Hi

This patch removes bitmap from buddy allocator used in
alloc_pages()/free_pages() in the kernel 2.6.8.1.

Currently, Linux's page allocator uses bitmaps to record an order
of a free page.
This patch removes bitmap from buddy allocator, and uses
page->private field to record an order of a page.

My purpose is to reduce complexity of buddy allocator, when we want to
hotplug memory. For memory hotplug, we have to resize memory management
structures. Major two of them are mem_map and bitmap.If this patch removes
bitmap from buddy allocator, resizeing bitmap will be needless.

I tested this patch on my small PC box(Celeron900MHz,256MB memory)
and a server machine(Xeon x 2, 4GB memory).

Patch is divided into 4 parts
p01 .....  for include files
p02 .....  for initialization of zone
p03 .....  for alloc_pages()
p04 .....  for free_pages()

Note:
This patch records an order of a page in page->private field, in
page->private = ~order manner.
This is because there are pages which is not in buddy allocator and is its
page_count(page)==0.

I'm not convinced that page->private is not used while page_count(page) == 0.
If used, this patch will have a problem.

Thanks
KAME

-- 
--the clue is these footmarks leading to the door.--
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>