This bug was fixed in the package linux - 5.4.0-42.46
---------------
linux (5.4.0-42.46) focal; urgency=medium
* focal/linux: 5.4.0-42.46 -proposed tracker (LP: #1887069)
* linux 4.15.0-109-generic network DoS regression vs -108 (LP: #1886668)
- SAUCE: Revert "netprio_cgroup: Fix unlimited memory leak of v2 cgroups"
linux (5.4.0-41.45) focal; urgency=medium
* focal/linux: 5.4.0-41.45 -proposed tracker (LP: #1885855)
* Packaging resync (LP: #1786013)
- update dkms package versions
* CVE-2019-19642
- kernel/relay.c: handle alloc_percpu returning NULL in relay_open
* CVE-2019-16089
- SAUCE: nbd_genl_status: null check for nla_nest_start
* CVE-2020-11935
- aufs: do not call i_readcount_inc()
* ip_defrag.sh in net from ubuntu_kernel_selftests failed with 5.0 / 5.3 / 5.4
kernel (LP: #1826848)
- selftests: net: ip_defrag: ignore EPERM
* Update lockdown patches (LP: #1884159)
- SAUCE: acpi: disallow loading configfs acpi tables when locked down
* seccomp_bpf fails on powerpc (LP: #1885757)
- SAUCE: selftests/seccomp: fix ptrace tests on powerpc
* Introduce the new NVIDIA 418-server and 440-server series, and update the
current NVIDIA drivers (LP: #1881137)
- [packaging] add signed modules for the 418-server and the 440-server
flavours
-- Khalid Elmously <[email protected]> Thu, 09 Jul 2020
19:50:26 -0400
** Changed in: linux (Ubuntu)
Status: In Progress => Fix Released
** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-16089
** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-19642
** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-11935
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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:
Fix Released
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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