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+# NFP Benchmarks for SPLs
+
+[explore-kconfig.py](bin/explore-kconfig.py) works with any product line that supports Kconfig and is capable of describing the non-functional properties of individual products.
+To do so, the product line's build system must provide the **make**, **make clean**, **make randconfig**, **make nfpvalues** and **make nfpkeys** commands.
+**make nfpvalues** is expected to print a JSON dict describing the non-functional property values of the current build;
+**make nfpkeys** is expected to print a JSON dict with meta-data about those.
+All of these commands can be changed, see `bin/explore-kconfig.py --help`.
+
+See [explore-and-model-static](examples/explore-and-model-static) for a simple example project, and [busybox.sh](examples/busybox.sh) for a more complex one.
+
+As benchmark generation employs frequent recompilation, using a tmpfs is recommended.
+Check out the product line (i.e., the benchmark target) into a directory on the tmpfs.
+Next, create a second directory used for intermediate benchmark output, and `cd` to it.
+
+Now, you can use `.../dfatool/bin/explore-kconfig.py` to benchmark the non-functional properties of various configurations, like so:
+
+```
+.../dfatool/bin/explore-kconfig.py --log-level debug --random 500 --with-neighbourhood .../my-project
+```
+
+This will benchmark 500 random configurations and additionaly explore the neighbourhood of each configuration by toggling boolean variables and exploring the range of int/hex variables.
+Ternary features (y/m/n, as employed by the Linux kernel) are not supported.
+The benchmark results (configurations and corresponding non-functional properties) are placed in the current working directory.
+
+Once the benchmark is done, the observations can be compressed into a single file by running `.../dfatool/bin/analyze-kconfig.py --export-observations .../my-observations.json.xz --export-observations-only`.
+Depending on the value of the **DFATOOL_KCONF_WITH_CHOICE_NODES** environment variable (see below), `choice` nodes are either treated as enum variables or groups of boolean variables.
+Most approaches in the literature use boolean variables.
+Note that, when working with exported observations, **DFATOOL_KCONF_WITH_CHOICE_NODES** must have the same value in the `--export-observations` call and in subsequent `analyze-kconfig.py` calls using these observations.