Let me try a wild guess, it looks like buffer fragmentation related to network/ssh/openZFS. The software might desperately try to defragment many small spaces and that would explain the 100% CPU load during the low speed transfers. If the defragmentation happens in the kernel, it also might explain, why the CPU frequency is not increased. Note that only Conky records that 100% CPU load, while the task manager does not notice anything and has the load below 30% all the time.
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to zfs-linux in Ubuntu. https://bugs.launchpad.net/bugs/1969281 Title: Very slow reception of incremental OpenZFS backup Status in zfs-linux package in Ubuntu: New Bug description: Since OpenZFS the reception of incremental backups over ssh are very slow; FreeBSD 13.0 with OpenZFS running on a 2003 Pentium 4 HT 3.0GHz (1.5GB DDR) is faster than Ubuntu 21.10/22.04 with OpenZFS running on my laptop with an i5-2520m (8GB DDR3). FreeBSD runs at 21 MiB/s with a 10% variance; The limit is caused by the load on a P4 CPU thread of >90%; For Ubuntu the transfer speed is between 90 MiB/S and periods of seconds long with 0 MiB/s. A lot of time the transfer speed is in the single digit numbers. The problems occur when one or two of the four i5 cpu threads run at 100%, while the CPU clock remains at 0.83 GHz. So it looks like an integration issue between OpenZFS and the Linux kernel. ProblemType: Bug DistroRelease: Ubuntu 22.04 Package: zfsutils-linux 2.1.2-1ubuntu3 ProcVersionSignature: Ubuntu 5.15.0-25.25-generic 5.15.30 Uname: Linux 5.15.0-25-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu82 Architecture: amd64 CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Sat Apr 16 14:49:10 2022 InstallationDate: Installed on 2021-10-30 (168 days ago) InstallationMedia: Ubuntu 21.10 "Impish Indri" - Release amd64 (20211012) SourcePackage: zfs-linux UpgradeStatus: No upgrade log present (probably fresh install) modified.conffile..etc.sudoers.d.zfs: [inaccessible: [Errno 13] Permission denied: '/etc/sudoers.d/zfs'] To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1969281/+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
