diff --git a/contrib/perf.py b/contrib/perf.py
--- a/contrib/perf.py
+++ b/contrib/perf.py
@@ -1142,6 +1142,10 @@ def perfdirstatedirs(ui, repo, **opts):
 
 @command(b'perfdirstatefoldmap', formatteropts)
 def perfdirstatefoldmap(ui, repo, **opts):
+    """benchmap a `dirstate._map.filefoldmap.get()` request
+
+    The dirstate filefoldmap cache is dropped between every request.
+    """
     opts = _byteskwargs(opts)
     timer, fm = gettimer(ui, opts)
     dirstate = repo.dirstate
diff --git a/tests/test-contrib-perf.t b/tests/test-contrib-perf.t
--- a/tests/test-contrib-perf.t
+++ b/tests/test-contrib-perf.t
@@ -111,7 +111,7 @@ perfstatus
    perfdirstatedirs
                  benchmap a 'dirstate.hasdir' call from an empty 'dirs' cache
    perfdirstatefoldmap
-                 (no help text available)
+                 benchmap a 'dirstate._map.filefoldmap.get()' request
    perfdirstatewrite
                  (no help text available)
    perfdiscovery