diff --git a/tensorboard/backend/event_processing/BUILD b/tensorboard/backend/event_processing/BUILD
index 18973ffc05..6b37a914b0 100644
--- a/tensorboard/backend/event_processing/BUILD
+++ b/tensorboard/backend/event_processing/BUILD
@@ -13,6 +13,7 @@ py_library(
     srcs_version = "PY2AND3",
     deps = [
         "//tensorboard:expect_tensorflow_installed",
+        "@org_pythonhosted_six",
     ],
 )
 
@@ -24,6 +25,7 @@ py_test(
     deps = [
         ":io_wrapper",
         "//tensorboard:expect_tensorflow_installed",
+        "@org_pythonhosted_six",
     ],
 )
 
@@ -94,6 +96,7 @@ py_library(
     deps = [
         ":directory_watcher",
         ":event_file_loader",
+        ":io_wrapper",
         ":plugin_asset_util",
         ":reservoir",
         "//tensorboard:data_compat",
@@ -188,7 +191,7 @@ py_library(
     srcs_version = "PY2AND3",
     deps = [
         ":event_accumulator",
-        ":event_multiplexer",
+        ":io_wrapper",
         "//tensorboard:expect_tensorflow_installed",
     ],
 )
diff --git a/tensorboard/backend/event_processing/directory_watcher_test.py b/tensorboard/backend/event_processing/directory_watcher_test.py
index b0727b6624..c65a2e238a 100644
--- a/tensorboard/backend/event_processing/directory_watcher_test.py
+++ b/tensorboard/backend/event_processing/directory_watcher_test.py
@@ -193,7 +193,12 @@ def Fake(*args, **kwargs):
 
     FakeFactory.has_been_called = False
 
-    for stub_name in ['ListDirectoryAbsolute', 'ListRecursively']:
+    stub_names = [
+        'ListDirectoryAbsolute',
+        'ListRecursivelyViaGlobbing',
+        'ListRecursivelyViaWalking',
+    ]
+    for stub_name in stub_names:
       self.stubs.Set(io_wrapper, stub_name,
                      FakeFactory(getattr(io_wrapper, stub_name)))
     for stub_name in ['IsDirectory', 'Exists', 'Stat']:
diff --git a/tensorboard/backend/event_processing/event_accumulator.py b/tensorboard/backend/event_processing/event_accumulator.py
index 81a79fbc32..742863b0dc 100644
--- a/tensorboard/backend/event_processing/event_accumulator.py
+++ b/tensorboard/backend/event_processing/event_accumulator.py
@@ -18,13 +18,13 @@
 from __future__ import print_function
 
 import collections
-import os
 import threading
 
 import tensorflow as tf
 
 from tensorboard.backend.event_processing import directory_watcher
 from tensorboard.backend.event_processing import event_file_loader
+from tensorboard.backend.event_processing import io_wrapper
 from tensorboard.backend.event_processing import plugin_asset_util
 from tensorboard.backend.event_processing import reservoir
 from tensorboard.plugins.distribution import compressor
@@ -98,23 +98,6 @@
 }
 
 
-def IsTensorFlowEventsFile(path):
-  """Check the path name to see if it is probably a TF Events file.
-
-  Args:
-    path: A file path to check if it is an event file.
-
-  Raises:
-    ValueError: If the path is an empty string.
-
-  Returns:
-    If path is formatted like a TensorFlowEventsFile.
-  """
-  if not path:
-    raise ValueError('Path must be a nonempty string')
-  return 'tfevents' in tf.compat.as_str_any(os.path.basename(path))
-
-
 class EventAccumulator(object):
   """An `EventAccumulator` takes an event generator, and accumulates the values.
 
