From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262883AbTDFJSO (for ); Sun, 6 Apr 2003 05:18:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262885AbTDFJSO (for ); Sun, 6 Apr 2003 05:18:14 -0400 Received: from to-telus.redhat.com ([207.219.125.105]:28665 "EHLO touchme.toronto.redhat.com") by vger.kernel.org with ESMTP id S262883AbTDFJSN (for ); Sun, 6 Apr 2003 05:18:13 -0400 Date: Sun, 6 Apr 2003 05:29:43 -0400 From: Benjamin LaHaise To: Andrea Arcangeli Cc: Andrew Morton , mbligh@aracnet.com, mingo@elte.hu, hugh@veritas.com, dmccr@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: objrmap and vmtruncate Message-ID: <20030406052943.B4440@redhat.com> References: <20030404163154.77f19d9e.akpm@digeo.com> <12880000.1049508832@flay> <20030405024414.GP16293@dualathlon.random> <20030404192401.03292293.akpm@digeo.com> <20030405040614.66511e1e.akpm@digeo.com> <20030405163003.GD1326@dualathlon.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20030405163003.GD1326@dualathlon.random>; from andrea@suse.de on Sat, Apr 05, 2003 at 06:30:03PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 05, 2003 at 06:30:03PM +0200, Andrea Arcangeli wrote: > > I'm not questioning during paging rmap is more efficient than objrmap, > but your argument about rmap having lower complexity of objrmap and that > rmap is needed is wrong. The fact is that with your 100 mappings per > each of the 100 tasks case, both algorithms works in O(N) where N is > the number of the pagetables mapping the page. No difference in Small mistake on your part: there are two different parameters to that: objrmap is O(N) where N is the number of vmas, and regular rmap is O(M) where M is the number of currently mapped ptes. M <= N and is frequently less for sparsely resident pages (ie in things like executables). -ben