yahoo-eng-team team mailing list archive

[Sylvain Bauza <sbauza@xxxxxxx>]

Public bug reported:

When creating the allocation for the instance, we lookup the flavor to
know the disk sizes for root, ephemeral and gb and we basically sum
them.

https://github.com/openstack/nova/blob/7d04c78c1e2c26125eff5b1a8543b1ac5d027107/nova/scheduler/client/report.py#L129-L131

Unfortunately, since both root and ephemeral size are expressed in GB
while swap is expressed in MB, the sum is not good.

See how the DiskFilter works for accounting resources :
https://github.com/openstack/nova/blob/3cafa7f5bd0775b8ba49080226c03f8a91468d7d/nova/scheduler/filters/disk_filter.py#L36-L38

We should change the logic to ceil to the next GB if modulo(root +
ephemeral * 1024 + swap / 1024) is not rounded to 0 since we want to
count allocations as the Inventory only counts by GB.

That's suboptimal and a long-term solution would be to report
inventories in bytes (as the smallest attribute) but that's a big change
so probably requiring a BP.

** Affects: nova
     Importance: High
         Status: Confirmed


** Tags: compute low-hanging-fruit placement resource-tracker

** Description changed:

  When creating the allocation for the instance, we lookup the flavor to
  know the disk sizes for root, ephemeral and gb and we basically sum
  them.
  
  https://github.com/openstack/nova/blob/7d04c78c1e2c26125eff5b1a8543b1ac5d027107/nova/scheduler/client/report.py#L129-L131
  
  Unfortunately, since both root and ephemeral size are expressed in GB
  while swap is expressed in MB, the sum is not good.
  
  See how the DiskFilter works for accounting resources :
  https://github.com/openstack/nova/blob/3cafa7f5bd0775b8ba49080226c03f8a91468d7d/nova/scheduler/filters/disk_filter.py#L36-L38
  
  We should change the logic to ceil to the next GB if modulo(root +
  ephemeral * 1024 + swap / 1024) is not rounded to 0 since we want to
  count allocations as the Inventory only counts by GB.
  
  That's suboptimal and a long-term solution would be to report
- inventories in MB but that's a big change so probably requiring a BP.
+ inventories in bytes (as the smallest attribute) but that's a big change
+ so probably requiring a BP.

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https://bugs.launchpad.net/bugs/1659266

Title:
  Disk allocation for instance is not good with swap

Status in OpenStack Compute (nova):
  Confirmed

Bug description:
  When creating the allocation for the instance, we lookup the flavor to
  know the disk sizes for root, ephemeral and gb and we basically sum
  them.

  https://github.com/openstack/nova/blob/7d04c78c1e2c26125eff5b1a8543b1ac5d027107/nova/scheduler/client/report.py#L129-L131

  Unfortunately, since both root and ephemeral size are expressed in GB
  while swap is expressed in MB, the sum is not good.

  See how the DiskFilter works for accounting resources :
  https://github.com/openstack/nova/blob/3cafa7f5bd0775b8ba49080226c03f8a91468d7d/nova/scheduler/filters/disk_filter.py#L36-L38

  We should change the logic to ceil to the next GB if modulo(root +
  ephemeral * 1024 + swap / 1024) is not rounded to 0 since we want to
  count allocations as the Inventory only counts by GB.

  That's suboptimal and a long-term solution would be to report
  inventories in bytes (as the smallest attribute) but that's a big
  change so probably requiring a BP.

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