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From: Graham Perkins <gperkins@dmu.ac.uk>
Subject: Re: IMPORTANT : BUDDY SYSTEM PROJECT ??????
Date: 1997/09/29
Message-ID: <342FD143.86@dmu.ac.uk>#1/1
X-Deja-AN: 276430096
References: <342813A1.EDE1B5BD@umac.mo>
Organization: De Montfort University Milton Keynes
Reply-To: gperkins@dmu.ac.uk
Newsgroups: 
 hk.comp.pc,hk.comp.software,comp.lang.ada,comp.lang.modula2,comp.lang.c,comp.lang.c++,comp.lang.java.help
Date: 1997-09-29T00:00:00+00:00
List-Id: <comp.lang.ada>


Eric , Chow Hoi Ka wrote:
> Who know what is BUDDY SYSTEM in OS ????
> Who have the information about BUDDY SYSTEM ???

The "Binary Buddy System" is used in some operating systems
for managing the allocation of memory space to processes.

Rather than maintaining a sequential list of free blocks,
the free space manager keeps a binary tree.  Initial space
is made into a single block, allocation involves splitting
it into two "budies" until suitable a size block is generated.
 
This scheme pays off when processes release memory.  A newly
released block can be quickly co-alesced with its buddy (if
its buddy is also free) since the buddies address can be 
obtained by flipping bit N of the block.  (where N is log
base 2 of the block's size).

You must read an operating system book to discover more detail.

> Who have some source codes in Ada, C/C++, Modula2 or Java of BUDDY
> SYSTEM ????

The people who implement operating systems.  and they probably
didn't use Modula-2 or Ada or C++ or Java