Bug 1614001

Summary: Description of Memory Utilization panel on Host dashboard is misleading
Product: [Red Hat Storage] Red Hat Gluster Storage Reporter: Martin Bukatovic <mbukatov>
Component: web-admin-tendrl-monitoring-integrationAssignee: gowtham <gshanmug>
Status: CLOSED ERRATA QA Contact: Elena Bondarenko <ebondare>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: rhgs-3.4CC: apaladug, ebondare, julim, mbukatov, nthomas, rhinduja, rhs-bugs, sankarshan
Target Milestone: ---Keywords: ZStream
Target Release: RHGS 3.4.z Batch Update 1   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: tendrl-monitoring-integration-1.6.3-13.el7rhgs Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2018-10-31 08:45:18 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:
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Description Flags
screenshot of the Memory Utilization description none

Description Martin Bukatovic 2018-08-08 19:23:07 UTC 
Description of problem
======================

Description of Total should not be there because such data are not reported in the chart. This description is also misleading (sheer total usually means total memory installed, not just total memory used). Moreover description of Used
field actually uses total in it's usual meaning.

Other problem is that it's not clear if Cached field include Slab Reclaimable
memory?

Version-Release number of selected component
============================================

tendrl-monitoring-integration-1.6.3-7.el7rhgs.noarch

Steps to Reproduce
==================

1. Instal RHGS WA using tendrl-ansible
2. Import Trusted storage pool with at least one volume
3. Go to Host dashboard and check description of Memory Utilization panel

Actual results
==============

The description states:

~~~
The Memory Utilization panel displays memory utilization percentage for a given host that includes buffers and caches used by the kernel over a period of time.

Buffered: Amount of memory used for buffering, mostly for I/O operations.
Cached: Memory used for caching disk data for reads, memory-mapped files or tmpfs data.
Slab Rec: Amount of reclaimable memory used for slab kernel allocations.
Slab Unrecl: Amount of unreclaimable memory used for slab kernel allocations.
Used: Amount of memory used, calculated as Total - Free (Unused Memory) - Buffered - Cache
Total: Total memory used

The memory utilization threshold is set to 80%. Reaching or exceeding this value displays an orange horizontal line indicating high memory usage.
~~~

Description of Total:

 * should not be there because such data are not reported in the chart
 * doesn't follow usual meaning ( total usually means total memory installed,
   not just total memory used)

Description of Used:

 * actually uses total in it's usual meaning, not the definition from the
   description

Description of Cached:

 * it's not clear if it includes Slab Reclaimable memory

Expected results
================

There are no conflicts with usual meaning of the terms or with the description
itself.
Comment 1 Martin Bukatovic 2018-08-08 19:25:23 UTC 
Created attachment 1474483 [details]
screenshot of the Memory Utilization description
Comment 3 gowtham 2018-09-05 15:26:37 UTC 
Proposed Description:

The Memory Utilization panel displays memory utilization percentage for a given host that includes buffers and caches used by the kernel over a period of time.

Buffered: Amount of memory used for buffering, mostly for I/O operations.
Cached: Memory used for caching disk data for reads, memory-mapped files or tmpfs data.
Slab Rec: Amount of reclaimable memory used for slab kernel allocations.
Slab Unrecl: Amount of unreclaimable memory used for slab kernel allocations.
Used: Amount of memory used, calculated as Total memory used - Free (Unused Memory) - Buffered - Cache

The memory utilization threshold is set to 80%. Reaching or exceeding this value displays an orange horizontal line indicating high memory usage.



Note: cached memory does not include SReclaimable, what I found is 

Term Cache represent "page cache" 

looks like page cache and slabs are different
Comment 9 Nishanth Thomas 2018-09-10 16:24:18 UTC 
ack this bug based on https://bugzilla.redhat.com/show_bug.cgi?id=1614001#c3
Comment 10 Martin Bukatovic 2018-09-11 12:26:36 UTC 
Providing qe ack based on comment 3, noting that:

 * this BZ is about the description of the panel only
 * since cached memory does not include SReclaimable (see comment 3), it's not
   necessary to point this out in the description
 * we need to remove description of Total

Also I noticed a typo in the proposed update of the description, it defines
"Used" as:

> Amount of memory used, calculated as
> Total memory used - Free (Unused Memory) - Buffered - Cache

which seems incorrect ("used" is defined as "total used" minus something), we
should keep that as it was:

> Amount of memory used, calculated as
> Total - Free (Unused Memory) - Buffered - Cache
Comment 12 gowtham 2018-09-11 12:46:18 UTC 
As per the last comment, I modified a description like: 

The Memory Utilization panel displays memory utilization percentage for a given host that includes buffers and caches used by the kernel over a period of time.

Buffered: Amount of memory used for buffering, mostly for I/O operations.
Cached: Memory used for caching disk data for reads, memory-mapped files or tmpfs data.
Slab Rec: Amount of reclaimable memory used for slab kernel allocations.
Slab Unrecl: Amount of unreclaimable memory used for slab kernel allocations.
Used: Amount of memory used, calculated as Total - Free (Unused Memory) - Buffered - Cache

The memory utilization threshold is set to 80%. Reaching or exceeding this value displays an orange horizontal line indicating high memory usage.
Comment 13 gowtham 2018-09-11 13:00:09 UTC 
PR is under review: https://github.com/Tendrl/monitoring-integration/pull/569
Comment 15 Elena Bondarenko 2018-09-25 12:43:26 UTC 
Description of Memory Utilization panel is exactly the way it was described in Comment 12.
Comment 17 errata-xmlrpc 2018-10-31 08:45:18 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, 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/RHBA-2018:3427