Public bug reported:
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.
** Affects: ubuntu-z-systems
Importance: Medium
Assignee: Skipper Bug Screeners (skipper-screen-team)
Status: Triaged
** Affects: linux (Ubuntu)
Importance: Undecided
Assignee: Canonical Kernel Team (canonical-kernel-team)
Status: New
** Tags: architecture-s3903164 bugnameltc-185697 severity-medium
targetmilestone-inin---
** Tags added: architecture-s3903164 bugnameltc-185697 severity-medium
targetmilestone-inin---
** Changed in: ubuntu
Assignee: (unassigned) => Skipper Bug Screeners (skipper-screen-team)
** Package changed: ubuntu => linux (Ubuntu)
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https://bugs.launchpad.net/bugs/1876044
Title:
[UBUNTU 20.04] Overhead introduced by PSI
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