From mboxrd@z Thu Jan 1 00:00:00 1970 From: "J. Bruce Fields" Subject: Re: high latency NFS Date: Wed, 30 Jul 2008 23:15:12 -0400 Message-ID: <20080731031512.GA26203@fieldses.org> References: <200807241311.31457.shuey@purdue.edu> <20080730192110.GA17061@fieldses.org> <4890DFC7.3020309@cse.unsw.edu.au> <200807302235.50068.shuey@purdue.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Shehjar Tikoo , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, rees@citi.umich.edu, aglo@citi.umich.edu To: Michael Shuey Return-path: Received: from mail.fieldses.org ([66.93.2.214]:49767 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754513AbYGaDP0 (ORCPT ); Wed, 30 Jul 2008 23:15:26 -0400 In-Reply-To: <200807302235.50068.shuey-olO2ZdjDehc3uPMLIKxrzw@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Jul 30, 2008 at 10:35:49PM -0400, Michael Shuey wrote: > Thanks for all the tips I've received this evening. However, I figured out > the problem late last night. :-) > > I was only using the default 8 nfsd threads on the server. When I raised > this to 256, the read bandwidth went from about 6 MB/sec to about 95 > MB/sec, at 100ms of netem-induced latency. So this is yet another reminder that someone needs to implement some kind of automatic tuning of the number of threads. I guess the first question is what exactly the policy for that should be? How do we decide when to add another thread? How do we decide when there are too many? --b.