Return-Path: linux-nfs-owner@vger.kernel.org Received: from smtp.mail.umich.edu ([141.211.14.82]:57652 "EHLO hellskitchen.mr.itd.umich.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758153Ab2CWLtR (ORCPT ); Fri, 23 Mar 2012 07:49:17 -0400 Date: Fri, 23 Mar 2012 07:49:13 -0400 From: Jim Rees To: Vivek Trivedi Cc: "Myklebust, Trond" , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Namjae Jeon , amit.sahrawat83@gmail.com Subject: Re: NFS: low read/stat performance on small files Message-ID: <20120323114913.GB24489@umich.edu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: 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.