From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751134AbXCDABR (ORCPT ); Sat, 3 Mar 2007 19:01:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751149AbXCDABR (ORCPT ); Sat, 3 Mar 2007 19:01:17 -0500 Received: from mx1.redhat.com ([66.187.233.31]:36533 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751134AbXCDABQ (ORCPT ); Sat, 3 Mar 2007 19:01:16 -0500 Message-ID: <45EA0C3D.1010001@redhat.com> Date: Sat, 03 Mar 2007 19:01:01 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: Andrew Morton CC: linux-kernel@vger.kernel.org Subject: Re: userspace pagecache management tool References: <20070303122935.f1ab0067.akpm@linux-foundation.org> <45E9DD4A.2060806@redhat.com> <20070303131204.6706a95c.akpm@linux-foundation.org> <45E9E910.2070804@redhat.com> <20070303140744.b22699dd.akpm@linux-foundation.org> <45E9F5DA.2070708@redhat.com> <20070303145221.2a42cc0f.akpm@linux-foundation.org> In-Reply-To: <20070303145221.2a42cc0f.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > On Sat, 03 Mar 2007 17:25:30 -0500 Rik van Riel wrote: > >> backup program > > A suitable policy for a backup program would probably be to invalidate any > output file(s) and to invalidate those pages of the input files which were > not in cache when the backup program first opened those files. That way > the backup program will have no effect on the cache state, except for the > race situation where someone read an uncached file while the backup program > was reading from it too. The use-once policy we have in the kernel should work perfectly fine for backups. All we need to do is actually honor the accessed bit on active page cache pages, instead of flushing them onto the inactive list. What am I overlooking? > This can be added in an hour or two with no kernel changes (use mincore). mincore only works for mmaped areas, we'd need an fincore to work with file handles. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic.