From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760342AbXJLRnt (ORCPT ); Fri, 12 Oct 2007 13:43:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755592AbXJLRnj (ORCPT ); Fri, 12 Oct 2007 13:43:39 -0400 Received: from pasmtpb.tele.dk ([80.160.77.98]:36168 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753759AbXJLRni (ORCPT ); Fri, 12 Oct 2007 13:43:38 -0400 Date: Fri, 12 Oct 2007 19:45:07 +0200 From: Sam Ravnborg To: "Maciej W. Rozycki" Cc: Franck Bui-Huu , Ralf Baechle , linux-arch@vger.kernel.org, linux-mips@linux-mips.org, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Discardable strings for init and exit sections Message-ID: <20071012174507.GA21193@uranus.ravnborg.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 12, 2007 at 05:50:01PM +0100, Maciej W. Rozycki wrote: > We currently have infrastructure for discardable text and data, but no > such thing for strings. This is especially notable for inline strings > such as ones used by printk() which are left behind resident in the memory > throughout the life of the system even though code referring to them has > been removed. What is the actual benefit here expressed in real numbers? For the __init/__exit notation that is yet only partially correct we often see corner cases where one ask if it is really worth it. Adding the discard functionality for strings seems like a logical extension but there is a benefit/pain ratio to consider. So real numbers please. A few general notes to the patch. 1) We want to consolidate this in include/asm-generic/vmlinux* somehow and this should be doen as a separate step. 2) If we introduce discardable strings then we shall in parallel add build time checks so we catch strings marked as discardable which is used outside a discardable compatible function. Sam