@@ -747,11 +730,13 @@ def _GeneratorFromPath(path):
   """Create an event generator for file or directory at given path string."""
   if not path:
     raise ValueError('path must be a valid string')
-  if IsTensorFlowEventsFile(path):
+  if io_wrapper.IsTensorFlowEventsFile(path):
     return event_file_loader.EventFileLoader(path)
   else:
     return directory_watcher.DirectoryWatcher(
-        path, event_file_loader.EventFileLoader, IsTensorFlowEventsFile)
+        path,
+        event_file_loader.EventFileLoader,
+        io_wrapper.IsTensorFlowEventsFile)
 
 
 def _ParseFileVersion(file_version):
diff --git a/tensorboard/backend/event_processing/event_file_inspector.py b/tensorboard/backend/event_processing/event_file_inspector.py
index dab4196376..c7852bba34 100644
--- a/tensorboard/backend/event_processing/event_file_inspector.py
+++ b/tensorboard/backend/event_processing/event_file_inspector.py
@@ -120,7 +120,7 @@
 
 from tensorboard.backend.event_processing import event_accumulator
 from tensorboard.backend.event_processing import event_file_loader
-from tensorboard.backend.event_processing import event_multiplexer
+from tensorboard.backend.event_processing import io_wrapper
 
 FLAGS = tf.flags.FLAGS
 
@@ -323,12 +323,12 @@ def generators_from_logdir(logdir):
   Returns:
     List of event generators for each subdirectory with event files.
   """
-  subdirs = event_multiplexer.GetLogdirSubdirectories(logdir)
+  subdirs = io_wrapper.GetLogdirSubdirectories(logdir)
   generators = [
       itertools.chain(*[
           generator_from_event_file(os.path.join(subdir, f))
           for f in tf.gfile.ListDirectory(subdir)
-          if event_accumulator.IsTensorFlowEventsFile(os.path.join(subdir, f))
+          if io_wrapper.IsTensorFlowEventsFile(os.path.join(subdir, f))
       ]) for subdir in subdirs
   ]
   return generators
@@ -356,13 +356,13 @@ def get_inspection_units(logdir='', event_file='', tag=''):
     A list of InspectionUnit objects.
   """
   if logdir:
-    subdirs = event_multiplexer.GetLogdirSubdirectories(logdir)
+    subdirs = io_wrapper.GetLogdirSubdirectories(logdir)
     inspection_units = []
     for subdir in subdirs:
       generator = itertools.chain(*[
           generator_from_event_file(os.path.join(subdir, f))
           for f in tf.gfile.ListDirectory(subdir)
-          if event_accumulator.IsTensorFlowEventsFile(os.path.join(subdir, f))
+          if io_wrapper.IsTensorFlowEventsFile(os.path.join(subdir, f))
       ])
       inspection_units.append(InspectionUnit(
           name=subdir,
@@ -371,7 +371,7 @@ def get_inspection_units(logdir='', event_file='', tag=''):
     if inspection_units:
       print('Found event files in:\n{}\n'.format('\n'.join(
           [u.name for u in inspection_units])))
-    elif event_accumulator.IsTensorFlowEventsFile(logdir):
+    elif io_wrapper.IsTensorFlowEventsFile(logdir):
       print(
           'It seems that {} may be an event file instead of a logdir. If this '
           'is the case, use --event_file instead of --logdir to pass '
diff --git a/tensorboard/backend/event_processing/event_multiplexer.py b/tensorboard/backend/event_processing/event_multiplexer.py
index 37884188c3..cdc498d4f9 100644
--- a/tensorboard/backend/event_processing/event_multiplexer.py
+++ b/tensorboard/backend/event_processing/event_multiplexer.py
@@ -166,7 +166,7 @@ def AddRunsFromDirectory(self, path, name=None):
       The `EventMultiplexer`.
     """
     tf.logging.info('Starting AddRunsFromDirectory: %s', path)
-    for subdir in GetLogdirSubdirectories(path):
+    for subdir in io_wrapper.GetLogdirSubdirectories(path):
       tf.logging.info('Adding events from directory %s', subdir)
       rpath = os.path.relpath(subdir, path)
       subname = os.path.join(name, rpath) if name else rpath
@@ -480,17 +480,3 @@ def GetAccumulator(self, run):
     """
     with self._accumulators_mutex:
       return self._accumulators[run]
-
-
-def GetLogdirSubdirectories(path):
-  """Returns subdirectories with event files on path."""
-  if tf.gfile.Exists(path) and not tf.gfile.IsDirectory(path):
-    raise ValueError('GetLogdirSubdirectories: path exists and is not a '
-                     'directory, %s' % path)
-
-  # ListRecursively just yields nothing if the path doesn't exist.
-  return (
-      subdir
-      for (subdir, files) in io_wrapper.ListRecursively(path)
-      if list(filter(event_accumulator.IsTensorFlowEventsFile, files))
-  )
diff --git a/tensorboard/backend/event_processing/io_wrapper.py b/tensorboard/backend/event_processing/io_wrapper.py
index c185f26a4f..a2635e3388 100644
--- a/tensorboard/backend/event_processing/io_wrapper.py
+++ b/tensorboard/backend/event_processing/io_wrapper.py
@@ -17,36 +17,182 @@
 from __future__ import division
 from __future__ import print_function
 
