Real Life
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brendangregg.com
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brendangregg.com
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just heard
“w
e
have
a
great average” →
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The problem with averages:
If you put one hand in a bucket of ice
and the other in a bucket of hot coals,
on average, you’re comfortable.
Erik Michaels-Ober
@sferik
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Averages
mask problems
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Graph
the median
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Graph
95th percentile
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Graph
99th percentile
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Aggregate graphs
another average
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No content
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Breakout graphs
show each source
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No content
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Seriously, do it
Visualize your data
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graphic by Schutz and Avenue, CC-Attribution-ShareAlike, taken from from the Wikipedia article on Anscombe's quartet
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Average of X: 9 Average of X: 9
Average of X: 9 Average of X: 9
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Average of Y: 7.50 Average of Y: 7.50
Average of Y: 7.50 Average of Y: 7.50
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Average of X
Average of Y
Variance of X
Variance of Y
Correlation of X and Y
Linear regression
All four data sets have the same
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Aggregate alerts
more dead servers
than alive servers
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site’s up if any
servers are up!
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Breakout alerts
first dead server
not all the servers
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Servers
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Servers
you have no idea
what is going on
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really.
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Runtime lag
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Runtime lag
how do you tell you
lost consciousness?
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Runtime lag
you have it.
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Runtime lag
you have it.
how bad is it?
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VM lag
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VM lag
do you have it?
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VM lag
do you check for it?
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VM lag
do you know how
to check for it?
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Routing
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Routing
your app has this
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Routing
how does it work?
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Development
App
You
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Production
People Router
Server
App
App
Router
Server
App
App
Router