linux-kernel - Re: [PATCH] Tight check of pfn_valid on sparsemem

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Message-ID: <AANLkTi=Vy0dUSsLmqV8Hwd9TT_m+CAMaVUV+ATOVFJFg@mail.gmail.com>
Date:	Mon, 26 Jul 2010 07:22:45 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Balbir Singh <balbir@...ux.vnet.ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Mel Gorman <mel@....ul.ie>,
	Johannes Weiner <hannes@...xchg.org>,
	Russell King <linux@....linux.org.uk>
Subject: Re: [PATCH] Tight check of pfn_valid on sparsemem - v3

On Mon, Jul 26, 2010 at 2:03 AM, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> On Sun, Jul 25, 2010 at 7:32 PM, Minchan Kim <minchan.kim@...il.com> wrote:
>> Changelog since v2
>>  o Change some function names
>>  o Remove mark_memmap_hole in memmap bring up
>>  o Change CONFIG_SPARSEMEM with CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
>>
>> I have a plan following as after this patch is acked.
>>
>> TODO:
>> 1) expand pfn_valid to FALTMEM in ARM
>> I think we can enhance pfn_valid of FLATMEM in ARM.
>> Now it is doing binary search and it's expesive.
>> First of all, After we merge this patch, I expand it to FALTMEM of ARM.
>>
>> 2) remove memmap_valid_within
>> We can remove memmap_valid_within by strict pfn_valid's tight check.
>>
>> 3) Optimize hole check in sparsemem
>> In case of spasemem, we can optimize pfn_valid through defining new flag
>> like SECTION_HAS_HOLE of hole mem_section.
>>
>
> Is there an assumption somewhere that assumes that page->private will
> always have MEMMAP_HOLE set when the pfn is invalid, independent of
> the context in which it is invoked? BTW, I'd also recommend moving

zzzzz.... I needed sleep.
Will fix and resend.

> over to using set_page_private() and page_private() wrappers (makes
> the code easier to search)

Okay.
Thanks for pointing me out, Balbir.

>
> Balbir
>



-- 
Kind regards,
Minchan Kim
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