# Performance

## About

Performance has two dimensions (two metrics):

Performance is a feature.

It can sometimes difficult to talk about performance when one technique improves throughput but decreases response time.

Which has the best performance ?

Vehicle Time to Paris Speed Passengers Throughput (pk/h)
Ferrari 2 hours 250 km/h 2 500
Greyhound 5 hours 100 km/h 60 6000

This two metrics are a subset of Service Level Indicator metrics.

## “Time to do the task” versus “Task par unit of time”

Vehicle Vehicle Ferrari Greyhound
Speed 160 mph 65 mph
Time to Bay Area 3.1 hours 7.7 hours
Passengers 2 60
Throughput (pm/h) 320 3900
• Time is measured in time units/job.
• Throughput is measured in jobs/time unit.

Then $$\text{time} = \frac{1}{\text{throughput}}$$

The formula is only valid for one job at a time, It takes 4 months to grow a tomato. Can you only grow 3 tomatoes a year ??

## Rule

Minimize

The bucket list of performance gains:

• don’t do it
• do it only once
• do it less often
• do it more efficiently

Performance is a funny thing. You can't make computers faster, you can only make them:

• do less wasted work
• or spend less time waiting.

## Example

A data system may drop some data of a query in order to be able to calculate results in a reasonable time using a reasonable amount of computing resources

## Quote

Within performance issues, encoding/decoding is often the most significant cost.

## Documentation / Reference

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