+import collections
 import os
+import re
 
+import six
 import tensorflow as tf
 
+_ESCAPE_GLOB_CHARACTERS_REGEX = re.compile('([*?[])')
 
+
+# TODO(chihuahua): Rename this method to use camel-case for GCS (Gcs).
 def IsGCSPath(path):
   return path.startswith("gs://")
 
 
+def IsCnsPath(path):
+  return path.startswith("/cns/")
+
+
+def IsTensorFlowEventsFile(path):
+  """Check the path name to see if it is probably a TF Events file.
+
+  Args:
+    path: A file path to check if it is an event file.
+
+  Raises:
+    ValueError: If the path is an empty string.
+
+  Returns:
+    If path is formatted like a TensorFlowEventsFile.
+  """
+  if not path:
+    raise ValueError('Path must be a nonempty string')
+  return 'tfevents' in tf.compat.as_str_any(os.path.basename(path))
+
+
 def ListDirectoryAbsolute(directory):
   """Yields all files in the given directory. The paths are absolute."""
   return (os.path.join(directory, path)
           for path in tf.gfile.ListDirectory(directory))
 
 
-def ListRecursively(top):
+def _EscapeGlobCharacters(path):
+  """Escapes the glob characters in a path.
+
+  Python 3 has a glob.escape method, but python 2 lacks it, so we manually
+  implement this method.
+
+  Args:
+    path: The absolute path to escape.
+
+  Returns:
+    The escaped path string.
+  """
+  drive, path = os.path.splitdrive(path)
+  return '%s%s' % (drive, _ESCAPE_GLOB_CHARACTERS_REGEX.sub(r'[\1]', path))
+
+
+def ListRecursivelyViaGlobbing(top):
+  """Recursively lists all files within the directory.
+
+  This method does not list subdirectories (in addition to regular files), and
+  the file paths are all absolute. If the directory does not exist, this yields
+  nothing.
+
+  This method does so by glob-ing deeper and deeper directories, ie
+  foo/*, foo/*/*, foo/*/*/* and so on until all files are listed. All file
+  paths are absolute, and this method lists subdirectories too.
+
+  For certain file systems, Globbing via this method may prove
+  significantly faster than recursively walking a directory.
+  Specifically, file systems that implement analogs to TensorFlow's
+  FileSystem.GetMatchingPaths method could save costly disk reads by using
+  this method. However, for other file systems, this method might prove slower
+  because the file system performs a walk per call to glob (in which case it
+  might as well just perform 1 walk).
+
+  Args:
+    top: A path to a directory.
+
+  Yields:
+    A (dir_path, file_paths) tuple for each directory/subdirectory.
+  """
+  current_glob_string = os.path.join(_EscapeGlobCharacters(top), '*')
+  level = 0
+
+  while True:
+    tf.logging.info('GlobAndListFiles: Starting to glob level %d', level)
+    glob = tf.gfile.Glob(current_glob_string)
+    tf.logging.info(
+        'GlobAndListFiles: %d files glob-ed at level %d', len(glob), level)
+
+    if not glob:
+      # This subdirectory level lacks files. Terminate.
+      return
+
+    # Map subdirectory to a list of files.
+    pairs = collections.defaultdict(list)
+    for file_path in glob:
+      pairs[os.path.dirname(file_path)].append(file_path)
+    for dir_name, file_paths in six.iteritems(pairs):
+      yield (dir_name, tuple(file_paths))
+
+    if len(pairs) == 1:
+      # If at any point the glob returns files that are all in a single
+      # directory, replace the current globbing path with that directory as the
+      # literal prefix. This should improve efficiency in cases where a single
+      # subdir is significantly deeper than the rest of the sudirs.
+      current_glob_string = os.path.join(list(pairs.keys())[0], '*')
+
+    # Iterate to the next level of subdirectories.
+    current_glob_string = os.path.join(current_glob_string, '*')
+    level += 1
+
+
+def ListRecursivelyViaWalking(top):
   """Walks a directory tree, yielding (dir_path, file_paths) tuples.
 
