Document problems with `df' slowing down Dired.

diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index aaa53a6a0610ec8773e3c939406d6c5f1375c9bf..93180daab52b9f074029a620ba6a73c803cca500 100644 (file)
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -544,6 +544,23 @@ port or in the Cygwin library which apparently make Bash ignore the
 keyboard interrupt event sent by Emacs to Bash.  (Older Cygwin ports
 of Bash, up to b20.1, did receive SIGINT from Emacs.)
 
+* Dired is very slow.
+
+This could happen if invocation of the `df' program takes a long
+time.  Possible reasons for this include:
+
+  - ClearCase mounted filesystems (VOBs) that sometimes make `df'
+    response time extremely slow (dozens of seconds);
+
+  - slow automounters on some old versions of Unix;
+
+  - slow operation of some versions of `df'.
+
+To work around the problem, you could either (a) set the variable
+`directory-free-space-program' to nil, and thus prevent Emacs from
+invoking `df'; (b) use `df' from the GNU Fileutils package; or
+(c) use CVS, which is Free Software, instead of ClearCase.
+
 * Accessing remote files with ange-ftp hangs the MS-Windows version of Emacs.
 
 If the FTP client is the Cygwin port of GNU `ftp', this appears to be