Metrics filter receives wrong metric value

[Surojit Pathak]

With the following turned on in the config, /etc/nova/nova.conf
 + compute_monitors = virt_driver
 + scheduler_default_filters = MetricsFilter

nova/scheduler/filters/metrics_filter.py: MetricsFilter does not work as intended, as it gets wrong metrics values to work on, even when the data on DB is correct.

Snippet from DB -
http://paste.openstack.org/show/478481/

While printing the metrics name and value in the filter, the output shows that all the CPU metrics, computed as percentage, were received as 0.

Snippet -
cpu.user.percent 0
cpu.kernel.time 580491900000000
cpu.kernel.percent 0
cpu.idle.time 8440469190000000
cpu.idle.percent 0
cpu.iowait.time 264054730000000
cpu.percent 0
cpu.user.time 2539292510000000
cpu.frequency 2400
cpu.iowait.percent 0

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/243825

[Surojit Pathak (suro-patz)]

The detail of the nova version, on which the issue was observed -

[suro@oxy-dev nova (master)]$ pwd
/opt/stack/nova
[suro@oxy-dev nova (master)]$ git log -1
commit 4474dce9e6b847a7691fc3f01d0c594061570d73
Merge: b12e72f 768388d
Author: Jenkins <email address hidden>
Date: Mon Nov 9 06:04:10 2015 +0000

    Merge "devref: update the nova architecture doc"
[suro@oxy-dev nova (master)]$

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/243825
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ddb3c4e26f3a908de7836a8fac48360afa6aa1d7
Submitter: Jenkins
Branch: master

commit ddb3c4e26f3a908de7836a8fac48360afa6aa1d7
Author: Surojit Pathak <email address hidden>
Date: Wed Nov 25 19:21:24 2015 +0000

    Fix wrong CPU metric value in metrics_filter

    CPU metrics are reported as a normalized value in [0,1].
    When scheduler reads the data as MonitorMetric object, as part
    of update_from_compute_node(), the value of the metric gets
    lost due to a wrong type conversion, typecasting into an Integer,
    reduces it to 0.

    Note:
     - It may seem unintuitive that to fix the same, we are not changing
       the type of metric from Integer to Float. Please refer the
       discussions -
       * https://review.openstack.org/#/c/243825/
       * https://review.openstack.org/#/c/216923/
     - To summarize, we are trying to save some 'possible' downstream consumer
       of metrics updates from compute nodes, i.e. consuming from AMPQ, from
       software upgrade scenarios.

    Change-Id: Ib504af33e05dfc4d7e97b52682e27befc67d784a
    Closes-bug: #1514997

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/liberty
Review: https://review.openstack.org/300134

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/300134
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=c0dfe42382262f044471d0a852c6b724e8e81ad8
Submitter: Jenkins
Branch: stable/liberty

commit c0dfe42382262f044471d0a852c6b724e8e81ad8
Author: Surojit Pathak <email address hidden>
Date: Wed Nov 25 19:21:24 2015 +0000

    Fix wrong CPU metric value in metrics_filter

    CPU metrics are reported as a normalized value in [0,1].
    When scheduler reads the data as MonitorMetric object, as part
    of update_from_compute_node(), the value of the metric gets
    lost due to a wrong type conversion, typecasting into an Integer,
    reduces it to 0.

    Note:
     - It may seem unintuitive that to fix the same, we are not changing
       the type of metric from Integer to Float. Please refer the
       discussions -
       * https://review.openstack.org/#/c/243825/
       * https://review.openstack.org/#/c/216923/
     - To summarize, we are trying to save some 'possible' downstream consumer
       of metrics updates from compute nodes, i.e. consuming from AMPQ, from
       software upgrade scenarios.

    Change-Id: Ib504af33e05dfc4d7e97b52682e27befc67d784a
    Closes-bug: #1514997
    (cherry picked from commit ddb3c4e26f3a908de7836a8fac48360afa6aa1d7)

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/nova 12.0.4 release.