** Summary changed: - [UBUNTU 20.04] Overhead introduced by PSI + [UBUNTU 20.04] PSI generated overhead on s390x
** Summary changed: - [UBUNTU 20.04] PSI generated overhead on s390x + [UBUNTU 20.04] PSI generates overhead on s390x -- 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/1876044 Title: [UBUNTU 20.04] PSI generates overhead on s390x Status in Ubuntu on IBM z Systems: Triaged Status in linux package in Ubuntu: New Bug description: PSI is always enabled in Ubuntu 20.04. For a test system with 72 guests on 8 cores running a nginx workload this created an overhead of ~1%. Can we change this back to CONFIG_PSI=y CONFIG_PSI_DEFAULT_DISABLED=y so that by default the overhead is not there but for debugging or if needed it can still be enabled via kernel parm? Maybe there has been a reason for this - so feel free to discuss. ---uname output--- Linux t35lp76 5.4.0-26-generic #30-Ubuntu SMP Mon Apr 20 16:57:22 UTC 2020 s390x s390x s390x GNU/Linux Machine Type = All s390x architecture ---Debugger--- A debugger is not configured ---Steps to Reproduce--- root@t35lp76:/boot# grep PSI config-5.4.0-26-generic CONFIG_PSI=y # CONFIG_PSI_DEFAULT_DISABLED is not set Stack trace output: no Oops output: no System Dump Info: The system is not configured to capture a system dump. *Additional Instructions for epasch@de,ibm.com: -Attach sysctl -a output output to the bug. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1876044/+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
