On 06/30/2015 02:42 AM, ChangBo Guo wrote:
CPU frequency  is an import performance parameter,  currently  nova
drivers just  report cpu_info without frequency.   we stored the compute
node cpu_info in database with colum compute_nodes.cpu_info,  we can add
the frequency  easily.

The usage of  cpu frequency  I  can think is used to schedule to meet
applications which need high frequency.  add a frequency based filter ?
if we need this , I would like to propose  a spec for this .


There are two steps to leverage cpu frequency:
1.  report cpu frequency  and record the value,  nova hypervisor-show
will include the value .

2.  filter compute nodes based  cpu frequency.
     add a new scheduler filter to do that

before I start to do these stuff.  I would like to your  input .

Do we need leverage CPU frequency  in Nova ?
if yes, do we need a new filter  or  leverage existing filter to use
frequency ?

Like Dan B, I question whether CPU frequency really is a useful metric for scheduling decisions.

That said, it is already possible to use CPU frequency in the MetricsWeigher scheduler weigher. The compute monitor plugin system is currently being overhauled [1], but the functionality to monitor CPU-related metrics already exists in Nova and can be enabled by doing the following in your nova-compute nova.conf:

compute_monitors = ComputeDriverCPUMonitor

Note that with the refactoring of the monitoring plugin interface, the above option will change due to using stevedore to load monitor extensions:

compute_monitors = nova.compute.monitors.cpu.virt_driver:Monitor

In your Nova scheduler nova.conf, you will need to add the following in the [metrics] section of the file:

weights_setting = cpu.frequency=10.0

Again, I'm not saying that the above will result in any appreciable enhancement to the scheduler's decision-making, but it will do what you're trying to accomplish :)

Best,
-jay

[1] https://review.openstack.org/#/q/status:open+project:openstack/nova+branch:master+topic:bug/1468012,n,z

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