From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993056AbXDTR51 (ORCPT ); Fri, 20 Apr 2007 13:57:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2993078AbXDTR51 (ORCPT ); Fri, 20 Apr 2007 13:57:27 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:38418 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2993056AbXDTR50 (ORCPT ); Fri, 20 Apr 2007 13:57:26 -0400 Date: Fri, 20 Apr 2007 10:57:25 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: William Lee Irwin III cc: Mel Gorman , linux-kernel@vger.kernel.org, Peter Zijlstra , Nick Piggin , Andi Kleen , Paul Jackson , Dave Chinner Subject: Re: [RFC 7/8] Enhance ramfs to support higher order pages In-Reply-To: <20070420171928.GA2986@holomorphy.com> Message-ID: References: <20070419163504.11948.58487.sendpatchset@schroedinger.engr.sgi.com> <20070419163540.11948.51549.sendpatchset@schroedinger.engr.sgi.com> <20070420134226.GA16878@skynet.ie> <20070420144726.GI31925@holomorphy.com> <20070420171118.GZ2986@holomorphy.com> <20070420171928.GA2986@holomorphy.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Apr 2007, William Lee Irwin III wrote: > On Fri, 20 Apr 2007, William Lee Irwin III wrote: > >> The core VM can do that but the hugetlb architectural code can't fall > >> back to smaller page sizes. It also should not be put into a situation > >> where it needs to do so given the semantics it must honor. > > On Fri, Apr 20, 2007 at 10:15:00AM -0700, Christoph Lameter wrote: > > Wel we could potentially add a handle_pmd_fault to the vm...? > > Unconscionably foul. I guess x86-uber-alles pagetables in the core vm > is the Linux way, though. Yes sadly true. The alternative is to add a page table abstraction layer first. > On Fri, 20 Apr 2007, William Lee Irwin III wrote: > >> Also, the final assertion is inaccurate. Fault handlers must instantiate > >> pages of order mapping->order when faulting in a page of a file with > >> a given pagecache size. The semantics of faulting and mmap()'ing are > > On Fri, Apr 20, 2007 at 10:15:00AM -0700, Christoph Lameter wrote: > > Why? I agree that the page state of the higher order page must be updated > > consistently but one can use a pte to map a 4k chunk of a higher > > order page. > > Probably just terminological disagreement here. I was referring to > allocating the higher-order page from the fault path here, not mapping > it or a piece of it with a user pte. Ah. Okay. I have some dysfunctional patches here that implement mmap support. Would you be willing to take care of that aspect of things? Then I can focus on the other VM pieces. I am going to post them following this message. These are an absolute mess. They do not compile etc etc.