From: Krishna Kumar2 Subject: Re: NFS performance degradation of local loopback FS. Date: Mon, 30 Jun 2008 15:27:18 +0530 Message-ID: References: <76bd70e30806270706x7cbfd291l6cb6d0cc5e81771@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: "J. Bruce Fields" , "Benny Halevy" , chucklever@gmail.com, linux-nfs@vger.kernel.org, "Peter Staubach" To: chucklever@gmail.com Return-path: Received: from e28smtp06.in.ibm.com ([59.145.155.6]:47667 "EHLO e28esmtp06.in.ibm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754779AbYF3J62 (ORCPT ); Mon, 30 Jun 2008 05:58:28 -0400 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by e28esmtp06.in.ibm.com (8.13.1/8.13.1) with ESMTP id m5U9w5hu029261 for ; Mon, 30 Jun 2008 15:28:05 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m5U9us2n962708 for ; Mon, 30 Jun 2008 15:26:54 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.13.1/8.13.3) with ESMTP id m5U9w4j4026599 for ; Mon, 30 Jun 2008 15:28:05 +0530 In-Reply-To: <76bd70e30806270706x7cbfd291l6cb6d0cc5e81771-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: chucklever@gmail.com wrote on 06/27/2008 07:36:44 PM: > > But loopback is better than actual network traffic. > > What precisely do you mean by that? Sorry I was not clear. I meant that the loopback will be better than actual traffic between different server/client. > You are testing with the client and server on the same machine. Is > the loopback mount over the lo interface, but you mount the machine's > actual IP address for the "network" test? Actually isn't that the same? I am using localhost in any case. > It would be interesting to compare a network-only performance test > (like iPerf) for loopback and for going through the NIC. iperf (one thread, 64K I/O size, 30 secs): NIC: 445 MB/s Loopback: 735 MB/s In retrospect, for disk I/O: /local: 39 MB/s /nfs (loopback): 29 MB/s (25.5% drop) /nfs (from a real server): 27 MB/s (30.5% drop, only point is that this is a different disk on a different system and it doesn't make much sense to compare this to /local). Thanks, - KK