Re: [PATCH] mm: fix set pageblock migratetype when boot

[Xishi Qiu]

On 2015/6/26 19:04, Mel Gorman wrote:

> On Fri, Jun 26, 2015 at 06:09:05PM +0800, Xishi Qiu wrote:
>> memmap_init_zone()
>> 	...
>> 	if ((z->zone_start_pfn <= pfn)
>> 	    && (pfn < zone_end_pfn(z))
>> 	    && !(pfn & (pageblock_nr_pages - 1)))
>> 		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
>> 	...
>>
>> If the pfn does not align to pageblock, it will not init the migratetype.
> 
> What important impact does that have? It should leave a partial pageblock
> as MIGRATE_UNMOVABLE which is fine by me.
> 

Hi Mel,

The impact is less, it's OK to ignore it.

Thanks,
Xishi Qiu

>> So call it for every page, it will takes more time, but it doesn't matter, 
>> this function will be called only in boot or hotadd memory.
>>
> 
> It's a lot of additional overhead to add to memory initialisation. It
> would need to be for an excellent reason with no alternative solution.
> 



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