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Date: Fri, 23 Mar 2012 07:49:13 -0400
From: Jim Rees <rees@umich.edu>
To: Vivek Trivedi <vtrivedi018@gmail.com>
Cc: "Myklebust, Trond" <Trond.Myklebust@netapp.com>, linux-nfs@vger.kernel.org,
        linux-kernel@vger.kernel.org, Namjae Jeon <linkinjeon@gmail.com>,
        amit.sahrawat83@gmail.com
Subject: Re: NFS: low read/stat performance on small files
Message-ID: <20120323114913.GB24489@umich.edu>
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Vivek Trivedi wrote:

  204800 bytes (200.0KB) copied, 0.027074 seconds, 7.2MB/s
  Read speed for 200KB file is 7.2 MB

  104857600 bytes (100.0MB) copied, 9.351221 seconds, 10.7MB/s
  Read speed for 100MB file is 10.7 MB
  
  As you see read speed for 200KB file is only 7.2MB/sec while it is
  10.7 MB/sec when we read 100MB file.
  Why there is so much difference in read performance ?
  Is there any way to achieve high read speed for small files ?

That seems excellent to me.  204800 bytes at 11213252 per sec would be 18.2
msec, so your per-file overhead is around 9 msec.  The disk latency alone
would normally be more than that.