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From Akila Ravihansa Perera <raviha...@wso2.com>
Subject Re: [Fixed] CEP sends very large values for gradient and second derivative of load average
Date Thu, 06 Nov 2014 19:17:29 GMT
Hi,

On Nov 6, 2014 11:37 AM, "Imesh Gunaratne" <imesh@apache.org> wrote:
>
> Thanks for your response Nirmal, please see my thoughts below:
>
> On Thu, Nov 6, 2014 at 7:38 PM, Nirmal Fernando <nirmal070125@gmail.com
> wrote:
>>
>> AFAIU if it is statistics, it's all about random data, samples and
normalization. You don't use all values to do estimations. And this is an
estimation for gradient per say!
>
>
> True, however the random data needs to be accurate as much as possible.
>>>
>>>
>> Well, statistics we are calculating is for a cluster as a whole not
member wise. Since, we autoscale a cluster.
>
>
> Yes for autoscaling a cluster the aggregated statistics should be
calculated against the cluster. However I do not think that we can mix each
statistic accorss members when calculating differences. Different members
of a cluster might be running at different resource usage levels at a given
point of time. Therefore aggregation might needed to be done at the member
level first and then on the cluster level. WDYT?

+1

We need to sample stats and aggregate them on fixed intervals before
calculating the gradients.

Thanks.

>
>
> --
> Imesh Gunaratne
>
> Technical Lead, WSO2
> Committer & PMC Member, Apache Stratos

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