README: add more info about local testing

Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

README.rst

@@ -36,11 +36,34 @@ Having everyone test their patches locally allows for better
 scaling (no need for big central infrastructure) and hopefully
 creates an incentive for contributing.
 
+Running locally
+===============
+
+`ingest_mdir.py` can ingest patches and run the checks locally
+(by the developers on their machines). `ingest_mdir.py` should be pointed
+at a directory and run all the checks on patches that directory contains
+(patches are expected to be generated by `git format-patch`).
+
+Example:
+
+.. code-block:: bash
+
+  cd $linux
+  git format-patch HEAD~4.. -o /tmp/my-series/ --subject-prefix="PATCH net-next"
+  git checkout net-next/master -b test
+
+  cd $nipa
+  ./ingest_mdir.py --mdir /tmp/my-series/ --tree $linux
+
+Note that we need to check out the linux tree to a branch that matches the base
+on which we intend the patches to be applied. NIPA does not know what to reset
+the tree to, it will just try to apply the patches to whatever branch is
+currently checked out in the `$linux` repo.
+
 Structure
 =========
 
-The project is split into multiple programs with different
-uses.
+The project is split into multiple programs with different uses.
 
 `pw_poller.py` fetches emails from patchwork and runs tests in worker
 threads. There is one worker thread for each tree, enabling testing
@@ -52,11 +75,7 @@ and sub-dirs for each patch.
 Once tests are done another daemon - `pw_upload.py` uploads the results
 as checks to patchwork.
 
-`ingest_mdir.py` is supposed to serve the purpose of testing
-patches locally, it can be pointed at a directory and run all the
-checks on patches that directory contains (patches are expected to
-be generated by `git format-patch`). `ingest_mdir.py` has not been
-tested in a while so it's probably broken.
+`ingest_mdir.py` combines all the stages for local use.
 
 Configuration
 =============