Replace README to fit ePPing PAM build

Replace the generic bpf-examples README file with a README more
suitable for the purpose of this repository (archiving the ePPing PAM
2023 build).

Signed-off-by: Simon Sundberg <[email protected]>

README.md

@@ -1,14 +1,41 @@
-# Practical BPF examples
+# ePPing PAM 2023 build
 
-This git repository contains a diverse set of **practical BPF examples** that
-solve (or demonstrate) a specific use-case using BPF.
+This repository contains the code for the ePPing application that was
+used for the PAM 2023 paper "Efficient continuous latency monitoring
+with eBPF". For the most current build of ePPing please see
+[xdp-project/bpf-examples](https://github.com/simosund/bpf-examples/tree/master/pping)
+instead. The code for ePPing is usually bundled with many other cool XDP
+applications, but for this repository I have removed them to keep it
+focused on ePPing.
 
-It is meant to ease doing **rapid prototyping and development**, writing C-code
-BPF programs using libbpf.  The goal is to make it **easier for developers** to
-get started coding.
+Two different builds of ePPing were used for the experiments in the
+paper. The build in the [main
+branch](https://github.com/simosund/ePPing-PAM23/tree/main) was used
+for the performance tests, whereas the build in the [additional-output
+branch](https://github.com/simosund/ePPing-PAM23/tree/additional-output)
+(adds TSecr and ACK number to each RTT report) was used for evaluating
+the RTT accuracy and showcasing the difference between matching TCP
+timestamps vs sequence and ACK numbers.
 
-Many developers struggle to get a working BPF build environment.  The repo
-enviroment makes it easy to build/compile BPF programs by doing the necessary
-libbpf setup transparently and detect missing compile dependencies (via the
-[configure](configure) script). It is a declared goal to **make BPF programming
-more consumable** by detecting and reporting issues (when possible).
+## Build
+To build ePPing, run the following commands
+```
+git submodule update --init
+CLANG=clang-14 LLC=llc-14 ./configure
+cd pping
+make
+```
+
+Note that for the experiments ePPing was built with LLVM-14 (clang-14
+and llc-14). This build will fail to run if compiled with LLVM-15+, as
+the fix for working with LLVM-15+ was added later.
+
+## Run
+To run ePPing, run the following commands
+```
+cd pping
+sudo ./pping -i <interface> [optional args]
+```
+
+To list the optional arguments, simply run `sudo ./pping -h`. A short
+explanation of each argument can be found in pping/pping.c