From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751187AbWBESmE (ORCPT ); Sun, 5 Feb 2006 13:42:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751199AbWBESmE (ORCPT ); Sun, 5 Feb 2006 13:42:04 -0500 Received: from xproxy.gmail.com ([66.249.82.193]:41134 "EHLO xproxy.gmail.com") by vger.kernel.org with ESMTP id S1751187AbWBESmD convert rfc822-to-8bit (ORCPT ); Sun, 5 Feb 2006 13:42:03 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=RS/IpvlCnJ4Y8sbeet3AzUNdyfktqb551KXNphK0jvKXako/QtTLwXfXV9HbfOYUK+Z6DX7icSLhagm/yxI3pHUDYwXX6NqvvEqxVIzQykfm/RFWDXwnRWVcCvihwGwFgxyNwgpgeQwJU718GXy7nw8hhFzQQ2WEzynd1GZj9x8= Message-ID: <986ed62e0602051042t11f3d81scafec9277af892e4@mail.gmail.com> Date: Sun, 5 Feb 2006 10:42:00 -0800 From: "Barry K. Nathan" To: Mark Lord Subject: Re: [PATCH ] VMSPLIT config options (with default config fixed) Cc: Greg Norris , linux-kernel@vger.kernel.org In-Reply-To: <43C53CA2.7070002@rtr.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <20060110132957.GA28666@elte.hu> <20060110143931.GM3389@suse.de> <43C3E9C2.1000309@rtr.ca> <20060110173217.GU3389@suse.de> <43C3F0CA.10205@rtr.ca> <43C403BA.1050106@pobox.com> <43C40803.2000106@rtr.ca> <20060111160050.GA5472@yggdrasil.localdomain> <43C53CA2.7070002@rtr.ca> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 1/11/06, Mark Lord wrote: > Greg Norris wrote: > > Is there any benefit/point to enabling HIGHMEM when using this patch, > > assuming that physical memory is smaller than the address space? For > > example, when using VMSPLIT_3G_OPT on a box with 1G of memory. > > No. In fact, there should be a (very) tiny performance gain > by NOT enabling HIGHMEM -- things like kmap() should get simpler. Actually, IIRC if you have an x86 CPU (or x86-64 running a 32-bit kernel) which has a no-execute bit, to support that (i.e. to have a more secure system) you need to use HIGHMEM64G, no matter how much or how little RAM you have. -- -Barry K. Nathan