Bug 2178863

Summary: mpstat intermittently shows incorrect CPU usage on ALL CPU field for "iowait"
Product: Red Hat Enterprise Linux 8 Reporter: Christian Horn <chorn>
Component: sysstatAssignee: Lukáš Zaoral <lzaoral>
Status: CLOSED ERRATA QA Contact: Radka Brychtova <rskvaril>
Severity: low Docs Contact:
Priority: unspecified    
Version: 8.4CC: masanari.iida, rskvaril
Target Milestone: rcKeywords: Triaged
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: sysstat-11.7.3-10.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 2178865 (view as bug list) Environment:
Last Closed: 2023-11-14 15:34:59 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2178865    
Deadline: 2023-03-27   

Description Christian Horn 2023-03-16 01:06:38 UTC 
Description of problem:
mpstat on intermittently shows incorrect CPU usage on ALL CPU field for "iowait"

Version-Release number of selected component (if applicable):
All versions affected, affected customer here used sysstat-11.7.3-5.el8

How reproducible:
not easily

Steps to Reproduce:
1. On a bugger system, i.e. 32 cores, execute mpstat, for example "mpstat  -P ALL 1 1" or "mpstat  -P ALL 1 3600"

Actual results: 
Total CPU usage (%iowait) is 97.10%.
01:17:04 AM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
01:17:05 AM  all    0.00    0.00    0.01   _97.10_    0.00    0.00    0.00    0.00    0.00    2.88
01:17:05 AM   17    0.00    0.00    0.00   _99.91_    0.00    0.00    0.00    0.00    0.00    0.09

Expected results: 
Total CPU usage (%iowait) should be a value which is divided by 32, because the system has 32 CPUs.
01:17:04 AM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
01:17:05 AM  all    0.00    0.00    0.01  _3.12_    0.00    0.00    0.00    0.00    0.00    2.88
01:17:05 AM   17    0.00    0.00    0.00  _99.91_   0.00    0.00    0.00    0.00    0.00    0.09

Additional info:
- Issue exists also in upstream
- a build of mpstat with the following commit was reported to fix
  the issue for the customer:
  https://github.com/sysstat/sysstat/commit/1f5949d4a6fcb33065dbb1d509f356db039998ed

So, requesting this commit into RHEL.
Workaround exists, Performance Co-Pilot (PCP) provides independent code which
gathers metrics and provides with "pcp mpstat" an independent client of similar
output, which does not show the issue.
Comment 2 Lukáš Zaoral 2023-03-16 12:03:16 UTC 
CentOS Stream 8 MR: https://gitlab.com/redhat/centos-stream/rpms/sysstat/-/merge_requests/7
Comment 11 errata-xmlrpc 2023-11-14 15:34:59 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: sysstat security and bug fix update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2023:7010