From: Chris Penney <cpenney@gmail.com>
Subject: Re: NFS Client Performance Question
Date: Wed, 13 Jul 2005 14:55:57 -0400
Message-ID: <111aefd05071311553ac3d52a@mail.gmail.com>
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To: "Lever, Charles" <Charles.Lever@netapp.com>
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The Itanium page size is 16k (unless I'm mistaken) and the r/wsize is
32k so can that still be it?  Or are you saying that it is because the
size of the write is only 4k?

   Chris

On 7/13/05, Lever, Charles <Charles.Lever@netapp.com> wrote:
> hi chris-
>=20
> take a look at the NFS faq (http://nfs.sourceforge.net) i believe this
> issue is addressed there.
>=20
> the problem is your itanium uses pages larger than your r/wsize setting,
> which forces the client into synchronous I/O mode for NFS.  some
> possible workarounds:
>=20
> 1.  upgrade to a late model 2.6 kernel where this is fixed
>=20
> 2.  reduce the page size on your client system
>=20
> 3.  increase the r/wsize to something larger than your page size
>=20
> 4.  compile your client with a larger maximum transfer size so you can
> do 3.
>=20
> the goal is to have r/wsize be equal to or greater than your client's
> page size.
>=20
> > -----Original Message-----
> > From: Chris Penney [mailto:cpenney@gmail.com]
> > Sent: Wednesday, July 13, 2005 2:30 PM
> > To: nfs@lists.sourceforge.net
> > Subject: [NFS] NFS Client Performance Question
> >
> >
> > I have a large smp SGI Itanium box box running a 2.4.21 kernel and I'm
> > getting fairly bad NFS performance, esp. when doing random writes to
> > an unloaded NFS server.  The box is rather busy doing computation and
> > a lot of i/o to /tmp; however, there is little network i/o (<100
> > KB/s).  I use iozone with the following options to test "-c -e -i 2 -w
> > -s 16m" and use an unloaded Sun NFS server (same performance results
> > with Linux NFS servers, but they are all under load so I test with the
> > Sun).  I only get ~2.5MB/s using the above test.  I found an Intel box
> > still running a 2.4.20 kernel and it gets 15MB/s.  On a 2.6 kernel box
> > the rate jumps to 46MB/s (nice work).
> >
> > I did some sniffing on the Sun and noticed that the problem Itanium
> > system was not doing async writes (snips are from the start of the
> > write test):
> >
> > [snip]
> > redhat -> server NFS C WRITE3 FH=3D40E5 at 1478656 for 4096 (ASYNC)
> > server -> redhat NFS R WRITE3 OK 4096 (ASYNC)
> > redhat -> server NFS C WRITE3 FH=3D40E5 at 1179648 for 4096 (ASYNC)
> > [snip]
> > itanium -> server NFS C WRITE3 FH=3D40E5 at 4239360 for 4096 (FSYNC)
> > server -> server NFS R WRITE3 OK 4096 (FSYNC)
> > server -> server NFS C WRITE3 FH=3D40E5 at 15101952 for 4096 (FSYNC)
> > [snip]
> >
> > The client mount options are:
> >    rw,nosuid,bg,hard,intr,nfsvers=3D3,tcp,rsize=3D32768,wsize=3D32768
> >
> > So my question: Is the Itanium system not doing async nfs i/o because
> > nfract_sync has been exceeded due to local i/o to /tmp or is it
> > something else?  Is there anything I can do to improve NFS performance
> > on this box?
> >
> >    Chris
> >
> >
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