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Bug 1828290

Summary: hugepages memory is reduced from max_scheduling_memory after hugepages property is removed from VM
Product: [oVirt] ovirt-engine Reporter: Polina <pagranat>
Component: BLL.VirtAssignee: Michal Skrivanek <michal.skrivanek>
Status: CLOSED NOTABUG QA Contact: meital avital <mavital>
Severity: high Docs Contact:
Priority: unspecified    
Version: 4.4.0CC: bugs
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Hardware: x86_64   
OS: Linux   
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Last Closed: 2020-04-27 14:55:45 UTC Type: Bug
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Description Polina 2020-04-27 14:07:22 UTC 
Created attachment 1682165 [details]
logs

Description of problem:hugepages memory is reduced from max_scheduling_memory even after hugepages configuration is removed from the VM


Version-Release number of selected component (if applicable):rhv-4.4.0-31 

How reproducible:100%

Steps to Reproduce:

pre-condition:

In Get https://{{host}}/ovirt-engine/api/hosts  response:
<max_scheduling_memory>33205256192</max_scheduling_memory>
on host:
/etc/vdsm/vdsm.conf
        [performance]
        use_dynamic_hugepages = true

On host: echo 4 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages

1. Configure VM (size 4096) with hugepages=1048576 (custom properties)
2. Run the VM.
   max_scheduling_memory reduces accordingly <max_scheduling_memory>28801236992</max_scheduling_memory>
3. Shutdown the VM - max_scheduling_memory increases back to 33205256192.
4. Configure the same VM (size 4096) with no hugepages. Re-start The VM.

Actual results: 
       max_scheduling_memory reduces as even the hugepages are configured <max_scheduling_memory>28801236992</max_scheduling_memory> 

Expected: max_scheduling_memory must reduce only by size of the VM 
          <max_scheduling_memory>33205252096</max_scheduling_memory>, where 33205252096 = 33205256192 - 4096(vm size)


in the attached engine.log the test starts at 2020-04-27 16:51:05
Comment 1 Polina 2020-04-27 14:55:45 UTC 
closed according to the https://bugzilla.redhat.com/show_bug.cgi?id=1804046#c24