1. How does the OS (*nix) keeps track of the heap memory allocated to
each
process? If the OS knows the memory consumed by each process, does it
automatically releases the memory upon process termination/kill? if
not, why not  ?

2. What happens when SIGKILL is issued on a process? What clean up the
OS does?

TIA

~ gau

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gaurish.panse@gmail.com writes:

> 1. How does the OS (*nix) keeps track of the heap memory allocated to
> each
> process? If the OS knows the memory consumed by each process, does it
> automatically releases the memory upon process termination/kill? if
> not, why not  ?
>
> 2. What happens when SIGKILL is issued on a process? What clean up the
> OS does?

Quite interesting questions.  You'll learn a great deal answering them...

You can either read some books, there are very good unix books,
or read the sources of some unix kernel. You've got the choice between
a number of them, ranging from linux, freebsd and other *bsd, minix,
mach, etc.  I assume you're able to find these sources on the web...

--
__Pascal Bourguignon__                     http://www.informatimago.com/

"By filing this bug report you have challenged the honor of my
family. Prepare to die!"

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gaurish.panse@gmail.com wrote:
# 1. How does the OS (*nix) keeps track of the heap memory allocated to
# each
# process? If the OS knows the memory consumed by each process, does it
# automatically releases the memory upon process termination/kill? if
# not, why not  ?

The system knows all pages in your virtual memory. The simplest and
oldest way to extend the data segment is the break value (brk() or
sbrk()). Unices are also now offering more direct control for VM maps.
A process's pages are released when it exits, but those pages might
be shared and remain with other processes. IPC shared memory segments
remain until deleted.

# # 2. What happens when SIGKILL is issued on a process? What clean up the
# OS does?

It does something akin to forcing an _exit call.

--
SM Ryan http://www.rawbw.com/~wyrmwif/
The whole world's against us.

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