Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753248Ab0HWNmD (ORCPT ); Mon, 23 Aug 2010 09:42:03 -0400 Received: from smtp101.prem.mail.ac4.yahoo.com ([76.13.13.40]:35751 "HELO smtp101.prem.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751547Ab0HWNmC (ORCPT ); Mon, 23 Aug 2010 09:42:02 -0400 X-Yahoo-SMTP: _Dag8S.swBC1p4FJKLCXbs8NQzyse1SYSgnAbY0- X-YMail-OSG: rxLyUFsVM1lVR1k_5BzqetnX06xeil2sAXJvp4fI9djsOco 63hABYEp4JZD4C9AIKMDfCD0GDH_hXftYtQ_8Q0cLTqqDyaIcnM9DUwzj0a3 MTuScDze.eEpwU6phZSLLIH.zpQfcu9zF76jY3.0j5vH_P1Im4Cpxw._noRJ EN_il3vg8XsK0BSswWBBFmFokd_Te5V3qevijB0C5CcAkRQvOeg0_PHo_BO. t X-Yahoo-Newman-Property: ymail-3 Date: Mon, 23 Aug 2010 08:41:56 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@router.home To: Mel Gorman cc: Andrew Morton , Linux Kernel List , linux-mm@kvack.org, Rik van Riel , Johannes Weiner , Minchan Kim , KAMEZAWA Hiroyuki , KOSAKI Motohiro Subject: Re: [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake In-Reply-To: <20100823130315.GQ19797@csn.ul.ie> Message-ID: References: <1282550442-15193-1-git-send-email-mel@csn.ul.ie> <1282550442-15193-3-git-send-email-mel@csn.ul.ie> <20100823130315.GQ19797@csn.ul.ie> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 967 Lines: 21 On Mon, 23 Aug 2010, Mel Gorman wrote: > > The delta of the counters could also be reduced to increase accuracy. > > See refresh_zone_stat_thresholds(). > True, but I thought that would introduce a constant performance penalty > for a corner case which I didn't like. Sure, an increased frequency of updates would increase the chance of bouncing cachelines. But the bouncing cacheline scenario for the vm counters was tuned for applications that continually allocate pages in parallel. When the vm gets into a state where continual reclaim is necessary then the counters are not that frequently updated. If the machine is already slowing down due to reclaim then the vm can likely affort more frequent counter updates. -- 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/