From: "Edmund Horner" <ejrh AT paradise DOT net DOT nz>
Newsgroups: comp.os.msdos.djgpp
References: <384411007 DOT 969036196326 DOT JavaMail DOT root AT web305-mc DOT mail DOT com> <969078416 DOT 841936 AT shelley DOT paradise DOT net DOT nz> <969134119 DOT 601345 AT osiris DOT esoterica DOT pt>
Subject: Re: free() DOESN'T return memory to system
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Date: Sun, 17 Sep 2000 15:13:29 +1200
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Yep, you have a point there.  But remember that DPMI, let alone DJGPP,  was
not designed with Windows in mind.  You can try to fix it, but you may find
it tricky...

<almeidaj AT mail DOT com> wrote in message
news:969134119 DOT 601345 AT osiris DOT esoterica DOT pt...
> Hi Edmund,
>
> I think you're wrong about the usefully of returning the memory to the
> system.
> Yes, about Win95, it will give as much as the program needs, BUT only
> until the memory and the swap file aren't EXAUSTED.
> If you have a program that is constantly allocatting memory, and
> freeing it when he no longer needs it, soon the resources are exauted.
> Thus using free() has no impact, purelly a cosmetic sense.
> Returning the memory to the system, will free that resource and enable
> its use.
> Otherwise, deppending on how much ram the computer has, or /and how
> much the virtual memory size is setup in Win95,  the program will
> faile to allocate memory, altough only a small amount of memory is
> actually in use.
> I do know that MS Visual C, uses _heapmin() to solve this drawback.
> BUT i don't want to use it....
> Thanks.
> Advise wellcome.
>
> "Edmund Horner" <ejrh AT paradise DOT net DOT nz> wrote:
>
> >Who's actually asking the question here?  :)
>
> >I don't think you can explicitly return memory to the system, but then, I
am
> >not sure it would be very useful to anyway.  If you're running under DOS,
> >you'll only have one task happening anyway, and if you're under Win9x,
the
> >OS will give each task as much as it needs, anyway.
>
> >But if you're really serious on this, you may be able to extend the DPMI
> >server and the memory functions to allow this...  but I don't think it'll
be
> >easy!
>
> >Edmund.
>
> >"J Almeida" <almeidaj AT mail DOT com> wrote in message
> >news:384411007 DOT 969036196326 DOT JavaMail DOT root AT web305-mc DOT mail DOT com...
> >> Hi,
> >>
> >> Faq15_2.html clearly states that: "When you call free, DJGPP library
> >doesn't
> >> return memory to the system, it just adds it to its internal pool of
free
> >> pages. So, from the point of view of the DPMI server, these pages are
not
> >> "free"."
> >> My question is:
> >> Isn't there a way to ensure that DJGPP _does_ return memory to the
system?
> >> Like _heapmin() in MS Visual C.
> >> Can someone help?
> >> Thanks.
> >>
> >>
> >> ______________________________________________
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>
>