Re: total memory of children processes

[Jan-Henrik Haukeland]

Christian, do you thing you can you fix this? and if you can, will you
be able to fix it before early next week?

Does anyone have access to Solaris and can check if this problem occur
there also?



Martin Pala <address@hidden> writes:

> I see the same problem on my station too:
>
> unicorn:~/cvs/monit# ps -leaf
> F S UID        PID  PPID  C PRI  NI ADDR SZ WCHAN  STIME TTY
> TIME CMD
> 1 S root      4890     1  0  69   0 -  2604 rt_sig 18:23 ?
> 00:00:00 /usr/sbin/slapd
> 1 S root      4891  4890  0  69   0 -  2604 poll   18:23 ?
> 00:00:00 /usr/sbin/slapd
> 1 S root      4892  4891  0  69   0 -  2604 select 18:23 ?
> 00:00:00 /usr/sbin/slapd
> 1 S root      4913  4891  0  69   0 -  2604 rt_sig 18:24 ?
> 00:00:00 /usr/sbin/slapd
>
> unicorn:~/cvs/monit# ./monit -c /etc/monitrc status
> Process 'slapd' is running with pid [4890]
>         Uptime: 3m  CPU: 0.0% Memory w/o children: 0.8% [2604kB]
>         Children: 3 Memory w/ children: 3.2% [10416kB]
>         Monitoring status: monitored
>
> As you can see, the reported size is sum of RSS off all threads
> (4*2604=10416). This is not correct result, because 2604kB is memory
> shared by threads (LinuxThreads reports each thread with its PID and
> size, but the memory is shared).
>
>
> Note: this is not related to /proc/kcore patch - it only replaced
> method for available memory detection (instead of kcore size it is
> read from /proc/meminfo - the result is the same) => this is
> standalone problem (bug).
>
> Martin
>
>
> Arkadiusz Miskiewicz wrote:
>
>>Hi,
>>
>>Total memory of children processes seems miscalculated:
>> Event: total mem amount of 12193680kB matches resource limit [total
>> mem amount>512001kB]
>>
>>ok but this machine has only 512MB ram and 2GB of swap.
>>
>> The problem seems be that only rss (resident set size) value is
>> used. rss also includes memory shared between processes.
>>
>>IMO algoritm to calculate total mem amount should looke like:
>>
>> rss of parent + (rss of first child - shared mem, rss of second
>> chold - shared mem and so on). It's still not perfect because we
>> don't know between which processes that memory is shared but it's
>> much better than adding whole rss.
>>
>>shared memory can be found in /proc/$pid/statm.
>>
>>On my server for httpd proces it's:
>>address@hidden root]# pmap -x 22746 |less
>>22746:   httpd -4
>>Address       kB Resident Shared Private Permissions       Name
>>00110000      80       -       0      80 read/exec         ld-2.2.5.so
>>00124000       4       -       0       4 read/write        ld-2.2.5.so
>>00125000       8       -       0       8 read/write         [ anon ]
>>00128000       4       -       0       4 read/exec         mod_asis.so
>>[...]
>>01142000     980       -     980       0 read/write        mod_jk2.shm
>>01237000     980       -     980       0 read/write        mod_jk2.shm
>> 0132c000     508       -     508       0 read/write
>> SYSV00000000 (deleted)
>> 013ab000     364       -     364       0 read/write
>> SYSV00000000 (deleted)
>>08048000     212       -       0     212 read/exec         httpd
>>0807d000      32       -       0      32 read/write        httpd
>>08085000   63820       -       0   63820 read/write/exec    [ anon ]
>> 40000000   32768       -   32768       0 read/write
>> SYSV00000000 (deleted)
>> 42000000   32768       -   32768       0 read/write
>> SYSV00000000 (deleted)
>>bfff5000      44       -       0      44 read/write/exec    [ anon ]
>>--------  ------  ------  ------  ------
>>total kB  148912       -   71360   77552
>>
>> so almost half of memory used by this process is shared between
>> httpd (and other) processes...
>>
>>Comments?
>>
>
>
>
>
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-- 
Jan-Henrik Haukeland