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[keerthivasan <1990082@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

Description:
===========


As part of the openstack scheduling behaviour, able to observe this pattern where scheduling is not happening based on weight values, instead it is picking a random host from the list, thus violates the weighting behaviour

Configuration Nova:
===========

ram_weight_multiplier = 5.0
host_subset_size = 4

Steps To reproduce:
===========

I am testing this is in nova-23.2.0 ( Wallaby ) version based on
openstack-ansible

1) Create aggregate & make sure it has 5 hosts in it
2) Please make sure we are using instance extra spec for scheduling, to make sure vm's to use these 5 hosts from the aggregate
3) create 3 vm's in parallel
4) weighed_hosts obj list's all available weight hosts ( already sorted based on descending order ]
5) We are setting host_subset_size as 4 currently
6) 
         
        chosen_host = random.choice(weighed_subset)-----> [Since this is already sorted , why are we randomizing the behaviour rather than picking the first host ,weighed_subset[0] having higher weights]
        

Expected Results:
===========
1) Host with higher weights need's to be picked


Actual result
=============

1) It is picking based on random order from the sorted weighted list


Not sure the purpose of picking random host on the below one

https://github.com/openstack/nova/blob/stable/yoga/nova/scheduler/manager.py#L645

** Affects: nova
     Importance: Undecided
         Status: New


** Tags: wallaby-rc-potential

** Tags added: wallaby-rc-potential

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https://bugs.launchpad.net/bugs/1990082

Title:
  Scheduler is not choosing host based on higher weight value

Status in OpenStack Compute (nova):
  New

Bug description:
  Description:
  ===========

  
  As part of the openstack scheduling behaviour, able to observe this pattern where scheduling is not happening based on weight values, instead it is picking a random host from the list, thus violates the weighting behaviour

  Configuration Nova:
  ===========

  ram_weight_multiplier = 5.0
  host_subset_size = 4

  Steps To reproduce:
  ===========

  I am testing this is in nova-23.2.0 ( Wallaby ) version based on
  openstack-ansible

  1) Create aggregate & make sure it has 5 hosts in it
  2) Please make sure we are using instance extra spec for scheduling, to make sure vm's to use these 5 hosts from the aggregate
  3) create 3 vm's in parallel
  4) weighed_hosts obj list's all available weight hosts ( already sorted based on descending order ]
  5) We are setting host_subset_size as 4 currently
  6) 
           
          chosen_host = random.choice(weighed_subset)-----> [Since this is already sorted , why are we randomizing the behaviour rather than picking the first host ,weighed_subset[0] having higher weights]
          

  Expected Results:
  ===========
  1) Host with higher weights need's to be picked

  
  Actual result
  =============

  1) It is picking based on random order from the sorted weighted list

  
  Not sure the purpose of picking random host on the below one

  https://github.com/openstack/nova/blob/stable/yoga/nova/scheduler/manager.py#L645

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