Performance
About
Performance has two dimensions (two metrics):
- either the Time to do the task from start to finish (execution time, response time, latency)
- or the tasks per unit time (throughput, bandwidth)
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.
Articles Related
“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 to do the task from start to finish most known as execution time, response time or latency
- Tasks per unit time (throughput, bandwidth)
- Time is measured in time units/job.
- Throughput is measured in jobs/time unit.
Then <MATH>\text{time} = \frac{1}{\text{throughput}}</MATH>
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
- data movements (increase spatial localization). storage: data next to the CPU (see Memory - Hierarchy). RAM better than Disk better than NAS ….
- data operation (See Performance - Algorithm (Asymptotic analysis))
- data volume (selectivity, less IO)
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
- Performance is a feature