From: "Lever, Charles" <Charles.Lever@netapp.com>
Subject: RE: Re: [PATCH] Smooth out NFS client writeback
Date: Wed, 29 Jun 2005 07:25:41 -0700
Message-ID: <482A3FA0050D21419C269D13989C611307CF4CE6@lavender-fe.eng.netapp.com>
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Cc: "Trond Myklebust" <trond.myklebust@fys.uio.no>,
	<nfs@lists.sourceforge.net>
To: "Peter Staubach" <staubach@redhat.com>,
	"Shantanu Goel" <sgoel01@yahoo.com>
Sender: nfs-admin@lists.sourceforge.net
Errors-To: nfs-admin@lists.sourceforge.net

hi peter-

> On Solaris, at least with UFS as the underlying file system,=20
> the COMMIT
> operations are processed by looking through the entire cached=20
> page list
> or by doing page lookup operations on each individual page. =20
> If the entire
> file is specified, ie. len =3D 0, then the page list is walked.=20
>  If a range
> is specified, then just the pages within the range are looked up.
>=20
> Specifying the range can result in significantly less CPU=20
> overhead on the
> server.  This is why the NFSv3 COMMIT operation has a range=20
> which can be specified...  :-)

a server CPU inefficiency hardly qualifies as a client bug.  in the most
common cases where the client is creating and writing to a file, then
closing with a COMMIT(0,0) request, the server should be changed to
behave in a more efficient manner.

in other words, i think the client should optimize the number of
requests on the wire, and the server should optimize for using its CPU
and disks most efficiently.  i haven't looked closely at shantanu's
patch, but i'm a little leary of the change if it means more wire
operations are generated than before.


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