From: "NeilBrown" Subject: Re: [PATCH] NFS: Add acreg{min,max} and acdir{min, max} in milliseconds Date: Tue, 16 Jun 2009 09:08:04 +1000 (EST) Message-ID: <3786d1f06aae533fa82740d68985fd50.squirrel@neil.brown.name> References: <200906091832.50633.agud@akamai.com> <1244636844.24750.23.camel@heimdal.trondhjem.org> <4A300CE3.8080502@akamai.com> <025BEFCD-2F56-4E29-99F9-1939867B48A7@fys.uio.no> <4A316814.7030609@akamai.com> <1244754888.5047.132.camel@heimdal.trondhjem.org> <4A32ACDB.90802@akamai.com> <1244836259.19533.19.camel@heimdal.trondhjem.org> <4A32CD5D.2070502@akamai.com> <1244846673.32257.69.camel@heimdal.trondhjem.org> <4A36D0D1.3000904@akamai.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: "Trond Myklebust" , "linux-nfs@vger.kernel.org" , "Steve Dickson" , "gud-OYTqUY/oFF8@public.gmane.org" , "Uhlenkott, Jason" To: "Amit Gud" Return-path: Received: from cantor2.suse.de ([195.135.220.15]:57535 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbZFOXIN (ORCPT ); Mon, 15 Jun 2009 19:08:13 -0400 In-Reply-To: <4A36D0D1.3000904@akamai.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, June 16, 2009 8:53 am, Amit Gud wrote: > Trond Myklebust wrote: >> It boils down to this: I'm extremely reluctant to get into an arms race >> of adding ever more mount options for increasingly finer-tuned attribute >> cache timeouts. While such an option may meet _your_ machine room >> requirements here and now, it becomes tiresome over the years as >> machines gain power, and people first start lobbying for millisecond >> timeouts, then microseconds, nanoseconds, pico... in order to catch up. >> > > It only makes sense to make machines more powerful and put that power to > optimum use. If keeping up with increased resolution is an issue, you > think something like "-o unit=ms acregmin=..." would be better? 'unit' > can apply to all the time related options defaulting to seconds. Wasn't this problem solved hundreds of years ago by the invention of the decimal point :-) -o acregmin=0.0012 Write the code to use as much precision as makes sense given the value of HZ - and round up. No new mount options. NeilBrown