Re: [PATCH] mm: get rid of unnecessary pageblock scanning in setup_zone_migrate_reserve

[KOSAKI Motohiro]

> > Nit. I would like to add following hunk. This is just nit because moving
> > reserve pageblock is extreme rare.
> >
> > 		if (block_migratetype == MIGRATE_RESERVE) {
> > +                       found++;
> > 			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
> > 			move_freepages_block(zone, page, MIGRATE_MOVABLE);
> > 		}
>
> I don't really see the advantage but if you think it is necessary then I
> do not object either.

For example, a zone has five pageblock b1,b2,b3,b4,b5 and b1 has MIGRATE_RESERVE.
When hotremove b1 and hotadd again, your code need to scan all of blocks. But
mine only need to scan b1 and b2. I mean that's a hotplug specific optimization.


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