linux-kernel - Re: [PATCH v6 2/6] mm/cma: introduce new zone, ZONE

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Message-ID: <582030CB.80905@hisilicon.com>
Date:   Mon, 7 Nov 2016 15:44:11 +0800
From:   Chen Feng <puck.chen@...ilicon.com>
To:     Joonsoo Kim <iamjoonsoo.kim@....com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Rik van Riel <riel@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        <mgorman@...hsingularity.net>,
        "Laura Abbott" <lauraa@...eaurora.org>,
        Minchan Kim <minchan@...nel.org>,
        "Marek Szyprowski" <m.szyprowski@...sung.com>,
        Michal Nazarewicz <mina86@...a86.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Vlastimil Babka <vbabka@...e.cz>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <saberlily.xia@...ilicon.com>,
        Zhuangluan Su <suzhuangluan@...ilicon.com>,
        Dan Zhao <dan.zhao@...ilicon.com>
Subject: Re: [PATCH v6 2/6] mm/cma: introduce new zone, ZONE_CMA

On 2016/11/7 15:27, Joonsoo Kim wrote:
> On Mon, Nov 07, 2016 at 03:08:49PM +0800, Chen Feng wrote:
>>
>>
>> On 2016/11/7 14:15, Joonsoo Kim wrote:
>>> On Tue, Nov 01, 2016 at 03:58:32PM +0800, Chen Feng wrote:
>>>> Hello, I hava a question on cma zone.
>>>>
>>>> When we have cma zone, cma zone will be the highest zone of system.
>>>>
>>>> In android system, the most memory allocator is ION. Media system will
>>>> alloc unmovable memory from it.
>>>>
>>>> On low memory scene, will the CMA zone always do balance?
>>>
>>> Allocation request for low zone (normal zone) would not cause CMA zone
>>> to be balanced since it isn't helpful.
>>>
>> Yes. But the cma zone will run out soon. And it always need to do balance.
>>
>> How about use migrate cma before movable and let cma type to fallback movable.
>>
>> https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1263745.html
> 
> ZONE_CMA approach will act like as your solution. Could you elaborate
> more on the problem of zone approach?
> 

The ZONE approach is that makes cma pages in a zone. It can cause a higher swapin/out
than use migrate cma first.

The higher swapin/out may have a performance effect to application. The application may
use too much time swapin memory.

You can see my tested result attached for detail. And the baseline is result of [1].


[1] https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1263745.html
> Thanks.
> 
> .
> 

Download attachment "CMA-ZONE with fallback.PNG" of type "image/png" (36910 bytes)