From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753432Ab0IBRjv (ORCPT ); Thu, 2 Sep 2010 13:39:51 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:33537 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752887Ab0IBRju (ORCPT ); Thu, 2 Sep 2010 13:39:50 -0400 Message-ID: <4C7FE163.4000906@austin.ibm.com> Date: Thu, 02 Sep 2010 12:39:47 -0500 From: Nathan Fontenot User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.11) Gecko/20100713 Thunderbird/3.0.6 MIME-Version: 1.0 To: Anton Blanchard CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@ozlabs.org, KAMEZAWA Hiroyuki , Dave Hansen , Greg KH , akpm@linux-foundation.org Subject: Re: [PATCH 0/8] v5 De-couple sysfs memory directories from memory sections References: <4C60407C.2080608@austin.ibm.com> <20100831215745.GA7641@kryten> In-Reply-To: <20100831215745.GA7641@kryten> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/31/2010 04:57 PM, Anton Blanchard wrote: > > Hi Nathan, > >> This set of patches de-couples the idea that there is a single >> directory in sysfs for each memory section. The intent of the >> patches is to reduce the number of sysfs directories created to >> resolve a boot-time performance issue. On very large systems >> boot time are getting very long (as seen on powerpc hardware) >> due to the enormous number of sysfs directories being created. >> On a system with 1 TB of memory we create ~63,000 directories. >> For even larger systems boot times are being measured in hours. >> >> This set of patches allows for each directory created in sysfs >> to cover more than one memory section. The default behavior for >> sysfs directory creation is the same, in that each directory >> represents a single memory section. A new file 'end_phys_index' >> in each directory contains the physical_id of the last memory >> section covered by the directory so that users can easily >> determine the memory section range of a directory. > > I tested this on a POWER7 with 2TB memory and the boot time improved from > greater than 6 hours (I gave up), to under 5 minutes. Nice! Thanks for testing this out. I was able to test this on a 1 TB system and saw memory sysfs creation times go from 10 minutes to a few seconds. It's good to see the difference for a 2 TB system. -Nathan