Re: buddy system

From: chrismiceli (chrismiceli_at_excite.com)
Date: 03/17/04 

Date: 17 Mar 2004 05:57:02 -0800

Kasper Dupont <kasperd@daimi.au.dk> wrote in message news:<4057F932.865F8398@daimi.au.dk>...
> chrismiceli wrote:
> >
> > I am reading "Understanding the Linux Kernel" (2nd edition) and they
> > are describing the buddy system for allocating contiguous blocks of
> > memory. I mustn't be grasping the system, could someone explain it to
> > me. A good resource would be nice as well describing the buddy system.
> > Thanx in advanced.
>
> It is quite simple. Memory allocation is done in
> chunks of 2^n pages of alligned memory. Where n
> can be anything from 0 to some upper limit.
>
> There is a free list for each n, and each time a
> chunk has been released, there is exactly one
> possible other chunk of the same size it could be
> joined with.
>
> In case there is no free chunks of a specific size,
> a larger allocation can be split in two.

I get the concept, but when I look at the code given in the book, I
can't follow it. Particularly the rmqueue function. I understand the
alloc_pages function. Now that I look at the 2.4.26 src, I see the
code is different than the book, I will try to understand this one,
but any further explanation on these functions could be helpful.
Thanx.

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