Static tracing with usdt

[mzr]

Long polls and starved tasks can be tricky to identify. tokio-console as far as I understand is a great attempt to provide more insight into tokio's executor. However, it requires tracing. It's not always easy to start using tracing e.g. if it conflicts with glog, and requires non-trivial migration. I was thinking perhaps features similar to tokio-console, can be achieved with some static probes, and a bpftrace script. For example, a probe just before a call to poll on a future and right after it exits. I don't know much about tokio internals, so I come with a question, would this fly?