   For each of `top` and its subdirectories, yields a tuple containing the path
   to the directory and the path to each of the contained files.  Note that
-  unlike os.Walk()/tf.gfile.Walk(), this does not list subdirectories and the
-  file paths are all absolute.
+  unlike os.Walk()/tf.gfile.Walk()/ListRecursivelyViaGlobbing, this does not
+  list subdirectories. The file paths are all absolute. If the directory does
+  not exist, this yields nothing.
 
-  If the directory does not exist, this yields nothing.
+  Walking may be incredibly slow on certain file systems.
 
   Args:
-    top: A path to a directory..
+    top: A path to a directory.
+
   Yields:
-    A list of (dir_path, file_paths) tuples.
+    A (dir_path, file_paths) tuple for each directory/subdirectory.
   """
   for dir_path, _, filenames in tf.gfile.Walk(top):
     yield (dir_path, (os.path.join(dir_path, filename)
                       for filename in filenames))
+
+
+def GetLogdirSubdirectories(path):
+  """Obtains all subdirectories with events files.
+
+  The order of the subdirectories returned is unspecified. The internal logic
+  that determines order varies by scenario.
+
+  Args:
+    path: The path to a directory under which to find subdirectories.
+
+  Returns:
+    A tuple of absolute paths of all subdirectories each with at least 1 events
+    file directly within the subdirectory.
+
+  Raises:
+    ValueError: If the path passed to the method exists and is not a directory.
+  """
+  if not tf.gfile.Exists(path):
+    # No directory to traverse.
+    return ()
+
+  if not tf.gfile.IsDirectory(path):
+    raise ValueError('GetLogdirSubdirectories: path exists and is not a '
+                     'directory, %s' % path)
+
+  if IsGCSPath(path) or IsCnsPath(path):
+    # Glob-ing for files can be significantly faster than recursively
+    # walking through directories for some file systems.
+    tf.logging.info(
+        'GetLogdirSubdirectories: Starting to list directories via glob-ing.')
+    traversal_method = ListRecursivelyViaGlobbing
+  else:
+    # For other file systems, the glob-ing based method might be slower because
+    # each call to glob could involve performing a recursive walk.
+    tf.logging.info(
+        'GetLogdirSubdirectories: Starting to list directories via walking.')
+    traversal_method = ListRecursivelyViaWalking
+
+  return (
+      subdir
+      for (subdir, files) in traversal_method(path)
+      if any(IsTensorFlowEventsFile(f) for f in files)
+  )
diff --git a/tensorboard/backend/event_processing/io_wrapper_test.py b/tensorboard/backend/event_processing/io_wrapper_test.py
index a6df9e346c..0621df09e8 100644
--- a/tensorboard/backend/event_processing/io_wrapper_test.py
+++ b/tensorboard/backend/event_processing/io_wrapper_test.py
@@ -20,6 +20,7 @@
 import os
 import tempfile
 
+import six
 import tensorflow as tf
 
 from tensorboard.backend.event_processing import io_wrapper
@@ -32,113 +33,277 @@ def testIsGcsPathIsTrue(self):
   def testIsGcsPathIsFalse(self):
     self.assertFalse(io_wrapper.IsGCSPath('/tmp/foo'))
 
