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Baselines are more important than the benchmark
Witness Mark
"It is too slow": These four words launch nearly every performance analysis. Slow is an ambiguous term, which may equally represent very different concerns, including change in performance compared with a previous versions or how the same software ran on some previous day. Equally, it may represent inadequate performance compared with what performance a system is believed to be capable of delivering.
I have examined this second definition before [1], studying how the library of CPU benchmarks published by the 7-Zip project [2] could be used to compare with observed CPU performance on my system. This month, I explore how to define baselines for I/O, including the storage and network subsystems. The I/O paths are more vulnerable to performance setbacks because of system or software misconfiguration than CPU or memory, having to rely on multiple components to perform optimally – or in the case of the network, external hops through the Internet itself.
The Network Is the Computer
Setting a baseline is essentially figuring out what is the highest performance that can be expected if the system on hand is properly configured. The simplest tool reproducing the tested configuration is always to be preferred, to limit the multitude of variables under consideration. Usually, the application the system is meant for is a much richer and more complex beast, and if you are testing for performance, usually the application has already shown undesirable behavior anyway.
The iperf3 tool [3] is your go-to utility to test a network path's baseline, end to end. Found in the Ubuntu Universe repository (install with apt install iperf3) and in macOS's Brew (brew install iperf3), it
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