linux-kernel - Re: [RFC][PATCH 3/3] alloc contig pages with migration.

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Date:	Mon, 18 Oct 2010 14:31:08 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH 3/3] alloc contig pages with migration.

On Mon, 18 Oct 2010 14:18:52 +0900
Minchan Kim <minchan.kim@...il.com> wrote:
> >
> >> > + *
> >> > + * Search an area of @size in the physical memory map and checks wheter
> >>
> >> Typo
> >> whether
> >>
> >> > + * we can create a contigous free space. If it seems possible, try to
> >> > + * create contigous space with page migration. If no_search==true, we just try
> >> > + * to allocate [hint, hint+size) range of pages as contigous block.
> >> > + *
> >> > + * Returns a page of the beginning of contiguous block. At failure, NULL
> >> > + * is returned. Each page in the area is set to page_count() = 1. Because
> >>
> >> Why do you mention page_count() = 1?
> >> Do users of this function have to know it?
> >
> > A user can free any page within the range for his purpose.
> 
> I think it's not a good idea if we allow handling of page by page, not
> for page-chunk requested by user.
> By mistake, free_contig_pages could have a trouble to free pages.
> Why do you support the feature?  Do you have any motivation?
> 
No big motivation.

Usual pages are set up by prep_compund_page(page, order), but it is pages smaller
than MAX_ORDER.  Then, I called prep_new_page() one by one.
And I don't think some new prep_xxxx_page() is required.

If you requests, ok, I'll add one.


Thanks,
-Kame

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