Re: [RFC][PATCH 0/2] Export memblock migrate type to /sysfs

[Badari <pbadari@us.ibm.com>]

KAMEZAWA Hiroyuki wrote:
> On Wed, 24 Oct 2007 09:37:40 -0700
> Badari Pulavarty <pbadari@us.ibm.com> wrote:
>
>   
>> Hi,
>>
>> Now that grouping of pages by mobility is in mainline, I would like 
>> to make use of it for selection memory blocks for hotplug memory remove.
>> Following set of patches exports memblock's migrate type to /sysfs. 
>> This would be useful for user-level agent for selecting memory blocks
>> to try to remove.
>>
>> 	[PATCH 1/2] Fix migratetype_names[] and make it available
>> 	[PATCH 2/2] Add mem_type in /syfs to show memblock migrate type
>>
>>     
> At first, I welcome this patch. Thanks :)
>   
>> Todo:
>>
>> 	Currently, we decide the memblock's migrate type looking at
>> first page of memblock. But on some architectures (x86_64), each
>> memblock can contain multiple groupings of pages by mobility. Is it
>> important to address ?
>>     
>
> Hmm, that is a problem annoying me. There is 2 points.
>
> 1. In such arch, we'll have to use ZONE_MOVABLE for hot-removable.
> 2. But from view of showing information to users, more precice is better
>    of course.
>
> How about showing information as following ?
> ==
> %cat ./memory/memory0/mem_type
>  1 0 0 0 0
> %
> as 
>  Reserved Unmovable Movable Reserve Isolate
>
>   
Personally, I have no problem. But its against the rules of /sysfs - 
"one value per file" rule :(
I would say, lets keep it simple for now and extend it if needed.

Thanks,
Badari

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