It's already being used :). That said, I've talked to the upstream kernel maintainers about the ability to attach a blog program to ptrace, which could possibly

It's already being used :). That said, I've talked to the upstream kernel maintainers about the ability to attach a blog program to ptrace, which could possibly improve performance for the ping pong case if made sufficiently general. That's also the crux though, since sufficiently general probably means eBPF, which is still not considered safe for unprivileged use cases.