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0e1f616
(Get the code!)
Reposting comment because it's formatted horribly (if this doesn't work, sorry):
PiN == provisioned in Nova, PiI == provisioned in Ironic.
How it used to work:
Broke PiN PiI UsedMem AvailMem Reported
Y Y Y 100 100 0
Y Y N 100 0 -100
Y N Y 0 100 100
Y N N 0 0 0
N Y Y 100 100 0
N Y N 100 100 0
N N Y 0 100 100
N N N 0 100 100
These changes were made:
https:/
https:/
How it works now:
Broke PiN PiI UsedMem AvailMem Reported
Y Y Y 100 0 -100 -> 0
Y Y N 100 0 -100 -> 0
Y N Y 0 0 0
Y N N 0 0 0
N Y Y 100 0 -100 -> 0
N Y N 100 100 0
N N Y 0 0 0
N N N 0 100 100
Basically, only schedule to an Ironic node if it's not broken and
neither Nova or Ironic have it marked as provisioned.
If negative values are allowed, these cases would be considered
oversubscriptions, but they are not. Allowing negative RAM causes
confusion, and misrepresents available memory (controlled by the
hypervisor / node). This can lead to subtle bugs when the memory
is not available and oversubscribing is allowed. One example is
the possiblity of scheduling to a node that has no available
memory. Another example, negative memory is substractred from
available memory in cells reporting causing builds to fail even
though capacity is available.
At the time of this writing, I'm not certain to what level
oversubscriptions are broken since the available memory limit is
stored at a higher value using the ram allocation factor. It will
take a bit more digging before I fully grok the impact of
disallowing negative values here.
One potential way to solve for both cases is to rework the filters
to use the ram_allocation_
of increasing the available memory limit
(https:/
I believe this would eliminate the need for negative values and
still allow for oversubscriptions. I can go down this path if it
makes sense, but probably good to have a conversation first.