Message-ID: <400D902D.8080607@portrix.net>
Date: Tue, 20 Jan 2004 21:31:41 +0100
From: Jan Dittmer <j.dittmer@portrix.net>
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To: jlnance@unity.ncsu.edu
CC: Trond Myklebust <trond.myklebust@fys.uio.no>, linux-kernel@vger.kernel.org,
       cmp@synopsys.com
Subject: Re: Awful NFS performance with attached test program
References: <20040119211649.GA20200@ncsu.edu> <1074549226.1560.59.camel@nidelv.trondhjem.org> <20040120132803.GA2830@ncsu.edu>
In-Reply-To: <20040120132803.GA2830@ncsu.edu>
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jlnance@unity.ncsu.edu wrote:
> On Mon, Jan 19, 2004 at 04:53:46PM -0500, Trond Myklebust wrote:
> 
> 
>>So you are surprised that writing the same dataset by putting one
>>integer onto each kernel page takes much more time than placing the
>>entire dataset onto just a few kernel pages? 'cos I'm not...
> 
> 
> I must admit that I am.  I could see that it would take somewhat longer
> because a logicial way for the kernel to implement this would be as a
> read-modify-write operation.  So a 2X slowdown would not supprise me.
> But the slowdown is more than 10X, and that does.
> 
> Also, for what its worth, Solaris performs like this:
> 
>     flame> ./a.out 
>     Creating file: 3.886 seconds
>     Updating file: 1.259 seconds
> 
> While Linux performs like this:
> 
>     jesse> ./a.out
>     Creating file: 43.042 seconds
>     Updating file: 555.796 seconds

My Client (2.6.1-mm2) against my server (2.6.1-bk6) is significantly faster:

./nfstest
Creating file: 11.607 seconds
Updating file: 35.885 seconds

Note the increase of the factor 3 only instead of 10.
nfs mount options: 
rw,hard,intr,rsize=8192,wsize=8192,timeo=30,retrans=10,tcp

Thanks,

Jan

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