Thread (22 messages) 22 messages, 5 authors, 2004-08-24

Re: [Lhms-devel] Re: [RFC] free_area[] bitmap elimination [0/3]

From: Hiroyuki KAMEZAWA <hidden>
Date: 2004-08-21 05:21:42

Hi,
Hirokazu Takahashi wrote:
Hi,

quoted
William Lee Irwin III wrote:

quoted
On Sat, Aug 21, 2004 at 11:31:21AM +0900, Hiroyuki KAMEZAWA wrote:

quoted
This patch removes bitmap from buddy allocator used in
alloc_pages()/free_pages() in the kernel 2.6.8.1.
<snip>
quoted
In my understanding, the patch assumes that size of mem_map[] in each
zone must be multiple of 2^MAX_ORDER, right?
But it doesn't seem it's a big problem, as we can just allocate extra
mem_map[] to round up if it isn't.

I think this may help the buddy allocator to work withtout adding
page_ivs_valid(buddy1).
As you say, I expects the size of zone is multiple of MAX_ORDER.
But IA64 kernel's MAX_ORDER is 4 Giga bytes :(
A Tiger4, an IA64 machine, I use has physical  memory map like this:

0-2G  :
4-8G  :
10-12G:

contiguous mem_map is smaller than MAX_ORDER.

So I think page_is_valid(buddy1) is needed only for a few pages,
which is top of big buddy, in this case.

Hmm.... :(

Thank you,
KAME

-- 
--the clue is these footmarks leading to the door.--
KAMEZAWA Hiroyuki [off-list ref]

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