From: "Heflin, Roger A." <Roger.A.Heflin@conoco.com>
Subject: 2.4.19 NFSALL performance oddity
Date: Fri, 4 Oct 2002 16:45:14 -0500
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I am running some tests using 2.4.19 with all posted nfs patchs, =
everything is
being run sync.   All runs are with NFS3 over UDP.

I have noticed that the IO rates (writes) start slowly (about =
1.5MB/second) and
slowly build up to a peak of 2.5MB/second over several minutes, with the
test averaging 2.32 MB/second over a 2GB file write.  This is=20
with a server with Gigabit copper and the client with 100BT ethernet.  =20
No packets are being lost from what I can tell, on either the server or=20
the client, both machines are dual cpu with 2GB of ram and otherwise=20
unloaded.

The 2.2.19 client (with almost no NFS patches) runs about 3.98MB/second =
over
a 2GB file write, against the same 2.4.19 NFS server, and hits that rate =

almost immediately.

Using an older 2.4.19 NFS server (that I don't believe has any extra NFS
patches) gets a rate of 6.50 average over a 2GB file from
a 2.2.19 client and gets 2.00  MB/second average from one of the
original 2.4 test clients.

Both rsize and wsize are 8192, I have tried it with 32768 on at least
the 2.4 client side, but it does not appear to affect the above results.
I am tried with 32 and 64 nfsd and this did not appear to change
any of the results.   The rmem/wmem parameters have been upped
to 256K and did not appear to make any difference on the server.

The disk is locally capable of 20MB/second writes over a 4GB file, using
the same test as was used above.

Is there a way to make the IO start fast and stay fast?   What code =
could
I look at to see if I can affect the way this works?   Any parameters =
that
I could try changing that might improve things?

It appears to partially be client issue since the 2.2.19 NFS client is =
noticeably
faster, but since the older 2.4.19 server and the 2.2.19 client is even =
faster it
appears to also be a server issue.

So in summary:

2.2.19 -> 2.4.19 no patches -> 6.5MB/second
2.4.19nfsall -> 2.4.19 no patches ->  2.00 MB/second
2.2.19 -> 2.4.19 nfsall patch -> 3.98MB/second
2.4.19nfsall -> 2.4.19 nfsall patch -> 2.32 MB/second


				Roger


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