freebsd stable - Dec 2010 - get ram usage using getrusage()

Hi.

I'm trying to read how much ram an app is using reading
http://unix.derkeiler.com/Mailing-Lists/FreeBSD/stable/2006-03/msg00246.html
from ru.ru_maxrss. While ru.ru_maxrss gives me used accurate ram-usage
when memory increases it doesn't immediately count down when memory is
released.

So I tried to get a more accurate reading using this using
/usr/src/sys/kern/kern_clock.c as example:

struct thread *td;
td = curthread;
p = td->td_proc;
vm = p->p_vmspace;
rss = pgtok(vmspace_resident_count(vm));

Curthread is not defined, I searched google but can't find any references.

But is this the proper way to get an apps memory usage?

-- 
regards
Claus

When lenity and cruelty play for a kingdom,
the gentler gamester is the soonest winner.

Shakespeare

twitter.com/kometen

On Sun, Dec 19, 2010 at 10:51:02PM +0100, Claus Guttesen
wrote:
> I'm trying to read how much ram an app is using reading
>
http://unix.derkeiler.com/Mailing-Lists/FreeBSD/stable/2006-03/msg00246.html
> from ru.ru_maxrss. While ru.ru_maxrss gives me used accurate ram-usage
> when memory increases it doesn't immediately count down when memory is
> released.
> 
> So I tried to get a more accurate reading using this using
> /usr/src/sys/kern/kern_clock.c as example:
> 
> struct thread *td;
> td = curthread;
> p = td->td_proc;
> vm = p->p_vmspace;
> rss = pgtok(vmspace_resident_count(vm));
> 
> Curthread is not defined, I searched google but can't find any
references.
> 
> But is this the proper way to get an apps memory usage?
This question might be better suited for the freebsd-hackers mailing
list.

-- 
| Jeremy Chadwick                                   jdc@parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.               PGP 4BD6C0CB |

Claus Guttesen <kometen@gmail.com> wrote:
 > I'm trying to read how much ram an app is using reading

Could you phrase that question more precisely?
Note that "ram" and "memory" mean different things.
Are you interested in the VM mapped to the process?
Or do you want to know the amount of physical RAM only?
Do you want to include pages that are currently paged
to swap?  Do you want to include shared pages, or only
pages assigned exclusively to your process?  Do you
want to include memory that was free()ed but is still
mapped to your process?  And so on ...

It might be helpful to know *WHY* you are interested
in the app's RAM usage, in order to be able to give the
most appropriate advice.

 >
http://unix.derkeiler.com/Mailing-Lists/FreeBSD/stable/2006-03/msg00246.html
 > from ru.ru_maxrss. While ru.ru_maxrss gives me used accurate ram-usage
 > when memory increases it doesn't immediately count down when memory is
 > released.

What do you mean by "released"?  If you mean free(), that
doesn't necessarily unmap pages from the process.  I think
that the current malloc() implementation uses madvise()
with MADV_FREE (but I'm not 100% sure).  But this is an
implementation detail that applications should not care
about.

 > So I tried to get a more accurate reading using this using
 > /usr/src/sys/kern/kern_clock.c as example:
 > 
 > struct thread *td;
 > td = curthread;
 > p = td->td_proc;
 > vm = p->p_vmspace;
 > rss = pgtok(vmspace_resident_count(vm));
 > 
 > Curthread is not defined, I searched google but can't find any
references.

That's a piece of kernel source code.  It won't work in
user space.

 > But is this the proper way to get an apps memory usage?

I think asking for an app's "memory usage" is not proper in
the first place.  :-)

Best regards
   Oliver

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