max heap usage of a Linux process

[Prasanta Sadhukhan]

Hi,

Can anybody please tell how can I obtain the max. heap usage of a Linux
process?

Thx in advance
Prasanta

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[Markus Rechberger-2]

Hi,

On 11/13/06, Prasanta Sadhukhan <Prasanta.Sadhukhan@...> wrote:
> Hi,
>
> Can anybody please tell how can I obtain the max. heap usage of a Linux
> process?
>

theoretically 3 GB (3/4 of 4gb - which are addressable by 32 bit) on a 32bit machine on a 64bit machine 3/4 of 16exabyte.

cheers,
Markus
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[Bryan Christ]

You should take a look at the man pages for getrlimit()

On Mon, 2006-11-13 at 19:01 +0530, Prasanta Sadhukhan wrote:

> Hi,
>
> Can anybody please tell how can I obtain the max. heap usage of a Linux
> process?
>
> Thx in advance
> Prasanta
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
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[Dan Gary]

unless parent is asking about malloc'd space, then mallinfo() or
malloc_stats() might be what they're looking for, memory profiling the
manual way, gotta love it

On 11/13/06, Markus Rechberger <mrechberger@...> wrote:

> Hi,
>
> On 11/13/06, Prasanta Sadhukhan <Prasanta.Sadhukhan@...> wrote:
> > Hi,
> >
> > Can anybody please tell how can I obtain the max. heap usage of a Linux
> > process?
> >
>
> theoretically 3 GB (3/4 of 4gb - which are addressable by 32 bit) on a 32bit machine on a 64bit machine 3/4 of 16exabyte.
>
> cheers,
> Markus
> -
> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
> the body of a message to majordomo@...
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>

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[Markus Rechberger-2]

Hi,

On 11/13/06, Dan Gary <funkychunkymunky@...> wrote:
> unless parent is asking about malloc'd space, then mallinfo() or
> malloc_stats() might be what they're looking for, memory profiling the
> manual way, gotta love it
>

interesting didn't know that..

though now I have a question about it ..

#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>

int main(){
        char *foo;
        printf("total free space: %d\n",mallinfo().fordblks);
        foo=malloc(500000);
        if(foo){
                printf("successfully allocated!\n");
        } else {
                printf("error allocating!\n");
        }
        printf("arena: %d\n",mallinfo().arena);
        printf("ordblks: %d\n",mallinfo().ordblks);
        printf("max total allocated space: %d\n",mallinfo().usmblks);
        printf("total allocated space: %d\n",mallinfo().uordblks);
        printf("total free space: %d\n",mallinfo().fordblks);

        return 0;
}

outputs:
total free space: 0
successfully allocated!
arena: 0
ordblks: 1
max total allocated space: 0
total allocated space: 0
total free space: 0

If I allocate 50000bytes then it outputs:
total free space: 0
successfully allocated!
arena: 184320
ordblks: 1
max total allocated space: 0
total allocated space: 50008
total free space: 134312

does anyone have an explanation for that?

Markus
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[Bryan Christ]

If you want to know how much you are using, look at uordblks not
ordblks.  The allocator dishes out memory in chunks (not the same has
bytes requested via malloc() so there will most often be some
difference).  

See the GNU documentation at:
http://www.gnu.org/software/libc/manual/html_node/Statistics-of-Malloc.html#Statistics-of-Malloc

BTW, I think the chunk size will always be a multiple of page size (see
the man pages for getpagesize() -- but I haven't give it any thorough
investigation).  Perhaps someone on this list can confirm.

On Mon, 2006-11-13 at 16:59 +0100, Markus Rechberger wrote:

> Hi,
>
> On 11/13/06, Dan Gary <funkychunkymunky@...> wrote:
> > unless parent is asking about malloc'd space, then mallinfo() or
> > malloc_stats() might be what they're looking for, memory profiling the
> > manual way, gotta love it
> >
>
> interesting didn't know that..
>
> though now I have a question about it ..
>
> #include <malloc.h>
> #include <stdio.h>
> #include <stdlib.h>
>
> int main(){
>         char *foo;
>         printf("total free space: %d\n",mallinfo().fordblks);
>         foo=malloc(500000);
>         if(foo){
>                 printf("successfully allocated!\n");
>         } else {
>                 printf("error allocating!\n");
>         }
>         printf("arena: %d\n",mallinfo().arena);
>         printf("ordblks: %d\n",mallinfo().ordblks);
>         printf("max total allocated space: %d\n",mallinfo().usmblks);
>         printf("total allocated space: %d\n",mallinfo().uordblks);
>         printf("total free space: %d\n",mallinfo().fordblks);
>
>         return 0;
> }
>
> outputs:
> total free space: 0
> successfully allocated!
> arena: 0
> ordblks: 1
> max total allocated space: 0
> total allocated space: 0
> total free space: 0
>
> If I allocate 50000bytes then it outputs:
> total free space: 0
> successfully allocated!
> arena: 184320
> ordblks: 1
> max total allocated space: 0
> total allocated space: 50008
> total free space: 134312
>
> does anyone have an explanation for that?
>
> Markus
> -
> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
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[Prasanta Sadhukhan]

Actually, I have the process-pid(s) and I want to find out
programmatically, what's the max heap size that had been consumed by
that process at any given moment(based on user command) from another
process. It seems mallinfo().uordblks will give total occupied size of
memory not the max heap size consumed. Also, how do I use malloc_stats()?

