[prev in list] [next in list] [prev in thread] [next in thread] 

List:       freebsd-net
Subject:    Re: slow writes on nfs with bge devices
From:       Kelly Yancey <kbyanc () posi ! net>
Date:       2007-01-25 1:02:35
Message-ID: 20070124164949.P16327 () gateway ! posi ! net
[Download RAW message or body]

On Sun, 21 Jan 2007, Max Laier wrote:

> On Sunday 21 January 2007 13:25, Bruce Evans wrote:
> > On Sun, 21 Jan 2007, Max Laier wrote:
> > > On Sunday 21 January 2007 07:25, Bruce Evans wrote:
> > >> nfs writes much less well with bge NICs than with other NICs (sk,
> > >> fxp,
> > >
> > > Do you use hardware checksumming on the bge?  There is an XXX in
> > > bge_start_locked() that looks a bit suspicious to me.
> >
> > I use the default for that.  Wouldn't checksum problems show up as
> > errors somwhere?
>
> Did you look at the code in question?  It is concerned with fragmented
> packet chains (which NFS over UDP usually generated) and only commits to
> sending them, if there are enough descriptors available at once.  This
> can easily explain burstyness.
>
> Can you just try to disable the delayed checksums via "ifconfig -txcsum"?
> Should be an easy enough test.
>

  I realize that Bruce has already identified the problem as being with
the cabling, however I wanted to add a warning that disabling hardware
checksums for bge cards is not a good idea.  You can find my analysis of
data corruption bugs caused by using bge cards without checksum
offloading in the archives:
http://lists.freebsd.org/pipermail/freebsd-net/2004-January/002530.html

  Kelly

-- 
Kelly Yancey  -  kbyanc@posi.net | kelly@nttmcl.com
_______________________________________________
freebsd-net@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
[prev in list] [next in list] [prev in thread] [next in thread]