Public bug reported: There is a regression in the 4.4.0-42 kernel update that is still present in the latest 4.4.0 update. I have verified that this appears in Ubuntu 16.04 and Ubuntu 14.04 (with ubuntu-xenial kernel installed) amd64. I also suspect this happens in default Ubuntu 16.10 kernel as well, but i have not tested.
4.4.0-38 did not have this issue. in 4.4.0-42 and newer, perf records incorrect timestamps which can be verified by running this command: $ perf record -a -e sched:sched_-k CLOCK_MONOTONIC switch stress -c 10000 -t 10 stress: info: [25560] dispatching hogs: 10000 cpu, 0 io, 0 vm, 0 hdd stress: info: [25560] successful run completed in 6s [ perf record: Woken up 16 times to write data ] Warning: 78487 out of order events recorded. Note that the warning about out of order events is a symptom of this problem and is not expected to happen. This does not happen(correct behavior) if i run 4.4.0-38 and older, or if i run a fully patched upstream 4.4.35 kernel instead. This regression has already been fixed upstream but has not been included in ubuntu-xenial kernel yet. Upstream fix is here: https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=78c7b55b362e868e529ab6579134708fcf5539dd ** Affects: linux (Ubuntu) Importance: Undecided Status: Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1645449 Title: Linux perf regression in 4.4.0-42 and newer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1645449/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
