Re: [PATCH v6 2/6] mm/cma: introduce new zone, ZONE_CMA

[Chen Feng]

On 2016/11/7 15:44, Chen Feng wrote:
> 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@xxxxxxxxxxxxxxx/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].
> 
> 
My test case is run 60 applications and alloc 512MB ION memory.

Repeat this action 50 times

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