From: Krishna Kumar2 Subject: Re: NFS performance degradation of local loopback FS. Date: Thu, 19 Jun 2008 15:28:06 +0530 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linux-nfs@vger.kernel.org To: Krishna Kumar2 Return-path: Received: from e28smtp05.in.ibm.com ([59.145.155.5]:35764 "EHLO e28esmtp05.in.ibm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757423AbYFSJ7S (ORCPT ); Thu, 19 Jun 2008 05:59:18 -0400 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by e28esmtp05.in.ibm.com (8.13.1/8.13.1) with ESMTP id m5J9wkGE005003 for ; Thu, 19 Jun 2008 15:28:46 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m5J9wSFO1196168 for ; Thu, 19 Jun 2008 15:28:28 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.13.1/8.13.3) with ESMTP id m5J9wj0a014265 for ; Thu, 19 Jun 2008 15:28:45 +0530 Received: from d23ml172.in.ibm.com (d23ml172.in.ibm.com [9.124.105.37]) by d28av04.in.ibm.com (8.13.1/8.12.11) with ESMTP id m5J9wjYb014262 for ; Thu, 19 Jun 2008 15:28:45 +0530 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: > 200 processes: By "200 processes", I meant 200 dd's, each reading from /dev/zero and writing to a file on the filesystem. The script "nfs" was run twice, first with a local filesystem and the second time with the same filesystem NFS mounted. Thanks, - KK linux-nfs-owner@vger.kernel.org wrote on 06/19/2008 12:16:23 PM: > > Hi, > > I am running 2.6.25 kernel on a [4 way, 3.2 x86_64, 4GB] system. The test > is doing I/O on a local ext3 filesystem, and measuring the bandwidth, and > then NFS mounting the filesystem loopback on the same system. I have > configured 64 nfsd's to run. The test script is attached at the bottom. > > My configuration is: > /dev/some-local-disk : /local > NFS mount /local : /nfs > > The result is: > 200 processes: > /local: 108000 KB/s > /nfs: 66000 KB/s: Drop of 40% > > 300 processes (KB/s): > /local: 112000 KB/s > /nfs: 57000 KB/s: Drop of 50% > > I am not using any tuning, though I have tested with both > sunrpc.tcp_slot_table_entries=16 & 128 > > Is this big a drop expected for a loopback NFS mount? Any > feedback/suggestions are very > appreciated. > > Thanks, > > - KK > > (See attached file: nfs)[attachment "nfs" deleted by Krishna Kumar2/India/IBM]