From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752847AbYIXN4s (ORCPT ); Wed, 24 Sep 2008 09:56:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752069AbYIXN4k (ORCPT ); Wed, 24 Sep 2008 09:56:40 -0400 Received: from perninha.conectiva.com.br ([200.140.247.100]:46985 "EHLO perninha.conectiva.com.br" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752065AbYIXN4j (ORCPT ); Wed, 24 Sep 2008 09:56:39 -0400 Date: Wed, 24 Sep 2008 10:56:57 -0300 From: "Luiz Fernando N. Capitulino" To: hamid.jahanjou@gmail.com Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] VM: Implements the swap-out page-clustering technique Message-ID: <20080924105657.78265a63@doriath.conectiva> In-Reply-To: <48BFCECE.90103@gmail.com> References: <48BFCECE.90103@gmail.com> Organization: Mandriva X-Mailer: Claws Mail 3.5.0 (GTK+ 2.14.2; i586-mandriva-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, 04 Sep 2008 15:34:30 +0330 "Hamid R. Jahanjou" escreveu: | From: Hamid R. Jahanjou | | Implements the idea of swap-out page clustering from *BSD for | Linux. Each time a candidate page is to be swapped out, | virtually-nearby pages are scanned to find eligible pages to be | swapped out too as a cluster. This technique increases the likelihood of | bringing in related data on a page fault and decreases swap space | fragmentation in the long run. Currently, Linux searches only | physically-nearby pages which is not optimal since, over time, physically- | adjacent pages may become unrelated. | | The code can be statically tuned. No benchmarks. I'm not sure whether | the added complexity is acceptable. Sorry for this (very) late response, but I ran some very simple tests this week and thought you might be interested in the results. The test machine has 512MB of RAM. For the tests I booted with 64MB and setup a 512MB swap file. For the first test I let an allyesconfig kernel building for several hours with six jobs (make -j6). I did not have any problems, so considering that your code was used I think it is stable enough. In the second test I have built an allnoconfig kernel with and without your patches, still with six jobs. Results: 2.6.27-rc7-vanilla 44:12 minutes 2.6.27-rc7-pgc 52:09 minutes (pgc means page-clustering patches). For both builds I did not change any swap paramenter and I could observe that about 80MB of swap were used most of the time. But please, note that these tests were quite far from being 'scientific' eg. I should have built the kernel more times and should have tried other setups... I will wait for the next version of the patches to run more serious tests. -- Luiz Fernando N. Capitulino