I have this problem as well on Cinnamon, so it doesn't appear to be specific to KDE. It stalls often and frequently over 15-30 seconds at a time for no apparent reason. But the swapping to disk may be a clue.
I see this on 5.4.0-40 and have also tried with the lowlatency version of the kernel and it doesn't help. One thing that seems to reduce the frequency of the problem somewhat is to disable transparent_hugepage support but it still happens even after that. I have 32GB ram and it starts happening when I get to about 50% ram (mem available) usage. The system also appears to start swapping at that point despite what swappiness is set to. I tried setting it to 10 but it is still swapping at what appears to be ~ 50% usage. It appears to be very easy to reproduce if you run a few VMware VMs on a system. # cat /proc/sys/vm/swappiness 10 $ free -m total used free shared buff/cache available Mem: 31030 6591 246 9050 24192 14936 Swap: 32767 4942 27825 $ cat /proc/meminfo MemTotal: 31774792 kB MemFree: 256768 kB MemAvailable: 15324804 kB Buffers: 5887324 kB Cached: 16712984 kB SwapCached: 488276 kB Active: 19816476 kB Inactive: 8835508 kB Active(anon): 12801324 kB Inactive(anon): 2522936 kB Active(file): 7015152 kB Inactive(file): 6312572 kB Unevictable: 145612 kB Mlocked: 48 kB SwapTotal: 33554428 kB SwapFree: 28493052 kB Dirty: 2301336 kB Writeback: 9564 kB AnonPages: 6161528 kB Mapped: 7931416 kB Shmem: 9272240 kB KReclaimable: 2201904 kB Slab: 2451272 kB SReclaimable: 2201904 kB SUnreclaim: 249368 kB KernelStack: 21552 kB PageTables: 85272 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 49441824 kB Committed_AS: 30098296 kB VmallocTotal: 34359738367 kB VmallocUsed: 55400 kB VmallocChunk: 0 kB Percpu: 7712 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB ShmemHugePages: 0 kB ShmemPmdMapped: 0 kB FileHugePages: 0 kB FilePmdMapped: 0 kB CmaTotal: 0 kB CmaFree: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB Hugetlb: 0 kB DirectMap4k: 5078656 kB DirectMap2M: 27346944 kB DirectMap1G: 0 kB ** Changed in: linux (Ubuntu) Status: Invalid => Confirmed -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1852001 Title: KDE GUI freeze on high disk IO Status in linux package in Ubuntu: Confirmed Bug description: I've got massive problems with GUI on my PC. The attached logs are from the following setting: - high disk load (f3write) - kernel 4.15.0-1050-oem (the only 4x kernel available in eoan) - no swap available These are the parameters (disk load, kernel, swap) I am fiddling with to find out the cause, see below. In general - the problem happens once a day with any 5.0 or 5.3 kernel from eoan repo - more likely to happen with high disk or CPU load, but not necessarily. - less likely with the 4.x kernel mentioned above. I just installed the following kernels from kernel-ppa: 5.3.10-050310-generic 5.4.0-050400rc6-generic 5.4.0-997-generic (drm-intel-next) Now I am waiting for the freeze to occur again. The problem started about half a year ago. There have been three changes that happened at the time and could be the cause - switch to kernel 5.x - update to Ubuntu 19.4 - swapped motherboard, CPU and RAM. The hassle started with the following scenario, repeated often: - high disk load - PC becomes laggy - soon dies/freezes The longer I waited, the deeper the lockdown went. but I don't know the exact details. The first cause I found was kswapd running amok and take the system with it. Workaround: add swap space. Now the problem shifted: Whenever I got high disk load (eg dd 100 GB of data) the kernel swaps likle crazy and makes the GUI first lag soon freeze. but no excessive CPU load any more, as kswapd does not go crazy. Again I found a workaround: the above mentioned 4.x kernel. In this case the GUI lags as expected from a heavily swapping system. nothing more. but still sometimes the GUI simply freezes (the error reported at the top) Another workaround is to completely remove swap. Let's see what happens, if kswapd goes amok again. I am not sure as how these problems are related. I did extensive hardware check like - memtest86 newest version, no "may be vulnerable to high frequency row hammering" - smart do you suggest any burn in test suites? thanks ProblemType: Bug DistroRelease: Ubuntu 19.10 Package: xorg 1:7.7+19ubuntu12 ProcVersionSignature: Ubuntu 4.15.0-1050.57-oem 4.15.18 Uname: Linux 4.15.0-1050-oem x86_64 ApportVersion: 2.20.11-0ubuntu8.2 Architecture: amd64 Date: Sun Nov 10 15:55:14 2019 DistUpgraded: 2019-10-19 13:35:30,394 DEBUG entry '# deb http://ppa.launchpad.net/brandonsnider/cdrtools/ubuntu cosmic main # disabled on upgrade to eoan' was disabled (unknown mirror) DistroCodename: eoan DistroVariant: ubuntu DkmsStatus: virtualbox, 6.0.14, 5.3.0-18-generic, x86_64: installed virtualbox, 6.0.14, 5.3.0-19-generic, x86_64: installed ExtraDebuggingInterest: Yes GraphicsCard: Intel Corporation UHD Graphics 630 (Desktop 9 Series) [8086:3e98] (prog-if 00 [VGA controller]) Subsystem: Micro-Star International Co., Ltd. [MSI] UHD Graphics 630 (Desktop 9 Series) [1462:7b16] InstallationDate: Installed on 2017-12-16 (693 days ago) InstallationMedia: Kubuntu 17.10 "Artful Aardvark" - Release amd64 (20171017.1) MachineType: Micro-Star International Co., Ltd. MS-7B16 ProcEnviron: LANGUAGE=en_US:en TERM=linux PATH=(custom, no user) LANG=de_DE.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-1050-oem root=UUID=ca93bfbd-335a-4cc7-9d0f-f0da18447497 ro quiet splash vt.handoff=7 SourcePackage: xorg Symptom: display Title: Xorg freeze UpgradeStatus: Upgraded to eoan on 2019-10-19 (22 days ago) dmi.bios.date: 08/13/2019 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 2.80 dmi.board.asset.tag: Default string dmi.board.name: B360 GAMING PRO CARBON (MS-7B16) dmi.board.vendor: Micro-Star International Co., Ltd. dmi.board.version: 1.0 dmi.chassis.asset.tag: Default string dmi.chassis.type: 3 dmi.chassis.vendor: Micro-Star International Co., Ltd. dmi.chassis.version: 1.0 dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr2.80:bd08/13/2019:svnMicro-StarInternationalCo.,Ltd.:pnMS-7B16:pvr1.0:rvnMicro-StarInternationalCo.,Ltd.:rnB360GAMINGPROCARBON(MS-7B16):rvr1.0:cvnMicro-StarInternationalCo.,Ltd.:ct3:cvr1.0: dmi.product.family: Default string dmi.product.name: MS-7B16 dmi.product.version: 1.0 dmi.sys.vendor: Micro-Star International Co., Ltd. version.compiz: compiz N/A version.libdrm2: libdrm2 2.4.99-1ubuntu1 version.libgl1-mesa-dri: libgl1-mesa-dri 19.2.1-1ubuntu1 version.libgl1-mesa-glx: libgl1-mesa-glx 19.2.1-1ubuntu1 version.xserver-xorg-core: xserver-xorg-core 2:1.20.5+git20191008-0ubuntu1 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.0.1-1ubuntu1 version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1852001/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp