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Bug 2230431 - The `sar -B` reports '%vmeff' beyond 100
Summary: The `sar -B` reports '%vmeff' beyond 100
Keywords:
Status: CLOSED MIGRATED
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: sysstat
Version: 9.0
Hardware: x86_64
OS: Unspecified
unspecified
low
Target Milestone: rc
: ---
Assignee: Lukáš Zaoral
QA Contact: qe-baseos-daemons
Šárka Jana
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2023-08-09 12:29 UTC by Abdul Rehman Quadri
Modified: 2023-10-06 16:36 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Known Issue
Doc Text:
.The `%vmeff` metric from the `sysstat` package displays incorrect values The `sysstat` package provides the `%vmeff` metric to measure the page reclaim efficiency. The values of the `%vmeff` column returned by the `sar -B` command are incorrect because `sysstat` does not parse all relevant `/proc/vmstat` values provided by later kernel versions. To work around this problem, you can calculate the `%vmeff` value manually from the `/proc/vmstat` file. For details, see link:https://access.redhat.com/solutions/7027076[Why the `sar(1)` tool reports `%vmeff` values beyond 100 % in RHEL 8 and RHEL 9?]
Clone Of:
Environment:
Last Closed: 2023-10-06 16:36:13 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker   RHEL-12009 0 None Migrated None 2023-10-06 16:36:09 UTC
Red Hat Issue Tracker RHELPLAN-165085 0 None None None 2023-08-09 12:29:56 UTC

Description Abdul Rehman Quadri 2023-08-09 12:29:00 UTC 
Description of problem:
The `sar -B` commands report the paging statistics where the output
includes '%vmeff' column.
The `%vmeff` as per the man page is [pgsteal / pgscan].

Version-Release number of selected component (if applicable):
sysstat-12.5.4-5.el9.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Stress the system for memory utilization so that the cache is reclaimed & swapping occurs.
2. sar -B
3. And look for the `%vmeff` column.

Actual result:
# sar -B 1
Linux 5.14.0-284.25.1.el9_2.x86_64 (9rhel) 	08/09/2023 	_x86_64_	(1 CPU)

04:36:26 PM  pgpgin/s pgpgout/s   fault/s  majflt/s  pgfree/s pgscank/s pgscand/s pgsteal/s    %vmeff
04:36:27 PM      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
04:36:28 PM      0.00      0.00      0.00      0.00      4.00      0.00      0.00      0.00      0.00
04:36:29 PM      0.00      0.00      0.00      0.00      1.00      0.00      0.00      0.00      0.00
04:36:30 PM    491.09 105586.14  60935.64      4.95  57935.64 239636.63   9034.65  94788.12     38.12
04:36:31 PM  12310.00 538256.00  80468.00    133.00  92348.00 204523.00  43644.00 164542.00     66.30
04:36:32 PM   1031.67 167920.00  74993.75     13.33  79612.08 172162.08  15215.00 149747.50     79.92
04:36:34 PM    994.29 499363.81 122150.48     19.05 138315.24 319519.05  70208.57 251845.71     64.62
04:36:35 PM  13865.26 254842.11  21938.95    441.05  48472.63 131057.89  11048.42  81572.63     57.40
04:36:36 PM 153948.62 129625.69  43133.03   4892.66  45727.52 109327.52      0.00  69844.04     63.89
04:36:37 PM  72123.08      9.89  19817.58   2248.35  17915.38  10175.82      0.00  20351.65    200.00  <<-----
04:36:38 PM  29152.00      0.00   8227.00    919.00   7413.00   7411.00      0.00  14806.00    199.78  <<-----
04:36:39 PM 105044.25 205497.35  29342.48   3339.82  37755.75 151597.35      0.00  62493.81     41.22
04:36:40 PM 107365.52      0.00  29221.84   3340.23  19342.53  19228.74      0.00  38340.23    199.39  <<----- 
04:36:41 PM 399295.05 348940.59 111702.97  12735.64 106972.28 246384.16      0.00 200459.41     81.36
04:36:42 PM 322668.00 339464.00  89742.00  10247.00  93473.00 273802.00      0.00 170922.00     62.43
04:36:43 PM 408888.00 380136.00 113442.00  12926.00 105087.00 276010.00      0.00 194792.00     70.57
04:36:44 PM 390824.00 389380.00 108543.00  12304.00 107732.00 311288.00      0.00 198284.00     63.70
04:36:46 PM 109600.00 248129.17  30189.06   3431.77  45426.56 148714.06      0.00  76365.62     51.35
04:36:47 PM  70936.00      0.00  19666.00   2239.00     31.00      0.00      0.00     44.00      0.00
04:36:48 PM 108696.00      0.00  30310.00   3477.00  24087.00  24083.00      0.00  48148.00    199.93  <<-----


Expected result:
The value of %vmeff should be <=100%


Additional info:
The Bugzilla has already been raised for RHEL 8[1] and it was identified that the changes in the /proc/vmstat fields caused this issue. The issue has been raised to upstream[2].

Raising this Bugzilla to track for RHEL9.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=2228949
[2] https://github.com/sysstat/sysstat/issues/343#issuecomment-1667640798
Comment 3 RHEL Program Management 2023-10-06 16:35:51 UTC 
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.
Comment 4 RHEL Program Management 2023-10-06 16:36:13 UTC 
This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.

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