From: "Lever, Charles" <Charles.Lever@netapp.com>
Subject: RE: NFS and tinygrams
Date: Thu, 21 Oct 2004 10:47:14 -0700
Sender: nfs-admin@lists.sourceforge.net
Message-ID: <482A3FA0050D21419C269D13989C61130435E9E2@lavender-fe.eng.netapp.com>
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Cc: "Linux NFS Mailing List" <nfs@lists.sourceforge.net>
To: "Dan Stromberg" <strombrg@dcs.nac.uci.edu>
Errors-To: nfs-admin@lists.sourceforge.net

what's a "tinygram" ?

do you mean the NFS write requests aren't all "wsize" bytes?  or do you
mean the TCP layer is segmenting into small IP packets?  these are two
separate layers, and do not interact.

> -----Original Message-----
> From: Dan Stromberg [mailto:strombrg@dcs.nac.uci.edu]=20
> Sent: Thursday, October 21, 2004 1:05 PM
> To: Linux NFS Mailing List
> Cc: Dan Stromberg
> Subject: [NFS] NFS and tinygrams
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> We have a series of test transfers going, where we are=20
> shuttling data from GFS->NFS V3 over UDP->NFS V3 over TCP->Lustre.
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> On the NFS V3 over TCP link, we're seeing a lot of tinygrams,=20
> despite having 8K NFS block sizes turned on, and jumbo=20
> packets enabled (9000 byte MTU).
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> The GFS machine runs Redhat 9, the first NFS server also runs=20
> Redhat 9.=20
> The machine copying from NFS to NFS is running AIX 5.1.  The=20
> machine copying NFS to Lustre is running RHEL 3.
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> I didn't check on the packet sizes of the other legs of the transfer.
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> I've verified that we do have jumbo packets being used some=20
> of the time, on that AIX 5.1 -> RHEL 3 hop.  However, we're=20
> still getting a pretty large percentage of tinygrams.
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> Is there any way of cutting down on the tinygrams, to more=20
> effectively utilize our large MTU?  Is there perhaps any sort=20
> of "intent based" packetizing in standard implementations of=20
> NFS on Redhat 9, AIX 5.1, and/or RHEL 3?
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> (Yes, we could short circuit the AIX 5.1 part of the=20
> transfer, and that Would make things faster, but it Wouldn't=20
> test what we need to test!)
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> Thanks!
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> --=20
> Dan Stromberg DCS/NACS/UCI <strombrg@dcs.nac.uci.edu>
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