User::pingLimiter() let us limit some actions (default: 'edit'). The wfProfileIn() entry point does not vary by action. The related statsd metric generated on Wikimedia cluster is MediaWiki.User.pingLimiter
We had an incident beginning of May 2014 which had some thumb rendering action being limited. Having a graph dedicated to that action would have help spot the action being throttled.
We can probably just:
wfProfileIn( METHOD );
wfProfileIn( METHOD . '-' . $action );