--Prasanta
Dan Gary wrote:

> unless parent is asking about malloc'd space, then mallinfo() or
> malloc_stats() might be what they're looking for, memory profiling the
> manual way, gotta love it
>
> On 11/13/06, Markus Rechberger <mrechberger@...> wrote:
>
>> Hi,
>>
>> On 11/13/06, Prasanta Sadhukhan <Prasanta.Sadhukhan@...> wrote:
>> > Hi,
>> >
>> > Can anybody please tell how can I obtain the max. heap usage of a
>> Linux
>> > process?
>> >
>>
>> theoretically 3 GB (3/4 of 4gb - which are addressable by 32 bit) on
>> a 32bit machine on a 64bit machine 3/4 of 16exabyte.
>>
>> cheers,
>> Markus
>> -
>> To unsubscribe from this list: send the line "unsubscribe
>> linux-c-programming" in
>> the body of a message to majordomo@...
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
> -
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> linux-c-programming" in
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[Glynn Clements]

Prasanta Sadhukhan wrote:

> Actually, I have the process-pid(s) and I want to find out
> programmatically, what's the max heap size that had been consumed by
> that process at any given moment(based on user command) from another
> process.

Then you need to read the files in /proc/<pid>/*. There isn't a system
call to get resource usage for another process.

Note that you won't be able to determine how much of the allocated
heap is free or used; that information is internal to the process, and
isn't visible externally.

--
Glynn Clements <glynn@...>
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[Prasanta Sadhukhan]

Glynn Clements wrote:

>Prasanta Sadhukhan wrote:
>
>  
>
>>Actually, I have the process-pid(s) and I want to find out
>>programmatically, what's the max heap size that had been consumed by
>>that process at any given moment(based on user command) from another
>>process.
>>    
>>
>
>Then you need to read the files in /proc/<pid>/*. There isn't a system
>call to get resource usage for another process.
>
>Note that you won't be able to determine how much of the allocated
>heap is free or used; that information is internal to the process, and
>isn't visible externally.
>
>  
>

thanks. Infact, I used /proc/<pid>/statm to find out total size, RSS and
shared memory from 1st 3 entries. Don't know about the accuracy or not
but that will do. But, this file does not tell about max. heap consumed
by a process nor does /proc/pid/status and I am not able to decipher
/proc/pid/stat. Does anyone knows how to interpret stat file?


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[Al Boldi]

Glynn Clements wrote:
> Prasanta Sadhukhan wrote:
> > Actually, I have the process-pid(s) and I want to find out
> > programmatically, what's the max heap size that had been consumed by
> > that process at any given moment(based on user command) from another
> > process.
>
> Then you need to read the files in /proc/<pid>/*. There isn't a system
> call to get resource usage for another process.

Wow, really?  Reading /proc/<pid>/* is pretty expensive, especially if you
have to do it for 1000's of procs.

That's probably why top is such a cpu-hog.


Thanks!

--
Al


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[Glynn Clements]

Prasanta Sadhukhan wrote:

> > > Actually, I have the process-pid(s) and I want to find out
> > > programmatically, what's the max heap size that had been consumed by
> > > that process at any given moment(based on user command) from another
> > > process.
> >
> > Then you need to read the files in /proc/<pid>/*. There isn't a system
> > call to get resource usage for another process.
> >
> > Note that you won't be able to determine how much of the allocated
> > heap is free or used; that information is internal to the process, and
> > isn't visible externally.
>
> thanks. Infact, I used /proc/<pid>/statm to find out total size, RSS and
> shared memory from 1st 3 entries. Don't know about the accuracy or not
> but that will do. But, this file does not tell about max. heap consumed
> by a process nor does /proc/pid/status and I am not able to decipher
> /proc/pid/stat. Does anyone knows how to interpret stat file?

It's documented in the proc(5) manpage, but I don't think it records
the heap size separately.

Probably the best option is to look in /proc/<pid>/maps for writable
segments with zero for the device and inode numbers (i.e. anonymous
maps).

Also, note that glibc's malloc can use explicit anonymous mmap() to
obtain memory, as well as sbrk(), so there isn't a monolithic "heap"
in the traditional sense.

--
Glynn Clements <glynn@...>
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[Bryan Christ]

If you don't feel like reading proc or want to make things more
portable, use libgtop.

On Tue, 2006-11-14 at 10:57 +0000, Glynn Clements wrote:

> Prasanta Sadhukhan wrote:
>
> > Actually, I have the process-pid(s) and I want to find out
> > programmatically, what's the max heap size that had been consumed by
> > that process at any given moment(based on user command) from another
> > process.
>
> Then you need to read the files in /proc/<pid>/*. There isn't a system
> call to get resource usage for another process.
>
> Note that you won't be able to determine how much of the allocated
> heap is free or used; that information is internal to the process, and
> isn't visible externally.
>

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