From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate8.de.ibm.com (8.13.8/8.13.8) with ESMTP id l6275JZq252072 for ; Mon, 2 Jul 2007 07:05:19 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l6275JRu1601560 for ; Mon, 2 Jul 2007 09:05:19 +0200 Received: from d12av02.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l6275IDY015824 for ; Mon, 2 Jul 2007 09:05:19 +0200 Subject: Re: [patch 5/5] Optimize page_mkclean_one From: Martin Schwidefsky Reply-To: schwidefsky@de.ibm.com 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 Date: Mon, 02 Jul 2007 09:07:26 +0200 Message-Id: <1183360046.12198.8.camel@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Hugh Dickins , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org