From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 0B23B6B006C for ; Mon, 29 Jun 2015 22:54:27 -0400 (EDT) Received: by pacws9 with SMTP id ws9so1077442pac.0 for ; Mon, 29 Jun 2015 19:54:26 -0700 (PDT) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com. [58.251.152.64]) by mx.google.com with ESMTPS id nx9si33950250pbb.73.2015.06.29.19.54.22 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 29 Jun 2015 19:54:26 -0700 (PDT) Message-ID: <559202E2.8060609@huawei.com> Date: Tue, 30 Jun 2015 10:45:54 +0800 From: Xishi Qiu MIME-Version: 1.0 Subject: Re: [RFC v2 PATCH 2/8] mm: introduce MIGRATE_MIRROR to manage the mirrored pages References: <558E084A.60900@huawei.com> <558E0948.2010104@huawei.com> <5590F4A7.4030606@jp.fujitsu.com> In-Reply-To: <5590F4A7.4030606@jp.fujitsu.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Kamezawa Hiroyuki Cc: Andrew Morton , "H. Peter Anvin" , Ingo Molnar , "Luck, Tony" , Hanjun Guo , Xiexiuqi , leon@leon.nu, Dave Hansen , Naoya Horiguchi , Vlastimil Babka , Mel Gorman , Linux MM , LKML On 2015/6/29 15:32, Kamezawa Hiroyuki wrote: > On 2015/06/27 11:24, Xishi Qiu wrote: >> This patch introduces a new migratetype called "MIGRATE_MIRROR", it is used to >> allocate mirrored pages. >> When cat /proc/pagetypeinfo, you can see the count of free mirrored blocks. >> >> Signed-off-by: Xishi Qiu > > My fear about this approarch is that this may break something existing. > > Now, when we add MIGRATE_MIRROR type, we'll hide attributes of pageblocks as > MIGRATE_UNMOVABOLE, MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE. > > Logically, MIRROR attribute is independent from page mobility and this overwrites > will make some information lost. > > Then, > >> --- >> include/linux/mmzone.h | 9 +++++++++ >> mm/page_alloc.c | 3 +++ >> mm/vmstat.c | 3 +++ >> 3 files changed, 15 insertions(+) >> >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index 54d74f6..54e891a 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -39,6 +39,9 @@ enum { >> MIGRATE_UNMOVABLE, >> MIGRATE_RECLAIMABLE, >> MIGRATE_MOVABLE, >> +#ifdef CONFIG_MEMORY_MIRROR >> + MIGRATE_MIRROR, >> +#endif > > I think > MIGRATE_MIRROR_UNMOVABLE, > MIGRATE_MIRROR_RECLAIMABLE, > MIGRATE_MIRROR_MOVABLE, <== adding this may need discuss. > MIGRATE_MIRROR_RESERVED, <== reserved pages should be maintained per mirrored/unmirrored. > Hi Kame, You mean add 3 or 4 new migratetype? > should be added with the following fallback list. > > /* > * MIRROR page range is defined by firmware at boot. The range is limited > * and is used only for kernel memory mirroring. > */ > [MIGRATE_UNMOVABLE_MIRROR] = {MIGRATE_RECLAIMABLE_MIRROR, MIGRATE_RESERVE} > [MIGRATE_RECLAIMABLE_MIRROR] = {MIGRATE_UNMOVABLE_MIRROR, MIGRATE_RESERVE} > Why not like this: {MIGRATE_RECLAIMABLE_MIRROR, MIGRATE_MIRROR_RESERVED, MIGRATE_RESERVE} > Then, we'll not lose the original information of "Reclaiable Pages". > > One problem here is whteher we should have MIGRATE_RESERVE_MIRROR. > > If we never allow users to allocate mirrored memory, we should have MIGRATE_RESERVE_MIRROR. > But it seems to require much more code change to do that. > > Creating a zone or adding an attribues to zones are another design choice. > If we add a new zone, mirror_zone will span others, I'm worry about this maybe have problems. Thanks, Xishi Qiu > Anyway, your patch doesn't takes care of reserved memory calculation at this point. > Please check setup_zone_migrate_reserve() That will be a problem. > > Thanks, > -Kame > -- 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