Memory management in Cygwin

Memory management in Cygwin

[Alex]

Hi all!
I'm interested to know if C/C++ compilers in Cygwin somehow optimize
memory allocation/deallocation routines like getting large blocks from
OS and then redistributing small portions to the program.
Thanks for help!


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Re: Memory management in Cygwin

[Mumit Khan]

On Sun, 19 Mar 2000, Alex wrote:

> I'm interested to know if C/C++ compilers in Cygwin somehow optimize
> memory allocation/deallocation routines like getting large blocks from
> OS and then redistributing small portions to the program.
> Thanks for help!

It's not the compilers, but rather the runtime that manage the memory
pools, and yes, Cygwin's memory manager does do pool optimization just
like every other `malloc' package out there.

Cygwin's malloc is based on, as far as I can tell, Doug Lea's public
domain implementation. See his homepage http://g.oswego.edu/index.html
for the design document (go down to the "Software" section).

Regards,
Mumit



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Re: Memory management in Cygwin

[Alex]

Mumit Khan wrote:

> On Sun, 19 Mar 2000, Alex wrote:
>
> > I'm interested to know if C/C++ compilers in Cygwin somehow optimize
> > memory allocation/deallocation routines like getting large blocks from
> > OS and then redistributing small portions to the program.
> > Thanks for help!
>
> It's not the compilers, but rather the runtime that manage the memory
> pools, and yes, Cygwin's memory manager does do pool optimization just
> like every other `malloc' package out there.
>
> Cygwin's malloc is based on, as far as I can tell, Doug Lea's public
> domain implementation. See his homepage http://g.oswego.edu/index.html
> for the design document (go down to the "Software" section).
>
> Regards,
> Mumit

 Thanks for help, but it still isn't clear for me, how the memory management
is done in the programs compiled in Cygwin. How about executables build with
-mno-cygwin option? As I know they don't use any runtime libraries. Does the
linker put memory optimization code in them?



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Re: Memory management in Cygwin

[Mumit Khan]

On Wed, 22 Mar 2000, Alex wrote:

>  Thanks for help, but it still isn't clear for me, how the memory management
> is done in the programs compiled in Cygwin. How about executables build with
> -mno-cygwin option? As I know they don't use any runtime libraries. Does the
> linker put memory optimization code in them?

Programs compiled/linked with -mno-cygwin are *not* Cygwin apps, and the
memory management in that case is provided by Microsoft's runtime library
(CRTDLL in this particular case).

Other than perhaps a few odd embedded systems, pretty much everything else 
in the world uses runtime libraries.

The linker typically has nothing to do with memory management.

Cygwin/Mingw programs use malloc or some package built on top of it, 
and malloc uses OS-specific hooks to allocate chunks of memory and
manages that on behalf of the user. Doug Lea's excellent paper on
his malloc package talks about this issue, and so do plenty of other
articles and books.

I get the feeling that I haven't a clue as to what information you're 
really after. 

Regards,
Mumit



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