All autopkgtests for the newly accepted linux-oracle-5.4 
(5.4.0-1019.19~18.04.1) for bionic have finished running.
The following regressions have been reported in tests triggered by the package:

zfs-linux/unknown (armhf)


Please visit the excuses page listed below and investigate the failures, 
proceeding afterwards as per the StableReleaseUpdates policy regarding 
autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/bionic/update_excuses.html#linux-oracle-5.4

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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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:
  Fix Committed
Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Focal:
  Fix Released

Bug description:
  SRU Justification:
  ==================

  [Impact]

  * PSI is enabled by default for all architectures in Ubuntu.

  * On s390x this leads to performance degradations on popular workloads
  like web serving (nginx).

  [Fix]

  * Leave 'CONFIG_PSI=y', but change 'CONFIG_PSI_DEFAULT_DISABLED=n' to
  'CONFIG_PSI_DEFAULT_DISABLED=y'

  [Test Case]

  * Measure the overhead with 'CONFIG_PSI_DEFAULT_DISABLED=n' and
  'CONFIG_PSI_DEFAULT_DISABLED=y' on the same environment with nginx.

  [Regression Potential]

  * The regression potential can be considered as moderate, since PSI
  (Pressure stall information tracking),

  * since PSI is just used to collect CPU overcommitted, memory and IO
  metrics.

  * And it can be enabled again with the kernel argument.
  __________

  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.

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