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[Matt Riedemann <mriedem.os@xxxxxxxxx>]

** Also affects: nova/pike
   Importance: Undecided
       Status: New

** Changed in: nova/pike
       Status: New => In Progress

** Changed in: nova/pike
     Assignee: (unassigned) => sahid (sahid-ferdjaoui)

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https://bugs.launchpad.net/bugs/1735321

Title:
   Bug in log output in hardware.py "Not enough available memory to
  schedule instance" prints full memory instead of available memory

Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) pike series:
  In Progress

Bug description:
  Description of problem:
  Bug in log output in hardware.py "Not enough available memory to schedule instance" prints full memory instead of available memory

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

  
  Additional info:

  When nova fails scheduling, it will print:
  ~~~
  2017-11-29 10:50:16.904 325123 DEBUG nova.virt.hardware [req-b62c53d2-13db-4fac-a125-409b4f046418 8f883df20fce46dbef3ce634610c51be53b87e658359f05b7eba1062ce7e5d8b 5b54e36678a542d899f1ff62268fc25a - - -] Not enough available memory to schedule instance. Oversubscription is not possible with pinned instances. Required: 32768, actual: 65406 _numa_fit_instance_cell_with_pinning /usr/lib/python2.7/site-packages/nova/virt/hardware.py:845
  2017-11-29 10:50:16.904 325123 DEBUG oslo_concurrency.lockutils [req-b62c53d2-13db-4fac-a125-409b4f046418 8f883df20fce46dbef3ce634610c51be53b87e658359f05b7eba1062ce7e5d8b 5b54e36678a542d899f1ff62268fc25a - - -] Lock "compute_resources" released by "nova.compute.resource_tracker.instance_claim" :: held 0.021s inner /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:282
  2017-11-29 10:50:16.905 325123 DEBUG nova.compute.manager [req-b62c53d2-13db-4fac-a125-409b4f046418 8f883df20fce46dbef3ce634610c51be53b87e658359f05b7eba1062ce7e5d8b 5b54e36678a542d899f1ff62268fc25a - - -] [instance: 86cc16bd-5f51-402b-aa03-01ab0c3ffaf4] Insufficient compute resources: Requested instance NUMA topology cannot fit the given host NUMA topology. _build_and_run_instance /usr/lib/python2.7/site-packages/nova/compute/manager.py:1934
  ~~~

  This of course looks very confusing (we need 32 GB, we have 64, so why
  is this failing?).

  The problem here is the log output, which is flawed --- /usr/lib/python2.7/site-packages/nova/virt/hardware.py:
  ~~~
      840     if host_cell.avail_memory < instance_cell.memory:
      841         LOG.debug('Not enough available memory to schedule instance. '
      842                   'Oversubscription is not possible with pinned instances. '
      843                   'Required: %(required)s, actual: %(actual)s',
      844                   {'required': instance_cell.memory,
      845                    'actual': host_cell.memory})
      846         return
  ~~~

  This should be:
  ~~~
      840     if host_cell.avail_memory < instance_cell.memory:
      841         LOG.debug('Not enough available memory to schedule instance. '
      842                   'Oversubscription is not possible with pinned instances. '
      843                   'Required: %(required)s, actual: %(actual)s',
      844                   {'required': instance_cell.memory,
      845                    'actual': host_cell.avail_memory})
      846         return
  ~~~

  Or even better:
  ~~~
      840     if host_cell.avail_memory < instance_cell.memory:
      841         LOG.debug('Not enough available memory to schedule instance. '
      842                   'Oversubscription is not possible with pinned instances. '
      843                   'Required: %(required)s, actual: %(actual)s, total: %(total)s',
      844                   {'required': instance_cell.memory,
      845                    'actual': host_cell.avail_memory,
      846                    'total': host_cell.memory})
      847         return
  ~~~

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