+  def testIsCnsPathTrue(self):
+    self.assertTrue(io_wrapper.IsCnsPath('/cns/foo/bar'))
+
+  def testIsCnsPathFalse(self):
+    self.assertFalse(io_wrapper.IsCnsPath('/tmp/foo'))
+
+  def testIsIsTensorFlowEventsFileTrue(self):
+    self.assertTrue(
+        io_wrapper.IsTensorFlowEventsFile(
+            '/logdir/events.out.tfevents.1473720042.com'))
+
+  def testIsIsTensorFlowEventsFileFalse(self):
+    self.assertFalse(
+        io_wrapper.IsTensorFlowEventsFile('/logdir/model.ckpt'))
+
+  def testIsIsTensorFlowEventsFileWithEmptyInput(self):
+    with six.assertRaisesRegex(self,
+                               ValueError,
+                               r'Path must be a nonempty string'):
+      io_wrapper.IsTensorFlowEventsFile('')
+
   def testListDirectoryAbsolute(self):
     temp_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
+    self._CreateDeepDirectoryStructure(temp_dir)
 
-    # Add a few subdirectories.
-    directory_names = (
+    expected_files = (
         'foo',
         'bar',
-        'we/must/go/deeper'
+        'quuz',
+        'a.tfevents.1',
+        'model.ckpt',
+        'waldo',
+    )
+    self.assertItemsEqual(
+        (os.path.join(temp_dir, f) for f in expected_files),
+        io_wrapper.ListDirectoryAbsolute(temp_dir))
+
+  def testListRecursivelyViaGlobbing(self):
+    temp_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
+    self._CreateDeepDirectoryStructure(temp_dir)
+    expected = [
+        ['', [
+            'foo',
+            'bar',
+            'a.tfevents.1',
+            'model.ckpt',
+            'quuz',
+            'waldo',
+        ]],
+        ['bar', [
+            'b.tfevents.1',
+            'red_herring.txt',
+            'baz',
+            'quux',
+        ]],
+        ['bar/baz', [
+            'c.tfevents.1',
+            'd.tfevents.1',
+        ]],
+        ['bar/quux', [
+            'some_flume_output.txt',
+            'some_more_flume_output.txt',
+        ]],
+        ['quuz', [
+            'e.tfevents.1',
+            'garply',
+        ]],
+        ['quuz/garply', [
+            'f.tfevents.1',
+            'corge',
+            'grault',
+        ]],
+        ['quuz/garply/corge', [
+            'g.tfevents.1'
+        ]],
+        ['quuz/garply/grault', [
+            'h.tfevents.1',
+        ]],
+        ['waldo', [
+            'fred',
+        ]],
+        ['waldo/fred', [
+            'i.tfevents.1',
+        ]],
+    ]
+    for pair in expected:
+      # If this is not the top-level directory, prepend the high-level
+      # directory.
+      pair[0] = os.path.join(temp_dir, pair[0]) if pair[0] else temp_dir
+      pair[1] = [os.path.join(pair[0], f) for f in pair[1]]
+    self._CompareFilesPerSubdirectory(
+        expected, io_wrapper.ListRecursivelyViaGlobbing(temp_dir))
+
+  def testListRecursivelyViaGlobbingForPathWithGlobCharacters(self):
+    temp_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
+    directory_names = (
+        'ba*',
+        'ba*/subdirectory',
+        'bar',
     )
     for directory_name in directory_names:
       os.makedirs(os.path.join(temp_dir, directory_name))
 
-    # Add a few files to the directory.
     file_names = (
-        'events.out.tfevents.1473720381.foo.com',
-        'model.ckpt',
-        'we/must_not_include_this_file_in_the_listing.txt'
+        'ba*/a.tfevents.1',
+        'ba*/subdirectory/b.tfevents.1',
+        'bar/c.tfevents.1',
     )
     for file_name in file_names:
       open(os.path.join(temp_dir, file_name), 'w').close()
 
