Re: kern/37025

[Antti Kantee <pooka%cs.hut.fi@localhost>]

The following reply was made to PR kern/37025; it has been noted by GNATS.

From: Antti Kantee <pooka%cs.hut.fi@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/37025
Date: Mon, 12 Oct 2009 22:49:24 +0300

 I doubt -current is really any faster.  The fundamental problem is that
 smbfs does not support UBC and does writes in-context (at least based
 on my 2min glance at the code).  So if you do a lot of small writes,
 you end up paying a lot of RTT penalty.
 (well, ok, it shouldn't be quite *that* slow as what you report)
 
 You can mitigate this a little by using rump_smbfs, for which puffs
 provides UBC in front of smbfs.  People (like Matthias ;) have reported
 it being several times faster than a kernel mount for small I/O units.
 
 However, be warned that mount_smbfs does not correctly provide a stable
 vnode from a lookup.  Combined with UBC, this might cause some cache
 screwage in a multiuser environment.  (It is also probably quite easy
 to fix, but I didn't look into the SMB protocol.)