From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750930AbXCSUpK (ORCPT ); Mon, 19 Mar 2007 16:45:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752104AbXCSUpK (ORCPT ); Mon, 19 Mar 2007 16:45:10 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:38945 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750930AbXCSUpI (ORCPT ); Mon, 19 Mar 2007 16:45:08 -0400 Message-ID: <45FEF5BC.90809@oracle.com> Date: Mon, 19 Mar 2007 13:42:36 -0700 From: Randy Dunlap User-Agent: Thunderbird 1.5.0.5 (X11/20060719) MIME-Version: 1.0 To: Andrew Morton CC: "H. Peter Anvin" , "J.H." , kernel list Subject: Re: [PATCH] sysctl: vfs_cache_divisor References: <20061214223718.GA3816@elf.ucw.cz> <20061216094421.416a271e.randy.dunlap@oracle.com> <20061216095702.3e6f1d1f.akpm@osdl.org> <458434B0.4090506@oracle.com> <1166297434.26330.34.camel@localhost.localdomain> <20061219063413.GI24090@1wt.eu> <1166511171.26330.120.camel@localhost.localdomain> <20070106103331.48150aed.randy.dunlap@oracle.com> <459FF60D.7080901@zytor.com> <1168112266.2821.2.camel@entropy> <20070106121301.d07de0c9.akpm@osdl.org> <45A0041F.4060903@zytor.com> <20070319122740.286f602e.randy.dunlap@oracle.com> <20070319133613.9f4881db.akpm@linux-foundation.org> In-Reply-To: <20070319133613.9f4881db.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > On Mon, 19 Mar 2007 12:27:40 -0700 > Randy Dunlap wrote: > >> +The default vfs_cache_divisor value is 100 (like percent). However, for >> +extremely large systems where a value of vfs_cache_pressure of less than >> +1 percent is desirable, using a larger vfs_cache_divisor enables this wanted >> +characteristic. > > The one-percent-granularity problem also applies to /proc/sys/vm/*dirty* > and possibly other things. So any fix we do should be applicable to those > as well. > > And I'm not really sure how we should do this. I do think that we should > change the kernel so these knobs are internally higher-resolution. So, for > example, we switch all the logic so that instead of these variables > representing 1/100th, they instead represent 1/1000000th, for example. > > Then, we change the top-level /proc handler to do the 1/100th <-> 1/1000000th > conversion. So the rest of the kernel doesn't have to know about it. > > The we duplicate all the relevant /proc knobs: > > cat /proc/sys/vm/dirty_ratio > 30 > cat /proc/sys/vm/hires-dirty_ratio/ > 300000 > > Or we do something else ;) Sounds better. I wasn't very keen on the userspace interface that this exposed. Will look at those. -- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***