Comment 42 for bug 1396654

Hmm, apparently /usr/bin/perf is only a wrapper script that runs the "right" version of the perf executable for the current kernel. But the perf executable (typically inside /usr/lib/linux-tools-VERSION) is part of the "linux-tools-VERSION" package.

So if I do:
$ sudo apt install linux-tools-4.15.0-47/bionic-proposed

and then run /usr/lib/linux-tools-4.15.0-47/perf directly, instead of the wrapper script which will still run the perf version for the LTS kernel, things finally work here.