diff --git a/doc/source/admin/components.rst b/doc/source/admin/components.rst
index cc9d1810ef..e37c05c5f6 100644
--- a/doc/source/admin/components.rst
+++ b/doc/source/admin/components.rst
@@ -296,10 +296,29 @@ executor
      finger_port=79
 
 **git_dir**
-  Directory that Zuul should clone local git repositories to::
+  Directory that Zuul should clone local git repositories to.  The
+  executor keeps a local copy of every git repository it works with to
+  speed operations and perform speculative merging.
+
+  This should be on the same filesystem as **job_dir** so that when
+  git repos are cloned into the job workspaces, they can be
+  hard-linked to the local git cache.  Example::
 
      git_dir=/var/lib/zuul/git
 
+**job_dir**
+  Directory that Zuul should use to hold temporary job directories.
+  When each job is run, a new entry will be created under this
+  directory to hold the configuration and scratch workspace for that
+  job.  It will be deleted at the end of the job (unless the
+  `--keep-jobdir` command line option is specified).
+
+  This should be on the same filesystem as **git_dir** so that when
+  git repos are cloned into the job workspaces, they can be
+  hard-linked to the local git cache.  Example::
+
+     job_dir=/var/lib/zuul/jobs
+
 **log_config**
   Path to log config file for the executor process::
 
diff --git a/zuul/cmd/executor.py b/zuul/cmd/executor.py
index 6a1a2145cd..06ef0ba38b 100755
--- a/zuul/cmd/executor.py
+++ b/zuul/cmd/executor.py
@@ -82,7 +82,7 @@ class Executor(zuul.cmd.ZuulApp):
 
             self.log.info("Starting log streamer")
             streamer = zuul.lib.log_streamer.LogStreamer(
-                self.user, '0.0.0.0', self.finger_port, self.jobroot_dir)
+                self.user, '0.0.0.0', self.finger_port, self.job_dir)
 
             # Keep running until the parent dies:
             pipe_read = os.fdopen(pipe_read)
@@ -111,15 +111,15 @@ class Executor(zuul.cmd.ZuulApp):
 
         self.user = get_default(self.config, 'executor', 'user', 'zuul')
 
-        if self.config.has_option('executor', 'jobroot_dir'):
-            self.jobroot_dir = os.path.expanduser(
-                self.config.get('executor', 'jobroot_dir'))
-            if not os.path.isdir(self.jobroot_dir):
-                print("Invalid jobroot_dir: {jobroot_dir}".format(
-                    jobroot_dir=self.jobroot_dir))
+        if self.config.has_option('executor', 'job_dir'):
+            self.job_dir = os.path.expanduser(
+                self.config.get('executor', 'job_dir'))
+            if not os.path.isdir(self.job_dir):
+                print("Invalid job_dir: {job_dir}".format(
+                    job_dir=self.job_dir))
                 sys.exit(1)
         else:
-            self.jobroot_dir = tempfile.gettempdir()
+            self.job_dir = tempfile.gettempdir()
 
         self.setup_logging('executor', 'log_config')
         self.log = logging.getLogger("zuul.Executor")
@@ -134,7 +134,7 @@ class Executor(zuul.cmd.ZuulApp):
 
         ExecutorServer = zuul.executor.server.ExecutorServer
         self.executor = ExecutorServer(self.config, self.connections,
-                                       jobdir_root=self.jobroot_dir,
+                                       jobdir_root=self.job_dir,
                                        keep_jobdir=self.args.keep_jobdir,
                                        log_streaming_port=self.finger_port)
         self.executor.start()