From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261801AbTDEEky (for ); Fri, 4 Apr 2003 23:40:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261800AbTDEEky (for ); Fri, 4 Apr 2003 23:40:54 -0500 Received: from franka.aracnet.com ([216.99.193.44]:42902 "EHLO franka.aracnet.com") by vger.kernel.org with ESMTP id S261801AbTDEEkw (for ); Fri, 4 Apr 2003 23:40:52 -0500 Date: Fri, 04 Apr 2003 20:52:02 -0800 From: "Martin J. Bligh" To: Andrea Arcangeli cc: Andrew Morton , 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: <9320000.1049518322@[10.10.2.4]> In-Reply-To: <20030405024414.GP16293@dualathlon.random> References: <20030404163154.77f19d9e.akpm@digeo.com> <12880000.1049508832@flay> <20030405024414.GP16293@dualathlon.random> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> I'm not convinced that we can't do something with nonlinear mappings for >> this ... we just need to keep a list of linear areas within the nonlinear >> vmas, and use that to do the objrmap stuff with. Dave and I talked about >> this yesterday ... we both had different terminology, but I think the >> same underlying fundamental concept ... I was calling them "sub-vmas" >> for each linear region within the nonlinear space. > > that's wasted memory IMHO, if you need nonlinear, you don't want to > waste further metadata, you only want to pin pages in the pagetables, > the 'window' over the pagecache (incidentally shm) Hold on a minute ... don't the rmap chains (which this would be replacing) waste rather more space than this anyway? I'd rather have it per linear area than per-page ... think of it as "shared rmap pte chains with offsets" if you like ;-) M.