Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758892AbXF0SOI (ORCPT ); Wed, 27 Jun 2007 14:14:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752655AbXF0SN6 (ORCPT ); Wed, 27 Jun 2007 14:13:58 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:1288 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752263AbXF0SN5 (ORCPT ); Wed, 27 Jun 2007 14:13:57 -0400 X-AuthUser: davidel@xmailserver.org Date: Wed, 27 Jun 2007 11:13:52 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Hugh Dickins cc: Ulrich Drepper , blaisorblade@yahoo.it, Linux Kernel Mailing List Subject: Re: [patch 2/3] MAP_NOZERO - implement sys_brk2() In-Reply-To: Message-ID: References: X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc 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 Content-Length: 1028 Lines: 26 On Wed, 27 Jun 2007, Hugh Dickins wrote: > In honesty, I should add that I dislike and distrust Davide's > MAP_NOZERO very much indeed! Would much rather leave my cpus > spending a little time in clear_page(). A uid in struct page > (though I'm sure we could find somewhere to tuck it away) - > the horror, the horror! But I've so far failed to find a killer > argument against it, and am hoping for someone else to do so. Little time? Please, do not trust me. Start oprofile and run a kernel build. Look, I'm not even talking about som micro benchmark explicitly built to exploit the thing. A kernel build. You will find clear_page to be the *1st* kernel entry after cc1 and as. That is bad for two reasons. The time it spends in there, and the cache it blows. - Davide - 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/