448557 2022-01-15 22:00:48 +0000 kwin_wayland constantly consuming 20-60% of a CPU core recently when using AMS cursor 2022-01-22 20:42:48 +0000 1 1 4 Plasma kwin wayland-generic git master Other Linux RESOLVED FIXED efficiency-and-performance HI major --- 1 nate kwin-bugs-null auxsvr herzenschein keith postix xaver.hugl https://invent.kde.org/plasma/kwin/commit/547bb52c6c3833d76bbffef46fa9b3f3ae51dccf 5.24 0 oldest_to_newest 2094163 0 nate 2022-01-15 22:00:48 +0000 I build all KDE stuff from git master every day, and for at least the last two days, kwin_wayland has been consuming between 20 and 60% of a CPU core at idle. It causes input lag and makes the system nearly unusable. I attempted to bisect but was unable to due to tight coupling between KWin and its dependencies. The journal log doesn't have anything fishy-looking in it. I'm not sure how to debug this but can provide any logs. 2094169 1 nate 2022-01-15 22:11:27 +0000 kwin_x11 is unaffected. I've temporarily gone back to X11 to have a usable system. 2094404 2 nate 2022-01-16 15:39:02 +0000 This seems to have been fixed with a mesa update today. 2094828 3 nate 2022-01-17 19:40:20 +0000 Never mind, it turned out that that didn't fix it. However, after some investigation in #kwin, setting `KWIN_DRM_NO_AMS=1` *did* fix it. So it looks like this isue is related to eprformance issues with the AMS cursor. Re-opening. 2094830 4 keith 2022-01-17 19:55:01 +0000 (In reply to Nate Graham from comment #3) > Never mind, it turned out that that didn't fix it. > > However, after some investigation in #kwin, setting `KWIN_DRM_NO_AMS=1` > *did* fix it. So it looks like this isue is related to eprformance issues > with the AMS cursor. Re-opening. I am also impacted by this. Nate's workaround seems to work for me. Note that previous to the workaround, in addition to the CPU consumption from kwin_wayland, I was unable to create new desktops and switch between existing desktops using the overview effect. The workaround seems to have fixed that issue as well. 2094958 5 bug-janitor 2022-01-18 10:23:10 +0000 A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/1904 2095212 6 bug-janitor 2022-01-18 21:52:29 +0000 A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/1907 2095316 7 xaver.hugl 2022-01-19 10:52:00 +0000 Git commit 50c167c94b33702f3f026e007bda424ec1af047d by Xaver Hugl. Committed on 19/01/2022 at 10:31. Pushed by zamundaaa into branch 'master'. backends/drm: fix reallocation check When no modifiers are used at all, we shouldn't check them. M +2 -1 src/backends/drm/egl_gbm_backend.cpp https://invent.kde.org/plasma/kwin/commit/50c167c94b33702f3f026e007bda424ec1af047d 2095458 8 vlad.zahorodnii 2022-01-19 17:25:11 +0000 Git commit 547bb52c6c3833d76bbffef46fa9b3f3ae51dccf by Vlad Zahorodnii, on behalf of Xaver Hugl. Committed on 19/01/2022 at 17:25. Pushed by vladz into branch 'Plasma/5.24'. backends/drm: fix reallocation check When no modifiers are used at all, we shouldn't check them. (cherry picked from commit 50c167c94b33702f3f026e007bda424ec1af047d) M +2 -1 src/backends/drm/egl_gbm_backend.cpp https://invent.kde.org/plasma/kwin/commit/547bb52c6c3833d76bbffef46fa9b3f3ae51dccf 2095480 9 nate 2022-01-19 18:26:50 +0000 That completely fixes the problem for me, hooray! kwin_wayland is once again down to 0% CPU most of the time, with occasional spikes to 10%. 2096919 10 postix 2022-01-22 20:42:48 +0000 Do you know if these changes are already in KDE Neon Testing?