Following this thread I had the same issue, running stock 16.04 (xenial) with kernel 4.4.0-38. I have upgraded the kernel to 4.8.10-040810 and the end result is the same but symptoms are a bit different:
note: 1GB of RAM, no swap at all (old kernel) with 50% of RAM in buffers / cache, kswapd0 took all the CPU it could (~75%). iostat was pretty much at 0% utilisation. server ground to a halt immediately when free ram expired without ever "eating into" the buffers / cache. (new kernel) again, with 50% of RAM in buffers / cache, kswapd0 no longer takes 100% CPU, but it still emerges to the top of the list in top as it still manages to take more then the other processes. For a difference, now ~75% cpu processes are *WA*iting. A second difference is that now, after free ram is consumed, for a while buffers / cache are also being reduced in favour of the RAM hungry app. However, even this goes only down to about 40 - 43% or RAM being used by buffers / cache. Hopefully this is making at least some sense. -- 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/1518457 Title: kswapd0 100% CPU usage Status in Linux: Unknown Status in linux package in Ubuntu: Invalid Status in linux source package in Xenial: Fix Released Status in linux source package in Yakkety: Fix Released Bug description: As per bug 721896 and various others: I'm on an AWS t2.micro instance (Xeon E5-2670, 991MiB of memory). Occasionally (about once a day), kswapd0 falls into a busy loop and spins on 100% CPU usage indefinitely. This can be provoked by copying/writing large files (e.g. dding a 256MB file), but it happens occasionally otherwise. System memory usage (not including buffers/caches) currently sits at 36%, which is typical[1]. Initially I had no swap space configured; I've since tried enabling a 256MB swap file, but the problem continues to occur and no swap space is used. The system can be recovered with `echo 1 > /proc/sys/vm/drop_caches`. Happy to provide further information/take further debugging actions. [1] Full output from `free`: total used free shared buffers cached Mem: 1014936 483448 531488 28556 9756 112700 -/+ buffers/cache: 360992 653944 Swap: 262140 0 262140 ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: linux-image-4.2.0-18-generic 4.2.0-18.22 ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3 Uname: Linux 4.2.0-18-generic x86_64 AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Nov 19 19:40 seq crw-rw---- 1 root audio 116, 33 Nov 19 19:40 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.19.1-0ubuntu5 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CRDA: N/A Date: Fri Nov 20 20:44:30 2015 Ec2AMI: ami-1c552a76 Ec2AMIManifest: (unknown) Ec2AvailabilityZone: us-east-1d Ec2InstanceType: t2.micro Ec2Kernel: unavailable Ec2Ramdisk: unavailable IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig' Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize libusb: -99 MachineType: Xen HVM domU PciMultimedia: ProcEnviron: TERM=screen PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 xen ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-18-generic root=UUID=35bc01f4-4602-4823-976e-508edef899df ro console=tty1 console=ttyS0 net.ifnames=0 RelatedPackageVersions: linux-restricted-modules-4.2.0-18-generic N/A linux-backports-modules-4.2.0-18-generic N/A linux-firmware N/A RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev' UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 05/06/2015 dmi.bios.vendor: Xen dmi.bios.version: 4.2.amazon dmi.chassis.type: 1 dmi.chassis.vendor: Xen dmi.modalias: dmi:bvnXen:bvr4.2.amazon:bd05/06/2015:svnXen:pnHVMdomU:pvr4.2.amazon:cvnXen:ct1:cvr: dmi.product.name: HVM domU dmi.product.version: 4.2.amazon dmi.sys.vendor: Xen To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1518457/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
