Unix Programming - shared memory & heap/free store

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Author shared memory & heap/free store
kasthurirangan.balaji@gmail.com

2007-12-14, 1:30 pm

Hi,

I understand that most unix systems provide both shared memory & heap/
free store. I think both of these are limited by the physical ram in
the box. If i do not use shared memory at all, as my application grows
using heap/free store, will the shared memory also be converted to
heap/free store. Is there a way to suppress shared memory and use the
entire available ram to heap/free store.

Thanks,
Balaji.
Rainer Weikusat

2007-12-14, 1:30 pm

kasthurirangan.balaji@gmail.com writes:
> I understand that most unix systems provide both shared memory & heap/
> free store. I think both of these are limited by the physical ram in
> the box.


This depends on the kernel actually being used and the way the system
using this kernel is installed, but generally, it is wrong.

> Is there a way to suppress shared memory and use the
> entire available ram to heap/free store.


On UNIX(*) (and presuambly every other remotely modern general purpose
OS) physical memory is managed by the kernel (or some other piece of
system software) and this implies that applications have no way of
doing it themselves. And this is supposed to mean NO WAY.
Barry Margolin

2007-12-15, 1:41 am

In article
<cd2988e0-9f86-4fca-9fce-75b384d9aaa9@e6g2000prf.googlegroups.com>,
kasthurirangan.balaji@gmail.com wrote:

> Hi,
>
> I understand that most unix systems provide both shared memory & heap/
> free store. I think both of these are limited by the physical ram in
> the box. If i do not use shared memory at all, as my application grows
> using heap/free store, will the shared memory also be converted to
> heap/free store. Is there a way to suppress shared memory and use the
> entire available ram to heap/free store.


I suggest you consult a good book on operating systems and learn how
virtual memory works. Your question doesn't really make sense at all
because of this.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***
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