From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755387AbXLXBNv (ORCPT ); Sun, 23 Dec 2007 20:13:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751403AbXLXBNm (ORCPT ); Sun, 23 Dec 2007 20:13:42 -0500 Received: from mx1.redhat.com ([66.187.233.31]:50062 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751010AbXLXBNl (ORCPT ); Sun, 23 Dec 2007 20:13:41 -0500 Date: Sun, 23 Dec 2007 20:11:49 -0500 From: Rik van Riel To: balbir@linux.vnet.ibm.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, lee.schermerhorn@hp.com Subject: Re: [patch 00/20] VM pageout scalability improvements Message-ID: <20071223201149.7b88888f@bree.surriel.com> In-Reply-To: <476EE858.202@linux.vnet.ibm.com> References: <20071218211539.250334036@redhat.com> <476D7334.4010301@linux.vnet.ibm.com> <20071222192119.030f32d5@bree.surriel.com> <476EE858.202@linux.vnet.ibm.com> Organization: Red Hat, Inc. X-Mailer: Claws Mail 3.0.2 (GTK+ 2.10.4; x86_64-redhat-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 On Mon, 24 Dec 2007 04:29:36 +0530 Balbir Singh wrote: > Rik van Riel wrote: > > In the real world, users with large JVMs on their servers, which > > sometimes go a little into swap, can trigger this system. All of > > the CPUs end up scanning the active list, and all pages have the > > referenced bit set. Even if the system eventually recovers, it > > might as well have been dead. > > > > Going into swap a little should only take a little bit of time. > > Very fascinating, so we need to scale better with larger memory. > I suspect part of the answer will lie with using large/huge pages. Linus vetoed going to a larger soft page size, with good reason. Just look at how much the 64kB page size on PPC64 sucks for most workloads - it works for PPC64 because people buy PPC64 monster systems for the kinds of monster workloads that work well with a large page size, but it definately isn't general purpose.