From: Chuck Lever Subject: Re: iostat "await" like counter for measuring nfs latency Date: Thu, 29 Jul 2010 11:53:10 -0400 Message-ID: <4C51A3E6.4000101@oracle.com> References: <1280244478.2981.3.camel@heimdal.trondhjem.org> <4C4FFC2B.4020906@Voltaire.com> <4C506B78.7040108@oracle.com> <4C508330.8010303@orange.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Cc: Or Gerlitz , Trond Myklebust , linux-nfs@vger.kernel.org To: Sebastien Godard Return-path: Received: from rcsinet10.oracle.com ([148.87.113.121]:36434 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754416Ab0G2PyQ (ORCPT ); Thu, 29 Jul 2010 11:54:16 -0400 In-Reply-To: <4C508330.8010303@orange.fr> Sender: linux-nfs-owner@vger.kernel.org List-ID: On 07/28/10 03:21 PM, Sebastien Godard wrote: > On 07/28/2010 07:40 PM, Chuck Lever wrote: >> >> On 07/28/10 05:45 AM, Or Gerlitz wrote: >>> Trond Myklebust wrote: >>>> On Tue, 2010-07-27 at 13:07 +0300, Or Gerlitz wrote: >>>>> Doing some iscsi and nfs performance testing, I realized that >>>>> iostat(1) >>>>> doesn't support an "await" like counter for measuring nfs latency. >>>>> Can tracking nfs latency be done in other means? is there a plan to >>>>> extend the nfs iostats code to include such/similar counter? >>> >>>> The information is already available in /proc/self/mountstats. It is up >>>> to iostat to start using it. >>> >>> Sebastian, is there a plan to support await like counter in sysstat? >>> >>> I didn't find a source repository (is there an open one? where?) so >>> downloaded the latest code (version 9.1.3) drop from the website and >>> couldn't see there such a counter, am I missing something? >> >> There are Python scripts in nfs-utils that report the statistics in >> /proc/self/mountstats. Nobody really likes the file format of >> /proc/self/mountstats, so the plan is to move these, at some point, to >> someplace where perf can report them. >> >> At that point, iostat support would also be nice. >> > > I'm ready to accept a patch that would add an await like counter to > measure NFS latency. What is await, precisely? And, by "NFS latency" do you mean read/write latency or something else? For NFS, even stat() can require server interaction (ie is not served from the system's local memory) > BTW beginning with sysstat version 9.1.3, there is a specific command > ("nfsiostat") aimed at displaying stats for network filesystems.