-    expected_files = (
-        'foo',
+    expected = [
+        ['', [
+            'a.tfevents.1',
+            'subdirectory',
+        ]],
+        ['subdirectory', [
+            'b.tfevents.1',
+        ]],
+        # The contents of the bar subdirectory should be excluded from
+        # this listing because the * character should have been escaped.
+    ]
+    top = os.path.join(temp_dir, 'ba*')
+    for pair in expected:
+      # If this is not the top-level directory, prepend the high-level
+      # directory.
+      pair[0] = os.path.join(top, pair[0]) if pair[0] else top
+      pair[1] = [os.path.join(pair[0], f) for f in pair[1]]
+    self._CompareFilesPerSubdirectory(
+        expected, io_wrapper.ListRecursivelyViaGlobbing(top))
+
+  def testListRecursivelyViaWalking(self):
+    temp_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
+    self._CreateDeepDirectoryStructure(temp_dir)
+    expected = [
+        ['', [
+            'a.tfevents.1',
+            'model.ckpt',
+        ]],
+        ['foo', []],
+        ['bar', [
+            'b.tfevents.1',
+            'red_herring.txt',
+        ]],
+        ['bar/baz', [
+            'c.tfevents.1',
+            'd.tfevents.1',
+        ]],
+        ['bar/quux', [
+            'some_flume_output.txt',
+            'some_more_flume_output.txt',
+        ]],
+        ['quuz', [
+            'e.tfevents.1',
+        ]],
+        ['quuz/garply', [
+            'f.tfevents.1',
+        ]],
+        ['quuz/garply/corge', [
+            'g.tfevents.1',
+        ]],
+        ['quuz/garply/grault', [
+            'h.tfevents.1',
+        ]],
+        ['waldo', []],
+        ['waldo/fred', [
+            'i.tfevents.1',
+        ]],
+    ]
+    for pair in expected:
+      # If this is not the top-level directory, prepend the high-level
+      # directory.
+      pair[0] = os.path.join(temp_dir, pair[0]) if pair[0] else temp_dir
+      pair[1] = [os.path.join(pair[0], f) for f in pair[1]]
+    self._CompareFilesPerSubdirectory(
+        expected, io_wrapper.ListRecursivelyViaWalking(temp_dir))
+
+  def testGetLogdirSubdirectories(self):
+    temp_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
+    self._CreateDeepDirectoryStructure(temp_dir)
+    # Only subdirectories that immediately contains at least 1 events
+    # file should be listed.
+    expected = [
+        '',
         'bar',
-        'we',
-        'events.out.tfevents.1473720381.foo.com',
-        'model.ckpt',
-    )
+        'bar/baz',
+        'quuz',
+        'quuz/garply',
+        'quuz/garply/corge',
+        'quuz/garply/grault',
+        'waldo/fred',
+    ]
     self.assertItemsEqual(
-        (os.path.join(temp_dir, f) for f in expected_files),
-        io_wrapper.ListDirectoryAbsolute(temp_dir))
+        [(os.path.join(temp_dir, subdir) if subdir else temp_dir)
+         for subdir in expected],
+        io_wrapper.GetLogdirSubdirectories(temp_dir))
 
-  def testListRecursivelyForNestedFiles(self):
-    temp_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
+  def _CreateDeepDirectoryStructure(self, top_directory):
+    """Creates a reasonable deep structure of subdirectories with files.
 
+    Args:
+      top_directory: The absolute path of the top level directory in
+        which to create the directory structure.
+    """
     # Add a few subdirectories.
     directory_names = (
+        # An empty directory.
         'foo',
+        # A directory with an events file (and a text file).
         'bar',
+        # A deeper directory with events files.
         'bar/baz',
+        # A non-empty subdirectory that lacks event files (should be ignored).
+        'bar/quux',
+        # This 3-level deep set of subdirectories tests logic that replaces the
+        # full glob string with an absolute path prefix if there is only 1
+        # subdirectory in the final mapping.
+        'quuz/garply',
+        'quuz/garply/corge',
+        'quuz/garply/grault',
+        # A directory that lacks events files, but contains a subdirectory
+        # with events files (first level should be ignored, second level should
+        # be included).
+        'waldo',
+        'waldo/fred',
     )
     for directory_name in directory_names:
-      os.makedirs(os.path.join(temp_dir, directory_name))
+      os.makedirs(os.path.join(top_directory, directory_name))
 
