Re: [PATCH 4/5] NFSD: Remove NFSD_TCP kernel build option

[Frank van Maarseveen <frankvm@frankvm.com>]

On Tue, Feb 05, 2008 at 04:49:39PM +1100, Greg Banks wrote:
> Chuck Lever wrote:
> > On Feb 4, 2008, at 7:29 PM, Greg Banks wrote:
> >> Trond Myklebust wrote:
> >>> On Tue, 2008-02-05 at 11:19 +1100, Greg Banks wrote:
> >>>
> >>>> Chuck Lever wrote:
> >>>>
> >>>>> TCP support in the Linux NFS server is stable enough that we can
> >>>>> leave it
> >>>>> on always.  CONFIG_NFSD_TCP adds about 10 lines of code, and
> >>>>> defaults to
> >>>>> "Y" anyway.
> >>>>>
> >>>>> A run-time switch might be more appropriate if people feel they
> >>>>> would like
> >>>>> to disable NFSD's TCP support.
> >>>>>
> >>>>>
> >>>>>
> >>>> Looks good.
> >>>>
> >>>> Actually, I'd be inclined to go one step further and set UDP support
> >>>> off by default.
> >>>>
> >>>
> >>> That will break older clients.
> >>>
> >>>
> >> Hence the default, rather than removing the code entirely.
> >
> >
> > What might make sense is to remove NFSD_TCP, but add NFSD_UDP,
> > defaulting to Y.
> >
> > Then in a year or two we can change the default to N.
> >
> Fine by me.

Last time I checked (around 2.6.22) writing large files on NFSv3 over
UDP was 20% faster compared to TCP (Gb LAN with one switch connecting
all machines).

TCP and its timeout/retransmission behavior isn't always the best choice.

-- 
Frank