From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e4.ny.us.ibm.com (e4.ny.us.ibm.com [32.97.182.144]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e4.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 09251B7176 for ; Fri, 3 Sep 2010 03:39:52 +1000 (EST) Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e4.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id o82HOlNY025329 for ; Thu, 2 Sep 2010 13:24:47 -0400 Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o82Hdn7X080940 for ; Thu, 2 Sep 2010 13:39:49 -0400 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o82HdmQG026134 for ; Thu, 2 Sep 2010 11:39:48 -0600 Message-ID: <4C7FE163.4000906@austin.ibm.com> Date: Thu, 02 Sep 2010 12:39:47 -0500 From: Nathan Fontenot MIME-Version: 1.0 To: Anton Blanchard 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 Cc: linuxppc-dev@ozlabs.org, Greg KH , linux-kernel@vger.kernel.org, Dave Hansen , linux-mm@kvack.org, akpm@linux-foundation.org, KAMEZAWA Hiroyuki List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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