Re: files.el: Once again impossible to turn off dir-settings

[Stefan Monnier]

>>> (setq vc-ignore-dir-regexp
>>> "\\`\\([\\/][\\/]\\|/net/\\|/home/\\|/afs/\\)\\'")
>>> Notice the addition of /home above  -- in my case /home is nfs
>>> mounted.
>> 
>> NFS mounting as such is normally not a problem.  So could you explain
>> exactly how is /home mounted?  Is it an autofs mount?  Do accesses to
>> /home/foobar automatically trigger access to some network server (even
>> if /home/foobar doesn't actually exist)?

> I don't know if this is what T. V. Raman is using, but I have experience
> of a setup where moving up the directory hierachy eventually leads to
> extreme slowness.  When (say) your home directory is mounted on AFS (a
> distributeed network file system), moving up the AFS file hierachy
> eventually brings you to the /afs root directory.  This directory is
> populated by literally thousands of files, each of which on a different
> server (each is a different AFS cell).

Indeed.  Which is why /afs is handled specially in
locate-dominating-stop-dir-regexp.  With NFS this problem normally
doesn't happen.

> Doing something like `ls' in this directory can take minutes.

dir-settings (and VC) doesn't use the equivalent of `ls' (aka
directory-files).  Instead it looks specifically for the few files that
could matter (e.g. CVS/Entries, .dit-settings.el, ...).  This can make
a very large difference.

> (I don't use this setup anymore, though; this was on a campus network
> where AFS was widely used.)

Yes, I've used AFS as well.  Neat thing (other than Kerberos whose
timeouts I don't like).


        Stefan