From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753042AbXGBHFc (ORCPT ); Mon, 2 Jul 2007 03:05:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751123AbXGBHFY (ORCPT ); Mon, 2 Jul 2007 03:05:24 -0400 Received: from mtagate3.de.ibm.com ([195.212.29.152]:8127 "EHLO mtagate3.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751137AbXGBHFV (ORCPT ); Mon, 2 Jul 2007 03:05:21 -0400 Subject: Re: [patch 5/5] Optimize page_mkclean_one From: Martin Schwidefsky Reply-To: schwidefsky@de.ibm.com To: Peter Zijlstra Cc: Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org In-Reply-To: <1183296468.5180.10.camel@lappy> References: <20070629135530.912094590@de.ibm.com> <20070629141528.511942868@de.ibm.com> <1183274153.15924.6.camel@localhost> <1183296468.5180.10.camel@lappy> Content-Type: text/plain Organization: IBM Corporation Date: Mon, 02 Jul 2007 09:07:26 +0200 Message-Id: <1183360046.12198.8.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.10.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2007-07-01 at 15:27 +0200, Peter Zijlstra wrote: > > But I could easily be overlooking something: Peter will recall. > > /me tries to get his brain up to speed after the OLS closing party :-) Oh-oh, the Black Thorn party :-) > I did both pte_dirty and pte_write because I was extra careful. One > _should_ imply the other, but since we'll be clearing both, I thought it > prudent to also check both. Just ran a little experiment: I've added a simple WARN_ON(ret == 0) to page_mkclean after the page_test_dirty() check to see if there are cases where the page is dirty and all ptes are read-only. A little stress run including massive swap did not print a single warning. > I will have to think on this a little more, but I'm currently of the > opinion that the optimisation is not correct. But I'll have a thorough > look at s390 again when I get home. I think the patch is correct, although I beginning to doubt that is has any effect. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.