diff -r e337d8247375 -r 0b32206c3c86 contrib/perf.py
--- a/contrib/perf.py	Tue Oct 08 02:16:15 2019 -0400
+++ b/contrib/perf.py	Tue Oct 08 01:49:18 2019 -0400
@@ -1163,6 +1163,10 @@
 
 @command(b'perfdirfoldmap', formatteropts)
 def perfdirfoldmap(ui, repo, **opts):
+    """benchmap a `dirstate._map.dirfoldmap.get()` request
+
+    The dirstate dirfoldmap cache is dropped between every request.
+    """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     dirstate = repo.dirstate