     # Add a few files to the directory.
     file_names = (
-        'events.out.tfevents.1473720381.meep.com',
+        'a.tfevents.1',
         'model.ckpt',
-        'bar/events.out.tfevents.1473720382.bar.com',
+        'bar/b.tfevents.1',
         'bar/red_herring.txt',
-        'bar/baz/events.out.tfevents.1473720383.baz.com',
-        'bar/baz/events.out.tfevents.1473720384.baz.com',
+        'bar/baz/c.tfevents.1',
+        'bar/baz/d.tfevents.1',
+        'bar/quux/some_flume_output.txt',
+        'bar/quux/some_more_flume_output.txt',
+        'quuz/e.tfevents.1',
+        'quuz/garply/f.tfevents.1',
+        'quuz/garply/corge/g.tfevents.1',
+        'quuz/garply/grault/h.tfevents.1',
+        'waldo/fred/i.tfevents.1',
     )
     for file_name in file_names:
-      open(os.path.join(temp_dir, file_name), 'w').close()
-
-    # There were 4 subdirectories in total.
-    listing = io_wrapper.ListRecursively(temp_dir)
-    directory_to_listing = {
-        dir: list(generator) for (dir, generator) in listing}
-    expected = (
-        'foo',
-        'bar',
-        'bar/baz'
-    )
-    self.assertItemsEqual(
-        [os.path.join(temp_dir, f) for f in expected] + [temp_dir],
-        directory_to_listing.keys())
-
-    # Test for the listings of individual directories.
-    expected = (
-        'events.out.tfevents.1473720381.meep.com',
-        'model.ckpt',
-    )
-    self.assertItemsEqual(
-        (os.path.join(temp_dir, f) for f in expected),
-        directory_to_listing[temp_dir])
-
-    expected = ()
-    self.assertItemsEqual(
-        (os.path.join(temp_dir, 'foo', f) for f in expected),
-        directory_to_listing[os.path.join(temp_dir, 'foo')])
+      open(os.path.join(top_directory, file_name), 'w').close()
 
-    expected = (
-        'events.out.tfevents.1473720382.bar.com',
-        'red_herring.txt',
-    )
-    self.assertItemsEqual(
-        (os.path.join(temp_dir, 'bar', f) for f in expected),
-        directory_to_listing[os.path.join(temp_dir, 'bar')])
+  def _CompareFilesPerSubdirectory(self, expected, gotten):
+    """Compares iterables of (subdirectory path, list of absolute paths)
 
-    expected = (
-        'events.out.tfevents.1473720383.baz.com',
-        'events.out.tfevents.1473720384.baz.com',
-    )
+    Args:
+      expected: The expected iterable of 2-tuples.
+      gotten: The gotten iterable of 2-tuples.
+    """
+    expected_directory_to_listing = {
+        result[0]: list(result[1]) for result in expected}
+    gotten_directory_to_listing = {
+        result[0]: list(result[1]) for result in gotten}
     self.assertItemsEqual(
-        (os.path.join(temp_dir, 'bar/baz', f) for f in expected),
-        directory_to_listing[os.path.join(temp_dir, 'bar/baz')])
+        expected_directory_to_listing.keys(),
+        gotten_directory_to_listing.keys())
 
-  def testListRecursivelyForEmptyDirectory(self):
-    empty_dir = tempfile.mkdtemp(prefix=self.get_temp_dir())
-    subdirectory_entries = list(io_wrapper.ListRecursively(empty_dir))
-    self.assertEqual(1, len(subdirectory_entries))
+    for subdirectory, expected_listing in expected_directory_to_listing.items():
+      gotten_listing = gotten_directory_to_listing[subdirectory]
+      self.assertItemsEqual(
+          expected_listing,
+          gotten_listing,
+          'Files for subdirectory %r must match. Expected %r. Got %r.' % (
+              subdirectory, expected_listing, gotten_listing))
 
