From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx148.postini.com [74.125.245.148]) by kanga.kvack.org (Postfix) with SMTP id 9D5456B0072 for ; Thu, 29 Nov 2012 06:05:41 -0500 (EST) Date: Thu, 29 Nov 2012 11:05:35 +0000 From: Mel Gorman Subject: Re: [PATCH v2 0/5] Add movablecore_map boot option Message-ID: <20121129110535.GY8218@suse.de> References: <1353667445-7593-1-git-send-email-tangchen@cn.fujitsu.com> <50B5CFAE.80103@huawei.com> <3908561D78D1C84285E8C5FCA982C28F1C95EDCE@ORSMSX108.amr.corp.intel.com> <50B73B22.90500@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <50B73B22.90500@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: "Luck, Tony" , Jiang Liu , Tang Chen , "hpa@zytor.com" , "akpm@linux-foundation.org" , "rob@landley.net" , "laijs@cn.fujitsu.com" , "wency@cn.fujitsu.com" , "linfeng@cn.fujitsu.com" , "yinghai@kernel.org" , "kosaki.motohiro@jp.fujitsu.com" , "minchan.kim@gmail.com" , "rientjes@google.com" , "rusty@rustcorp.com.au" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-doc@vger.kernel.org" , Len Brown , "Wang, Frank" On Thu, Nov 29, 2012 at 07:38:26PM +0900, Yasuaki Ishimatsu wrote: > Hi Tony, > > 2012/11/29 6:34, Luck, Tony wrote: > >>1. use firmware information > >> According to ACPI spec 5.0, SRAT table has memory affinity structure > >> and the structure has Hot Pluggable Filed. See "5.2.16.2 Memory > >> Affinity Structure". If we use the information, we might be able to > >> specify movable memory by firmware. For example, if Hot Pluggable > >> Filed is enabled, Linux sets the memory as movable memory. > >> > >>2. use boot option > >> This is our proposal. New boot option can specify memory range to use > >> as movable memory. > > > >Isn't this just moving the work to the user? To pick good values for the > > Yes. > > >movable areas, they need to know how the memory lines up across > >node boundaries ... because they need to make sure to allow some > >non-movable memory allocations on each node so that the kernel can > >take advantage of node locality. > > There is no problem. > Linux has already two boot options, kernelcore= and movablecore=. > So if we use them, non-movable memory is divided into each node evenly. > The motivation for those options was to reserve a percentage of memory to be used for hugepage allocation. If hugepages were not being used at a particular time then they could be used for other purposes. While the system could in theory face lowmem/highmem style problems, in practice it did not happen because the memory would be allocated as hugetlbfs pages and unavailable anyway. The same does not really apply to a general purpose system that you want to support memory hot-remove on so be wary of lowmem/highmem style problems caused by relying too heavily on ZONE_MOVABLE. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org