[openstack-dev] [nova] schedule instance based on CPU frequency ?

ChangBo Guo glongwave at gmail.com
Wed Jul 1 04:23:04 UTC 2015


thanks Dan and Jay,  we don't need add new scheduler for that  :-),
what about provide cpu frequency to  api  /os-hypervisors,  that  means we
can
report this value automatically,  the value can be used in high level mange
tools.

2015-07-01 2:58 GMT+08:00 Jay Pipes <jaypipes at gmail.com>:

> 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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-- 
ChangBo Guo(gcb)
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