Message-ID: <55821D85.3070208@huawei.com>
Date: Thu, 18 Jun 2015 09:23:17 +0800
From: Xishi Qiu <qiuxishi@huawei.com>
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To: Vlastimil Babka <vbabka@suse.cz>
CC: Andrew Morton <akpm@linux-foundation.org>, <nao.horiguchi@gmail.com>,
        Yinghai Lu <yinghai@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        "Thomas Gleixner" <tglx@linutronix.de>, <mingo@elte.hu>,
        Xiexiuqi <xiexiuqi@huawei.com>, Hanjun Guo <guohanjun@huawei.com>,
        "Luck, Tony" <tony.luck@intel.com>, Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 00/12] mm: mirrored memory support for page buddy
 allocations
References: <55704A7E.5030507@huawei.com> <557FD5F8.10903@suse.cz> <557FDB9B.1090105@huawei.com> <557FF06A.3020000@suse.cz>
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On 2015/6/16 17:46, Vlastimil Babka wrote:

> On 06/16/2015 10:17 AM, Xishi Qiu wrote:
>> On 2015/6/16 15:53, Vlastimil Babka wrote:
>>
>>> On 06/04/2015 02:54 PM, Xishi Qiu wrote:
>>>>
>>>> I think add a new migratetype is btter and easier than a new zone, so I use
>>>
>>> If the mirrored memory is in a single reasonably compact (no large holes) range
>>> (per NUMA node) and won't dynamically change its size, then zone might be a
>>> better option. For one thing, it will still allow distinguishing movable and
>>> unmovable allocations within the mirrored memory.
>>>
>>> We had enough fun with MIGRATE_CMA and all kinds of checks it added to allocator
>>> hot paths, and even CMA is now considering moving to a separate zone.
>>>
>>
>> Hi, how about the problem of this case:
>> e.g. node 0: 0-4G(dma and dma32)
>>      node 1: 4G-8G(normal), 8-12G(mirror), 12-16G(normal),
>> so more than one normal zone in a node? or normal zone just span the mirror zone?
> 
> Normal zone can span the mirror zone just fine. However, it will result in zone
> scanners such as compaction to skip over the mirror zone inefficiently. Hmm...
> 

Hi Vlastimil,

If there are many mirror regions in one node, then it will be many holes in the
normal zone, is this fine?

Thanks,
Xishi Qiu

> 
> .
> 


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