Subject: Re: 2.6.15.1: persistent nasty hang in sync_page killing NFS
	(ne2k-pci / DP83815-related?), i686/PIII
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Nix <nix@esperi.org.uk>
Cc: linux-kernel@vger.kernel.org, thockin@hockin.org
In-Reply-To: <8764o23j0s.fsf@amaterasu.srvr.nix>
References: <87fyn8artm.fsf@amaterasu.srvr.nix>
	 <1138499957.8770.91.camel@lade.trondhjem.org>
	 <87slr79knc.fsf@amaterasu.srvr.nix>  <8764o23j0s.fsf@amaterasu.srvr.nix>
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Date: Sun, 29 Jan 2006 15:21:15 -0500
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On Sun, 2006-01-29 at 19:56 +0000, Nix wrote:
> Further info, possibly in support of your suggestion, possibly not: the
> problem does *not* occur with NFS-over-TCP. So it's specific to UDP,
> this hardware (perhaps motherboard or network card, see the .config
> diff), *and* NFS. Other UDP stuff (e.g. DNS) gets through fine in both
> directions; NFS works with TCP; and the whole lot worked before the
> hardware was changed.

If it works with TCP but not UDP, then the problem is usually either a
NIC driver issue, or a lossy network.
Comparing with DNS is not really useful, because NFS over UDP uses much
larger packet sizes (32k usually) which causes heavy use of
fragmentation.

Cheers,
 Trond

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