From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262154AbUKQCMJ (ORCPT ); Tue, 16 Nov 2004 21:12:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262158AbUKQCLP (ORCPT ); Tue, 16 Nov 2004 21:11:15 -0500 Received: from fw.osdl.org ([65.172.181.6]:44260 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262159AbUKQBuu (ORCPT ); Tue, 16 Nov 2004 20:50:50 -0500 Date: Tue, 16 Nov 2004 17:50:36 -0800 (PST) From: Linus Torvalds To: David Howells cc: akpm@osdl.org, hch@infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] Making compound pages mandatory In-Reply-To: <2315.1100630906@redhat.com> Message-ID: References: <2315.1100630906@redhat.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 Tue, 16 Nov 2004, David Howells wrote: > > Do you have any objection to compound pages being made mandatory, even without > HUGETLB support? I haven't really looked into it, so I cannot make an informed decision. How big is the overhead? And what's the _point_, since we don't seem to need them normally, but the code is there for people who _do_ need them? I don't generally like two paths, but quite frankly, I consider the non-compound case the regular case right now. How expensive does the compound pages end up being? Is it just one more pointer chase on every get_page/put_page, or what? Does anybody have numbers for before/after that are otherwise comparable? Linus