memory allocation

memory allocation

[zhaobin xv]

Hi
As I know in C :
a. Global and static variables locate at data segment
b. When a function is called, memory is allocated on the stack to hold
parameter values, local variables, and the address of the calling
function
c. the struct is aligned based on the greatest alignment requirement
of it's members.
I want to know what these base on to define?
Are there some manual or book about these?

Re: memory allocation

[Ian Lance Taylor]

On Mon, Sep 16, 2013 at 1:43 AM, zhaobin xv <xvzhaobin@gmail.com> wrote:
>
> As I know in C :
> a. Global and static variables locate at data segment
> b. When a function is called, memory is allocated on the stack to hold
> parameter values, local variables, and the address of the calling
> function
> c. the struct is aligned based on the greatest alignment requirement
> of it's members.
> I want to know what these base on to define?
> Are there some manual or book about these?

This question is not appropriate for the mailing list gcc@gcc.gnu.org,
which is for the development of GCC itself.  It would be appropriate
for gcc-help@gcc.gnu.org.  Please take any followups to gcc-help.
Thanks.

The document you are looking for is generally called the ABI for the
target processor and operating system.  There are different ABIs for
each processor, and different operating systems on each processor also
have different ABIs.  If you tell us which specific processor and
operating system you are interested in we may be able to point you at
the ABI document for that target.

Ian

re: memory allocation

[Dan Kegel]

Laczó Tibor wrote:
[ In Redhat Linux, how come calling delete on objects in C++
   doesn't return memory to the operating system?  Even after
   my program deletes all its big objects, RSS doesn't shrink. ]

That's an FAQ.  http://www.lysator.liu.se/c/c-faq/c-3.html says
Q. I have a program which mallocs but then frees a lot of memory,
but memory usage (as reported by ps) doesn't seem to go back down.
A. Most implementations of malloc/free do not return freed memory to
the operating system (if there is one), but merely make it available
for future malloc calls within the same process.

glibc's manual also mentions this:
http://www.gnu.org/manual/glibc-2.2.5/html_node/Freeing-after-Malloc.html#Freeing%20after%20Malloc
which says
"Occasionally, free can actually return memory to the operating system
and make the process smaller. Usually, all it can do is allow a
later call to malloc to reuse the space. In the meantime,
the space remains in your program as part of a free-list used internally by malloc."

Please take this discussion to gcc-help@gcc.gnu.org
or maybe comp.lang.c++.

gcc@gcc.gnu.org is for gcc maintainers, not users.
- Dan

-- 
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045

Re: memory allocation

[Gerald Pfeifer]

On Fri, 12 Sep 2003, [iso-8859-2] Laczó Tibor wrote:
> What is the problem?

That you have used a list which is not appropriate for this kind of
questions.

This list is neither on programming, nor on the Linux kernel, nor
on the GNU/Linux system, but on the development _of_ (not _with_)
GCC.

Gerald
-- 
Gerald Pfeifer (Jerry)   gerald@pfeifer.com   http://www.pfeifer.com/gerald/

memory allocation

[Laczó Tibor]

Hi!

I use Redhat Linux.
I have made a C++ program that uses a lot of memory. In the program i 
have many objects. After the use of these object i use the 'delete' 
command to deallocate the memory used by them.

I monitor the program during its working with the 'TOP' command.
The RSS value increases to 500-600M. The program ends his Job, but it 
doesn't terminate, it is just in a pending status. But the RSS value is 
still 500-600M.
The big objects are deleted in the program under the pending status.

What is the problem?

thanks,
Tibor