How to measure system performance?

Question

System administration

Hello, tell me how to measure and compare and collect statistics about the operation of a program or service.
For example, how to compare how much a virtual machine is slower than a real one, how to make sure that on the same configured machine the same script is executed the same for 10 or 100 launches.
As for me, the evaluation criterion should be the number of processor ticks (or whatever you can advise)

Answer 1

It is impractical to measure in processor ticks, especially since modern processors can change their clock speed according to their mood.
How performance is measured depends on the task and the desired outcome.
One of the most universal approaches is to measure the real time for which a certain task was completed. If the task is running too fast, measure the time it takes to run the task multiple times.
To this are added graphs of processor load, network, disk subsystem, occupancy of RAM and virtual memory.
The issue of the presence of dips and peaks, and flat areas on the equipment load charts is considered.
A flat area under 100% indicates a lack of this resource - the system "rests" on it.
The alternation of dips and peaks indicates a suboptimal use of the resource.
An ideal computational task should provide a full load of all computing resources - this means that there is neither an excess nor a shortage of computing power in the system.