From: Trond Myklebust Subject: Re: [PATCH] NFS: Add acreg{min,max} and acdir{min,max} in milliseconds Date: Wed, 10 Jun 2009 20:11:04 -0400 Message-ID: <025BEFCD-2F56-4E29-99F9-1939867B48A7@fys.uio.no> References: <200906091832.50633.agud@akamai.com> <1244636844.24750.23.camel@heimdal.trondhjem.org> <4A300CE3.8080502@akamai.com> Mime-Version: 1.0 (iPhone Mail 5H11) Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes Cc: "linux-nfs@vger.kernel.org" , Steve Dickson , "gud-OYTqUY/oFF8@public.gmane.org" , "Uhlenkott, Jason" To: Amit Gud Return-path: Received: from mail-out2.uio.no ([129.240.10.58]:44948 "EHLO mail-out2.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752281AbZFKALL (ORCPT ); Wed, 10 Jun 2009 20:11:11 -0400 In-Reply-To: <4A300CE3.8080502@akamai.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Jun 10, 2009, at 15:43, Amit Gud wrote: > Trond Myklebust wrote: >> On Tue, 2009-06-09 at 18:32 -0700, Amit Gud wrote: >>> This patch adds 4 new NFS mount options(acdirminms, acdirmaxms, >>> acregminms, >>> acregmaxms) converting already existing one into a millisecond >>> resolution >>> instead of seconds. >>> >>> Also, modifies the mountstats output to milliseconds instead of >>> seconds. >> >> Why, exactly, do you need to control cache timeouts down to the >> millisecond level? >> > > The problem is to make the updates visible from one client to the > other > in less than a second and turning off caching entirely has an > unacceptably high penalty. Specifics, please: updates of what, exactly? Are we talking attributes, data or directory contents? What is your application, and why does 1ms constitute an acceptable caching timeout, while 1s does not? Trond