linux-kernel - [PATCH 0/4] big chunk memory allocator v4

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Date:	Fri, 19 Nov 2010 17:10:33 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	"linux-mm@...ck.org" <linux-mm@...ck.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	minchan.kim@...il.com, Bob Liu <lliubbo@...il.com>,
	fujita.tomonori@....ntt.co.jp, m.nazarewicz@...sung.com,
	pawel@...iak.com, andi.kleen@...el.com, felipe.contreras@...il.com,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>
Subject: [PATCH 0/4] big chunk memory allocator v4

Hi, this is an updated version. 

No major changes from the last one except for page allocation function.
removed RFC.

Order of patches is

[1/4] move some functions from memory_hotplug.c to page_isolation.c
[2/4] search physically contiguous range suitable for big chunk alloc.
[3/4] allocate big chunk memory based on memory hotplug(migration) technique
[4/4] modify page allocation function.

For what:

  I hear there is requirements to allocate a chunk of page which is larger than
  MAX_ORDER. Now, some (embeded) device use a big memory chunk. To use memory,
  they hide some memory range by boot option (mem=) and use hidden memory
  for its own purpose. But this seems a lack of feature in memory management.

  This patch adds 
	alloc_contig_pages(start, end, nr_pages, gfp_mask)
  to allocate a chunk of page whose length is nr_pages from [start, end)
  phys address. This uses similar logic of memory-unplug, which tries to
  offline [start, end) pages. By this, drivers can allocate 30M or 128M or
  much bigger memory chunk on demand. (I allocated 1G chunk in my test).

  But yes, because of fragmentation, this cannot guarantee 100% alloc.
  If alloc_contig_pages() is called in system boot up or movable_zone is used,
  this allocation succeeds at high rate.

  I tested this on x86-64, and it seems to work as expected. But feedback from
  embeded guys are appreciated because I think they are main user of this
  function.

Thanks,
-Kame

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