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Date:      Thu, 23 Mar 2000 01:17:50 GMT
From:      "Kave p.Ram" <hotkaveh@hotmail.com>
To:        questions@freebsd.org
Subject:   memory management in BSD
Message-ID:  <20000323011750.70637.qmail@hotmail.com>

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Hi !
i did some cool/crazy experiments with malloc(3) and free(3) and
watched the whole show in another terminal running ` /usr/bin/top '
it leaves a lot of questions on my mind which concludes that i have
a lot to learn on memory management.

thanx to Alfred Perlstein & Dirk Myers for highlights .

regards,
/kave


>From: Alfred Perlstein <bright@wintelcom.net>
>To: "Kave p.Ram" <hotkaveh@hotmail.com>
>CC: questions@FreeBSD.ORG
>Subject: Re: memory management in BSD
>Date: Wed, 22 Mar 2000 16:05:27 -0800
>
>* Kave p.Ram <hotkaveh@hotmail.com> [000322 15:52] wrote:
> > Hi !
> >
> > I have a question on memory management in FreeBSD .
> > suppose i write a bogus piece of software which just allocates
> > about 5 Mb of memory without freeing it later .
> >
> > if i run this software 10 times then I have allocated totally about
> > 50 Mb of available memory. (but not at once)
> >
> > my question is : if a dumb person like me forget to free the allocated
> > memory dedicated to this piece of code , how does the system (after the 
>end
> > of execution ) knows that those memory areas that this software used is 
>free
> > to reuse ?
>
>When the program exits its memory will be free'd back to the system, if
>the program doesn't exit and the memory is needed, it's likely that the
>memory will be swapped out to disk, if you run out of swap and memory the
>system is likely to get cranky and nuke a process in order to free up
>some resources.
>
>-Alfred


>From: Dirk Myers <dirkm@teleport.com>
>I'm not 100% sure what you're asking, but here's a try at an answer.
>
>The operating system keeps track of which parts of memory it's
>promised to which process.  When the process exits, all the memory
>promised to that process is available to the system.
>
> > thanx for any suggestion :-)
>
>I hope this is what you're asking.  For details, see _The Design
>and Implementation of the 4.4BSD Operating System_.
>
>Dirk	   dirkm@teleport.com
>--
>There's a fine line between cleverness and idiocy.
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