Comment 0 for bug 1876044

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.