From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964920AbWFZEUb (ORCPT ); Mon, 26 Jun 2006 00:20:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965020AbWFZEUb (ORCPT ); Mon, 26 Jun 2006 00:20:31 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:46288 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S964920AbWFZEUa (ORCPT ); Mon, 26 Jun 2006 00:20:30 -0400 Date: Sun, 25 Jun 2006 21:20:17 -0700 (PDT) From: Christoph Lameter To: Arjan van de Ven cc: Andrew Morton , Ravikiran G Thirumalai , linux-kernel@vger.kernel.org Subject: Re: remove __read_mostly? In-Reply-To: <1151271890.4940.58.camel@laptopd505.fenrus.org> Message-ID: References: <20060625115736.d90e1241.akpm@osdl.org> <1151271890.4940.58.camel@laptopd505.fenrus.org> 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 Sun, 25 Jun 2006, Arjan van de Ven wrote: > On Sun, 2006-06-25 at 11:57 -0700, Andrew Morton wrote: > > I'm thinking we should remove __read_mostly. > > > > Because if we use this everywhere where it's supposed to be used, we end up > > with .bss and .data 100% populated with write-often variables, packed > > closely together. The cachelines will really flying around. > > > one thing we could/should do is have a "written during boot only" > section; which we then can mark read only as well :) To replicate an IRIX idea: We could have section with variables that can only be modified by special command. F.e. enable_write_to_most_read_section() disable_write_to_most_read_section() This section could be a per cpu section that would be replicated to all nodes on the system on disable_write_to_most_read_section(). That would mean that critical read only data would be node local.