From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754511Ab3EMIkN (ORCPT ); Mon, 13 May 2013 04:40:13 -0400 Received: from cantor2.suse.de ([195.135.220.15]:54667 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754467Ab3EMIkM (ORCPT ); Mon, 13 May 2013 04:40:12 -0400 Date: Mon, 13 May 2013 09:40:08 +0100 From: Mel Gorman To: PINTU KUMAR Cc: "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [Query] Performance degradation with memory compaction (on QC chip-set) Message-ID: <20130513084008.GO11497@suse.de> References: <1310394396.24243.YahooMailNeo@web162006.mail.bf1.yahoo.com> <20110711145448.GI15285@suse.de> <1310462107.89450.YahooMailNeo@web162007.mail.bf1.yahoo.com> <20110712093510.GB7529@suse.de> <1310484381.60694.YahooMailNeo@web162011.mail.bf1.yahoo.com> <20110712154404.GD7529@suse.de> <1368414026.58026.YahooMailNeo@web160103.mail.bf1.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1368414026.58026.YahooMailNeo@web160103.mail.bf1.yahoo.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 12, 2013 at 08:00:26PM -0700, PINTU KUMAR wrote: > Dear Mel Gorman, > > I have one question about memory compaction. > Kernel version: kernel-3.4 (ARM) > Chipset: Qual-Comm MSM8930 dual-core. > > We wanted to enable CONFIG_COMPACTION for our product with kernel-3.4. > But QC commented that, enabling compaction on their chip-set is causing performance degradation for some streaming scenarios (from the beginning). > > I wanted to know is this possible always? > We used compaction with exynos processor and did not observe any performance degradation. > I suspect one of their drivers are using high-order allocations and hitting compaction as a result. Compaction is not guaranteed to cause overhead but if it's in use then the scanning and copying overhead can cause problems. > Please let me know your comments. > It will be helpful to decide on enabling compaction or not. > Depends on workload and drivers. -- Mel Gorman SUSE Labs