Is there an estimate as to when you are likely to pick up this fix? -- 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/1848212
Title: Optane PM access times are much longer than they should be Status in linux package in Ubuntu: Confirmed Bug description: I have 4 128GB Optane DC Persistent Memory devices in my server, assigned to AppDirect access (i.e., accessed via memory-mapping at the cache line level), and have run into a severe performance issue with the latest kernel 5.0.0-31. I realize that not many people have this storage type as yet, but it is becoming increasingly important in the server world, so I think this bug is pretty important. Bug details: When running with kernel 5.0.0-29, write access times to the Optane PM devices are in the sub-microsecond range, as they should be. When running with kernel 5.0.0-31, write access times are much slower, averaging in the 30 microsecond range, until a large number of writes (see below) have been executed. Then they return to normal speed. My application is a hash table implementation optimized for the Optane PM devices (see webpage at www.threemisses.com). Since it is a hash table, it has very poor locality of reference, and is filled "randomly", so I don't know exactly what the sequence of writes is. However, I can say that the speed is very slow until the fill ratio of the hash table is about 50%, then it returns to the normal sub- microsecond range. ProblemType: Bug DistroRelease: Ubuntu 19.04 Package: linux-image-5.0.0-31-generic 5.0.0-31.33 ProcVersionSignature: Ubuntu 5.0.0-31.33-generic 5.0.21 Uname: Linux 5.0.0-31-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia ApportVersion: 2.20.10-0ubuntu27.1 Architecture: amd64 Date: Tue Oct 15 09:01:06 2019 InstallationDate: Installed on 2019-09-02 (42 days ago) InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416) IwConfig: lo no wireless extensions. eno0 no wireless extensions. enp181s0f1 no wireless extensions. MachineType: Supermicro SYS-7039A-I ProcEnviron: LD_LIBRARY_PATH=<set> TERM=xterm-256color PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 EFI VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.0.0-31-generic root=UUID=3239f211-86a3-44bb-8251-62037ebea848 ro transparent_hugepage=always quiet splash nomodeset vt.handoff=1 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-5.0.0-31-generic N/A linux-backports-modules-5.0.0-31-generic N/A linux-firmware 1.178.3 RfKill: SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 03/06/2019 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 3.0a dmi.board.asset.tag: ZM193S000653 dmi.board.name: X11DAi-N dmi.board.vendor: Supermicro dmi.board.version: 1.02 dmi.chassis.asset.tag: Default string dmi.chassis.type: 1 dmi.chassis.vendor: Supermicro dmi.chassis.version: 123456789 dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr3.0a:bd03/06/2019:svnSupermicro:pnSYS-7039A-I:pvr123456789:rvnSupermicro:rnX11DAi-N:rvr1.02:cvnSupermicro:ct1:cvr123456789: dmi.product.family: SMC X11 dmi.product.name: SYS-7039A-I dmi.product.sku: 097A15D9 dmi.product.version: 123456789 dmi.sys.vendor: Supermicro To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1848212/+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
