Message12618

I noticed I'd somewhat duplicated this in #2778. I didn't spot it as a duplicate because of the title majoring on "runtime instrumentation", whereas richer logging is what's really on my mind in #2778.

I'm not sure what "runtime instrumentation" means, but I'm working on the assumption that if we get the logging in place (with timestamps, the instrumentation needed is a thing that consumes it.

Logging is not the right mechanism if investigation needs micro-benchmarks, but it is good for finding what phases of start-up, or an application, are costly.