Introduce way to inject metrics?

[dantleech]

It would be good to be able to f.e. add the number of DB calls to the reports.

[jbboehr]

I'd love to see this implemented.

I've been working on an extension to read some PMU counters using the perf_event_open syscall[0], including some really juicy ones like PERF_COUNT_HW_INSTRUCTIONS and PERF_COUNT_HW_CPU_CYCLES (sadly, Linux-only).

I played around a bit with a custom executor, but it would be nice to be able to do it with the built-in executors somehow.

Let me know if I can help at all.