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An exponential moving average (
ema), also known as an exponentially weighted moving average (
is a first-order infinite impulse response filter that applies weighting factors which decrease
exponentially. The weighting for each older datum decreases exponentially, never reaching zero.
In simple terms, this is like an average value, but more recent values are given more weight.
Netdata automatically adjusts the weight (
alpha) based on the number of values processed,
using the formula:
window = max(number of values, 15)
alpha = 2 / (window + 1)
You can change the fixed value
15 by setting in
ses max window = 15
how to use
Use it in alarms like this:
lookup: ses -1m unaligned of my_dimension
warn: $this > 1000
ses does not change the units. For example, if the chart units is
requests/sec, the exponential
moving average will be again expressed in the same units.
It can also be used in APIs and badges as
&group=ses in the URL.
Examining last 1 minute
successful web server responses: