From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932878AbXCCVMP (ORCPT ); Sat, 3 Mar 2007 16:12:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932931AbXCCVMP (ORCPT ); Sat, 3 Mar 2007 16:12:15 -0500 Received: from smtp.osdl.org ([65.172.181.24]:46272 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932878AbXCCVMO (ORCPT ); Sat, 3 Mar 2007 16:12:14 -0500 Date: Sat, 3 Mar 2007 13:12:04 -0800 From: Andrew Morton To: Rik van Riel Cc: linux-kernel@vger.kernel.org Subject: Re: userspace pagecache management tool Message-Id: <20070303131204.6706a95c.akpm@linux-foundation.org> In-Reply-To: <45E9DD4A.2060806@redhat.com> References: <20070303122935.f1ab0067.akpm@linux-foundation.org> <45E9DD4A.2060806@redhat.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 03 Mar 2007 15:40:42 -0500 Rik van Riel wrote: > Andrew Morton wrote: > > > It is to address the "waah, backups fill my memory with pagecache" and the > > "waah, updatedb swapped everything out" and the "waah, copying a DVD > > gobbled all my memory" problems. > > By removing pressure from the page cache, you'll only allow updatedb > to grow the inode and dentry caches larger than before. Well duh. That's a two-order-of-magnitude lesser problem and only affects one of many problematic workloads. > I am sick and tired of the "this is hard, let userspace do it" attitude. Anything you try to do in-kernel will catastrophically screw up some workloads. You don't have a chance of getting this right. You are the kernel. The user just read an entire kernel tree. You face a binary decision: do you cache that tree or do you not? Your time starts now. What is your answer?