overcommit ratios should not be able to set to negative value

[vu tran]

Currently the three overcommit ratios: ram_allocation_ratio, cpu_allocation_ratio, and disk_allocation_ratio can be set to negative values.

Nova scheduler filters (e.g. CoreFilter) will use these ratios to calculate free_vcpus/free_ram_mb/usable_disk_mb (which is negative) and therefore scheduler filters will eventually filter out node which has negative overcommit ratio.

It makes more sense that these 3 ratios values should not be able to set to negative values. If any of these ratios is negative then nova-compute service should fail to start.

Step to reproduce on devstack:

* On compute node, modify /etc/nova/nova.conf to have "cpu_allocation_ratio = -1.0"
* Restart nova-compute (n-cpu) and nova-compute service is up and running (we should expect nova-compute to fail to start)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/344254

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/344254
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=fcf2a644fbe6efc2bfd2810add36a099cadd959e
Submitter: Jenkins
Branch: master

commit fcf2a644fbe6efc2bfd2810add36a099cadd959e
Author: Vu Tran <email address hidden>
Date: Mon Aug 29 14:05:25 2016 -0400

    Not allow overcommit ratios to be negative

    Currently the three overcommit ratios: ram_allocation_ratio,
    cpu_allocation_ratio, and disk_allocation_ratio can be set to negative values.
    It's up to the scheduler filters to impose the checks on these ratios.

    It makes more sense to make sure these 3 ratios are not negative when
    nova-compute is started. If any of these ratios is negative then nova-compute
    service will fail to start.

    Closes-Bug: #1604116
    Change-Id: Ic960e319b59910c0178e81259b2e35435f2db592

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/newton
Review: https://review.openstack.org/389017

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 15.0.0.0b1 development milestone.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lee Yarwood (<email address hidden>) on branch: stable/newton
Review: https://review.openstack.org/389017
Reason: Abandoning this review given it is not suitable for stable/newton and has not been touched for a few weeks.