Public bug reported: 1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
16.04 LTS 2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center Tried booting various versions between the 4.13.0-lowlatency and 4.15.0-lowlatency versions. Can confirm the problem appears on all 4.15.0 versions (e.g., 4.15.0-13), but is not present on any 4.13.0 version (e.g., 4.13.0-45). The version of Xen used is 4.9.0-0ubuntu3. I believe this isn't in Xenial's repositories, but actually from a later Ubuntu release, since I wanted some features of Xen that weren't in Xenial's version. Bisecting the commits narrowed down to the issue appearing after http://kernel.ubuntu.com/git/ubuntu/ubuntu-xenial.git/commit/?h=hwe- edge&id=a62a7117d91ca83d319566cbe16039f4e9f413c2 was committed. In fact, after recompiling and running the latest hwe-edge kernel (4.15.0-23) with that commit reverted, the problem disappears. This kernel is attached. I also intend to test the mainline kernel, but I haven't gotten around to it yet 3/4) What you expected to happen/What happened instead The newer kernel to not be significantly slower than the older kernel (I'm aware of Meltdown/Spectre mitigations causing slowdowns, but it should not be *this* much slower). Specifically, after upgrading to a 4.15.0 kernel from 4.13.0, I noticed these behaviours: - Time to log in via lightdm seems to have doubled in time or more (I did not actually time it, but it is taking significantly longer) - Scrolling in the Processes tab of system-monitor is noticeably choppy and laggy - The "user experience" in general seems to be laggy - Running a game in a Windows domU (with passthrough GPU) resulted in ~25% of the original FPS Interestingly, if I boot on bare metal (i.e., without Xen), the problem does not manifest. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: linux-image-4.15.0-22-lowlatency 4.15.0-22.24~16.04.1 ProcVersionSignature: Ubuntu 4.15.0-23.25~16.04.1-lowlatency 4.15.18 Uname: Linux 4.15.0-23-lowlatency x86_64 ApportVersion: 2.20.1-0ubuntu2.18 Architecture: amd64 CurrentDesktop: GNOME-Flashback:Unity Date: Fri Jun 29 21:46:35 2018 SourcePackage: linux-signed-hwe-edge UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: linux-signed-hwe-edge (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug third-party-packages xenial ** Attachment added: "linux-image-4.15.0-23-lowlatency with offending commit reverted" https://bugs.launchpad.net/bugs/1779305/+attachment/5157763/+files/linux-image-unsigned-4.15.0-23-lowlatency_4.15.0-23.25~16.04.1-a62a7117d91ca83d319566cbe16039f4e9f413c2-reverted_amd64.deb -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1779305 Title: Sluggish performance as Xen dom0 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe-edge/+bug/1779305/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
