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Hello,
I have found the following wish-list item in the ceilometer project:
https://bugs.launchpad.net/ceilometer/+bug/1010037

I have read the associated email thread [1] and launchpad blueprint [2], 
however, the task still seems in need of further discussions. To be more 
exact, there are a few things that are still unclear:

1. How should pollster-specific polling intervals be specified? The 
blueprint mentions that publishers (I assume it means collectors) should 
specify the intervals, however I don't think that a communication 
channel between the collector and the central agent running the 
pollsters is in place.

2. Should pollsters be able to specify a polling interval (perhaps an 
inherited default) to the central agent?

3. If other ways of setting the polling intervals are probably possible 
(e.g. the config file), should there be a hierarchy specified of which 
setting override which ones?

4. Should the current periodic_interval configuration value be used as a 
safe fall back for pollsters without explicitly defined values?

5. What is the granularity of polling intervals? Seconds?


And finally an implementation idea:
I do not think that having separate periodic tasks for each pollster is 
the best solution for this problem. Assuming a second granularity for 
polling intervals, the central agent manager can maintain a map of 
pollsters and their intervals. As long as the manager is called with an 
interval that is a GCD of its pollster intervals, it can basically 
calculate how often each pollster should be queried.

Domas Monkus

[1] https://lists.launchpad.net/openstack/msg12916.html
[2] 
https://blueprints.launchpad.net/ceilometer/+spec/publisher-counters-frequency 

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