Merge pull request #11466 from spowelljr/addBenchmarkingProcess

Add details on the benchmarking process

Author: spowelljr

site/content/en/docs/benchmarks/imageBuild/benchmarkingProcess/_index.md

@@ -0,0 +1,89 @@
+---
+title: "About the Benchmarking Process"
+linkTitle: "About the Benchmarking Process"
+weight: 1
+--- 
+
+## What's the difference between the four images?
+In the benchmarking charts you'll see four images: Few Large Layers, Few Small Layers, Many Large Layers, and Many Small Layers
+
+All the images use the same base image: `gcr.io/buildpacks/builder:v1`
+
+#### Few vs Many
+Few will copy two files while many will copy 20 files.
+
+#### Small vs Large
+Small will copy a 20MB file while large will copy a 123MB file.
+
+Using this info you can see the following:
+- Few Large Layers: copies two 123MB files
+- Few Small Layers: copies two 20MB files
+- Many Large Layers: copies 20 123MB files
+- Many Small Layers: copies 20 20MB files
+
+Finally, as the last layer, a simplistic 11 line Go app is copied in.
+
+## Iterative vs Initial
+There are two graphs for each benchmark, iterative and inital.
+
+#### Inital
+Initial simulates loading the image for the first time.
+
+All existing images and cache is removed/cleared from minikube and Docker between runs to replicate what the user would experience when loading for the first time.
+
+#### Iterative
+Iterative simulates only the Go app (last layer of the image) changing.
+
+This is the exact use case of [Skaffold](https://github.com/GoogleContainerTools/skaffold), where if the user changes a file the Go binary is rebuilt and the image is re-loaded.
+
+Bewteen runs the cache and existing image is left alone, only the Go binary is changed.
+
+
+## How are the benchmarks conducted?
+```
+// Pseudo code of running docker-env benchmark
+
+startMininkube() // minikube start --container-runtime=docker
+
+for image in [fewLargeLayers, fewSmallLayers, ...] {
+	buildGoBinary()
+
+	// inital simulation
+	for i in runCount {
+		startTimer()
+
+		runDockerEnvImageLoad(image)
+
+		stopTimer()
+
+		verifyImageSuccessfullyLoaded()
+
+		storeTimeTaken()
+
+		removeImage()
+
+		clearDockerCache()
+	}
+
+	// iterative simulation
+	for i in runCount {
+		updateGoBinary()
+
+		startTimer()
+
+		runDockerEnvImageLoad(image)
+
+		stopTimer()
+
+		verifyImageSuccessfullyLoaded()
+
+		storeTimeTaken() // skip if first run
+	}
+
+	clearDockerCache()
+
+	calculateAndRecordAverageTime()
+}
+
+deleteMinikube() // minkube delete --all
+```