linux-kernel - Re: [RFC PATCH 2/3 V1] mm, page migrate: add MIGRATE

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Date:	Wed, 04 Jul 2012 18:50:26 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Mel Gorman <mel@....ul.ie>
CC:	Chris Metcalf <cmetcalf@...era.com>, Len Brown <lenb@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andi Kleen <andi@...stfloor.org>, Julia Lawall <julia@...u.dk>,
	David Howells <dhowells@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Kay Sievers <kay.sievers@...y.org>,
	Ingo Molnar <mingo@...e.hu>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Daniel Kiper <dkiper@...-space.pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Michal Hocko <mhocko@...e.cz>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Minchan Kim <minchan@...nel.org>,
	Michal Nazarewicz <mina86@...a86.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Rik van Riel <riel@...hat.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Christoph Lameter <cl@...ux.com>,
	David Rientjes <rientjes@...gle.com>,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [RFC PATCH 2/3 V1] mm, page migrate: add MIGRATE_HOTREMOVE type

On 07/04/2012 06:19 PM, Mel Gorman wrote:
> On Wed, Jul 04, 2012 at 03:26:17PM +0800, Lai Jiangshan wrote:
>> MIGRATE_HOTREMOVE is a special kind of MIGRATE_MOVABLE, but it is stable:
>> any page of the type can NOT be changed to the other type nor be moved to
>> the other free list.
>>
>> So the pages of MIGRATE_HOTREMOVE are always movable, this ability is
>> useful for hugepages and hotremove ...etc.
>>
>> MIGRATE_HOTREMOVE pages is the used as the first candidate when
>> we allocate movable pages.
>>
>> 1) add small routine is_migrate_movable() for movable-like types
>> 2) add small routine is_migrate_stable() for stable types
>> 3) fix some comments
>> 4) fix get_any_page(). The get_any_page() may change
>>    MIGRATE_CMA/HOTREMOVE types page to MOVABLE which may cause this page
>>    to be changed to UNMOVABLE.
>>
> 
> Reuse MIGRATE_CMA. 

Will do it.

> Even if the pages are on the movable lists it should
> not be a problem for memory hot-remove.

It does have problem, unmovable pages may be allocated on it.

The movable lists can be used for other type when ohter type is empty.
Or we can rename current movable-lists to movable-preference-lists.

Thanks,
Lai

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