layer cache--database, OS, storage--and when you combine that with concurrency and locality, you have a giant 5 dimensional space to map out. Building the right set of benchmarks for PG with guidance for the most important parts to navigate fro that space has kept me busy for 20 years now.