-    entry = subdirectory_entries[0]
-    self.assertEqual(empty_dir, entry[0])
-    self.assertItemsEqual((), entry[1])
 
 
 if __name__ == '__main__':
diff --git a/tensorboard/backend/event_processing/plugin_event_accumulator.py b/tensorboard/backend/event_processing/plugin_event_accumulator.py
index 23aba29814..9d8675a92a 100644
--- a/tensorboard/backend/event_processing/plugin_event_accumulator.py
+++ b/tensorboard/backend/event_processing/plugin_event_accumulator.py
@@ -18,7 +18,6 @@
 from __future__ import print_function
 
 import collections
-import os
 import threading
 
 import six
@@ -27,6 +26,7 @@
 from tensorboard import data_compat
 from tensorboard.backend.event_processing import directory_watcher
 from tensorboard.backend.event_processing import event_file_loader
+from tensorboard.backend.event_processing import io_wrapper
 from tensorboard.backend.event_processing import plugin_asset_util
 from tensorboard.backend.event_processing import reservoir
 
@@ -57,23 +57,6 @@
 _TENSOR_RESERVOIR_KEY = "."  # arbitrary
 
 
-def IsTensorFlowEventsFile(path):
-  """Check the path name to see if it is probably a TF Events file.
-
-  Args:
-    path: A file path to check if it is an event file.
-
-  Raises:
-    ValueError: If the path is an empty string.
-
-  Returns:
-    If path is formatted like a TensorFlowEventsFile.
-  """
-  if not path:
-    raise ValueError('Path must be a nonempty string')
-  return 'tfevents' in tf.compat.as_str_any(os.path.basename(path))
-
-
 class EventAccumulator(object):
   """An `EventAccumulator` takes an event generator, and accumulates the values.
 
@@ -577,11 +560,13 @@ def _GeneratorFromPath(path):
   """Create an event generator for file or directory at given path string."""
   if not path:
     raise ValueError('path must be a valid string')
-  if IsTensorFlowEventsFile(path):
+  if io_wrapper.IsTensorFlowEventsFile(path):
     return event_file_loader.EventFileLoader(path)
   else:
     return directory_watcher.DirectoryWatcher(
-        path, event_file_loader.EventFileLoader, IsTensorFlowEventsFile)
+        path,
+        event_file_loader.EventFileLoader,
+        io_wrapper.IsTensorFlowEventsFile)
 
 
 def _ParseFileVersion(file_version):
diff --git a/tensorboard/backend/event_processing/plugin_event_multiplexer.py b/tensorboard/backend/event_processing/plugin_event_multiplexer.py
index 621fe146f9..67a5e9e5b5 100644
--- a/tensorboard/backend/event_processing/plugin_event_multiplexer.py
+++ b/tensorboard/backend/event_processing/plugin_event_multiplexer.py
@@ -172,7 +172,7 @@ def AddRunsFromDirectory(self, path, name=None):
       The `EventMultiplexer`.
     """
     tf.logging.info('Starting AddRunsFromDirectory: %s', path)
-    for subdir in GetLogdirSubdirectories(path):
+    for subdir in io_wrapper.GetLogdirSubdirectories(path):
       tf.logging.info('Adding run from directory %s', subdir)
       rpath = os.path.relpath(subdir, path)
       subname = os.path.join(name, rpath) if name else rpath
@@ -432,17 +432,3 @@ def GetAccumulator(self, run):
     """
     with self._accumulators_mutex:
       return self._accumulators[run]
-
-
-def GetLogdirSubdirectories(path):
-  """Returns subdirectories with event files on path."""
-  if tf.gfile.Exists(path) and not tf.gfile.IsDirectory(path):
-    raise ValueError('GetLogdirSubdirectories: path exists and is not a '
-                     'directory, %s' % path)
-
-  # ListRecursively just yields nothing if the path doesn't exist.
-  return (
-      subdir
-      for (subdir, files) in io_wrapper.ListRecursively(path)
-      if list(filter(event_accumulator.IsTensorFlowEventsFile, files))
-  )