# Performance

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.

## 3 - "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 ??

## 4 - 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.

## 5 - Quote

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