On Wed, May 12, 2021 at 6:12 AM Axel Rasmussen <axelrasmussen@xxxxxxxxxx> wrote: > Is some combination of bpf and kprobes a possible solution? There are > some seemingly relevant examples here: > https://github.com/iovisor/bpftrace/blob/master/docs/tutorial_one_liners.md > > I haven't tried it, but it seems like attaching to handle_userfault() > would give similar information to perf_count_sw_page_faults, but for > userfaults. That would probably work in some cases, but as Kyle said that requires privileges and currently rr can run unprivileged (if you set perf_event_paranoid to 1 or less) and usually does. Also, AFAIK, kprobing handle_userfault would not be a stable ABI. Rob
