Re: Memory issue on FreeBSD

Hi,

I just add the different memory values together (minus the buffers).
Usually this sums up (+/-) to the installed memory size, at least on my
other machines. I found a thread similar to my problem here [1], but no
solution. I don't mind top showing false values, but if there's a larger
problem behind this, then I really want to solve it.

Top is really just an indicator for this issue, it's also visible in my
munin stats [2]

Below is a output _without_ postgresql running:
Mem: 59M Active, 17G Inact, 3953M Wired, 1325M Cache, 3283M Buf, 8663M Free
Swap: 4096M Total, 828K Used, 4095M Free

and this is after a few hours of running:

Mem: 91M Active, 17G Inact, 3983M Wired, 1526M Cache, 3283M Buf, 155M Free
Swap: 4096M Total, 828K Used, 4095M Free

some memory related sysctl values:
hw.realmem: 34879832064
hw.physmem: 34322804736
hw.usermem: 30161108992

# sysctl vm.vmtotal
vm.vmtotal:
System wide totals computed every five seconds: (values in kilobytes)
===============================================
Processes: (RUNQ: 1 Disk Wait: 0 Page Wait: 0 Sleep: 70)
Virtual Memory: (Total: 1084659688K Active: 10400940K)
Real Memory: (Total: 1616176K Active: 1349052K)
Shared Virtual Memory: (Total: 60840K Active: 14132K)
Shared Real Memory: (Total: 11644K Active: 8388K)
Free Memory Pages: 7263972K

[1]
http://lists.freebsd.org/pipermail/freebsd-stable/2011-January/061247.html
[2]
http://www.gis-hosting.lu/monitor/munin/metrico/bilbo.metrico/memory.html

Am 2012-11-05 15:21, schrieb Achilleas Mantzios:
> How do you measure that smth is missing from top? What values do you add?
> I am currently running 8.3 but we shouldn't be so far apart top-wise.
> What is the reading under SIZE and RES in top for all postgresql processes?
> Take note that shared mem should be recorded for each and every postmaster running.
>
> On Δευ 05 Νοε 2012 14:36:44 Frank Broniewski wrote:
>> Hi,
>>
>> thank you for your feedback. I had a look at those commands and their
>> output, especially in conjunction with the SEGSZ value from icps -am
>>
>> Here's an example output:
>> # ipcs -am
>> Shared Memory:
>> T ID KEY MODE OWNER GROUP CREATOR
>> CGROUP NATTCH SEGSZ CPID LPID ATIME
>> DTIME CTIME
>> m 262144 5432001 --rw------- pgsql pgsql pgsql pgsql
>> 12 8813993984 45512 45512 13:49:28
>> 14:31:29 13:49:28
>>
>> but frankly this tells me nothing. I can tell that the value SEGSZ is
>> right from the start 8813993984 and it doesn't change anymore. The only
>> value that changes is the NATTCH value, I observed a range from 8 to 36
>> there. I agree that the SEGSZ value matches the 8GB shared buffer, but
>> how can I make the connection of my 5GB missing in top? I wonder if this
>> might be the maintenance_work_mem, which is set to 4GB?
>>
>> Many thanks,
>>
>> Frank
>>
>> Am 2012-11-05 12:14, schrieb Achilleas Mantzios:
>>>
>>> ipcs in FreeBSD is a little ... tricky.
>>>
>>> ipcs -M
>>> ipcs -m
>>> ipcs -am
>>>
>>> could be your friends
>>>
>>> On Δευ 05 Νοε 2012 11:22:46 Frank Broniewski wrote:
>>>> Hi,
>>>>
>>>> I am running a PostgreSQL server on FreeBSD. The system has 32GB memory.
>>>> Usually I use top to examine the memory usage of the system. After a
>>>> while, a part, approximately 5GB, vanish from top, so that the memory
>>>> rounds up to 27GB. After restarting PostgreSQL, I have all 32GB again
>>>> available, but then it's already slightly decreasing. It's a standalone
>>>> database server. It has an OpenStreetMap world database running with
>>>> 353GB data (with indices).
>>>>
>>>> