Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755742Ab0FYPVY (ORCPT ); Fri, 25 Jun 2010 11:21:24 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:42000 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751621Ab0FYPVX (ORCPT ); Fri, 25 Jun 2010 11:21:23 -0400 Message-ID: <4C24C96F.4030709@austin.ibm.com> Date: Fri, 25 Jun 2010 10:21:19 -0500 From: Nathan Fontenot User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100423 Thunderbird/3.0.4 MIME-Version: 1.0 To: Andi Kleen CC: KOSAKI Motohiro , linux-kernel@vger.kernel.org Subject: Re: [PATCH] memory hotplug disable boot option References: <4C24012B.9030506@austin.ibm.com> <20100625105340.803C.A69D9226@jp.fujitsu.com> <87d3vfeage.fsf@basil.nowhere.org> <4C24C279.3050206@austin.ibm.com> <20100625145622.GB13421@basil.fritz.box> In-Reply-To: <20100625145622.GB13421@basil.fritz.box> 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 Content-Length: 1385 Lines: 30 On 06/25/2010 09:56 AM, Andi Kleen wrote: > On Fri, Jun 25, 2010 at 09:51:37AM -0500, Nathan Fontenot wrote: >>> >>>>> Proposed patch to disable memory hotplug via a boot option, >>>>> mem_hotplug=[on|off]. The patch only disables memory hotplug in that it >>>>> prevents the creation of the memory sysfs directories for memory sections. >>>>> >>>>> This patch is meant to help alleviate very long boot times on systems with >>>>> large memory (1+ TB) and many memory sections (10's of thousands). >>>> >>>> Why making simple /sys file is so slowly? Couldn't we fix such performance >>>> problem? >> >> The issue is the large number of sysfs memory directories that get created. >> On a system with 1 TB of memory I am seeing ~63,00 directories. The long > > Maybe you could simply make the memory blocks larger on such large systems? > I agree 6k blocks are probably not very useful, but maybe 10 or 100 are? > Yes, this would work to reduce the number of memory sections created. The reason I have not gone this route is that increasing the memory section size would break DLPAR memory add and remove for powerpc pseries. -Nathan -- 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/