Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261418AbUDHB4l (ORCPT ); Wed, 7 Apr 2004 21:56:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261422AbUDHB4l (ORCPT ); Wed, 7 Apr 2004 21:56:41 -0400 Received: from ozlabs.org ([203.10.76.45]:64485 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S261418AbUDHB4j (ORCPT ); Wed, 7 Apr 2004 21:56:39 -0400 Date: Thu, 8 Apr 2004 11:50:43 +1000 From: David Gibson To: Andi Kleen Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org, anton@samba.org, paulus@samba.org, linuxppc64-dev@lists.linuxppc.org Subject: Re: RFC: COW for hugepages Message-ID: <20040408015043.GA20320@zax> Mail-Followup-To: David Gibson , Andi Kleen , akpm@osdl.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org, anton@samba.org, paulus@samba.org, linuxppc64-dev@lists.linuxppc.org References: <20040407074239.GG18264@zax> <20040407143447.4d8f08af.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040407143447.4d8f08af.ak@suse.de> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1415 Lines: 31 On Wed, Apr 07, 2004 at 02:34:47PM +0200, Andi Kleen wrote: > On Wed, 7 Apr 2004 17:42:39 +1000 > David Gibson wrote: > > > Currently the kernel does not implement copy-on-write for huge pages - > > in fact any sort of page fault on a hugepage results in a SIGBUS. > > This means that hugepages *always* have MAP_SHARED semantics, even if > > MAP_PRIVATE is requested, and in particular that they are always > > shared across a fork(). Particularly when using hugetlbfs as just a > > source of quasi-anonymous memory, those are rather strange semantics. > > [...] > > Implementing this for ppc64 only is just wrong. Before you do this > I would suggest to factor out the common code in the various hugetlbpage > implementations and then implement it in common code. Yes, I know it needs to be implemented for the other archs, but I wanted to get some feedback on the concept before diving into the other arch details to figure out how to implement it there. -- David Gibson | For every complex problem there is a david AT gibson.dropbear.id.au | solution which is simple, neat and | wrong. http://www.ozlabs.org/people/dgibson - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/