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Created attachment 990139 [details]
screenshots.tar.gz

Description of problem:

Version-Release number of selected component (if applicable):
kernel-3.10.0-229.el7
gnome-system-monitor-3.8.2.1-6.el7
libgtop2-2.28.4-7.el7

How reproducible:
always

Steps to Reproduce:
1. Open gnome-system-monitor
2. Go to Resources tab
3. Watch the Memory and Swap History
4. Open terminal and run: free -mh

Actual results: Utilities display different value of used memory. 
                e.g. in ppc64: 999MB <> 1.6GiB (1.717 GB) 

Expected results: Swap and RAM usage should more or less correspond in both utilities.

Additional info: Screenshots are packaged in attachment.

This discrepancy is not unexpected, given how libgtop determines the amount of free memory. It does so by parsing /proc/meminfo, followed by subtracting Buffers, Cached and MemFree from MemTotal.

The free utility works differently, because it includes the Slab field in its used memory calculation (or uses MemAvailable).

There is an upstream bug report (with a patch) to change the reporting in libgtop to use the MemAvailable field present in kernel 3.14 and above, which would make the libgtop output similar to the free output.

This will be fixed by the GNOME rebase for RHEL 7.4.

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, 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/RHEA-2017:2305