From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx137.postini.com [74.125.245.137]) by kanga.kvack.org (Postfix) with SMTP id 6FCE36B0069 for ; Wed, 16 Jan 2013 18:01:00 -0500 (EST) Message-ID: <50F73111.40009@zytor.com> Date: Wed, 16 Jan 2013 15:00:33 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH v5 0/5] Add movablecore_map boot option References: <1358154925-21537-1-git-send-email-tangchen@cn.fujitsu.com> <50F440F5.3030006@zytor.com> <20130114143456.3962f3bd.akpm@linux-foundation.org> <3908561D78D1C84285E8C5FCA982C28F1C97C2DA@ORSMSX108.amr.corp.intel.com> <20130114144601.1c40dc7e.akpm@linux-foundation.org> <50F647E8.509@jp.fujitsu.com> <20130116132953.6159b673.akpm@linux-foundation.org> <50F72333.60200@jp.fujitsu.com> In-Reply-To: <50F72333.60200@jp.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: akpm@linux-foundation.org, isimatu.yasuaki@jp.fujitsu.com, tony.luck@intel.com, tangchen@cn.fujitsu.com, jiang.liu@huawei.com, wujianguo@huawei.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com, linfeng@cn.fujitsu.com, yinghai@kernel.org, rob@landley.net, minchan.kim@gmail.com, mgorman@suse.de, rientjes@google.com, guz.fnst@cn.fujitsu.com, rusty@rustcorp.com.au, lliubbo@gmail.com, jaegeuk.hanse@gmail.com, glommer@parallels.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On 01/16/2013 02:01 PM, KOSAKI Motohiro wrote: >>>> >>>> Things I'm wondering: >>>> >>>> - is there *really* a case for retaining the boot option if/when >>>> SRAT support is available? >>> >>> Yes. If SRAT support is available, all memory which enabled hotpluggable >>> bit are managed by ZONEMOVABLE. But performance degradation may >>> occur by NUMA because we can only allocate anonymous page and page-cache >>> from these memory. >>> >>> In this case, if user cannot change SRAT information, user needs a way to >>> select/set removable memory manually. >> >> If I understand this correctly you mean that once SRAT parsing is >> implemented, the user can use movablecore_map to override that SRAT >> parsing, yes? That movablecore_map will take precedence over SRAT? > > I think movablecore_map (I prefer movablemem than it, btw) should behave so. > because of, for past three years, almost all memory hotplug bug was handled > only I and kamezawa-san and, afaik, both don't have hotremove aware specific > hardware. > > So, if the new feature require specific hardware, we can't maintain this area > any more. > It is more so than that: the design principle should always be that lower-level directives, if present, take precedence over higher-level directives. The reason for that should be pretty obvious: one of the main uses of the low-level directives is to override the high-level directives due to bugs or debugging needs. -hpa -- 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