I believe performance tuning (or even testing) is one the most challenging for an engineer. Well, in lots of company, this is the lowest priority than others "important" thing.

My purpose of opening this post is to know what do you think*good* performance engineer should have.

I can list some things like:

1. Solid database,programming knowledge.
2. Do single thread performance testing.
3. Good knowledge of using the load generator tools to simulate the concurrent loads.
4. Use different tools to monitor/measure the app/db server performance status
5. Understand and can debug the codes. Even tune the codes.

Any more ideas are always appreciated!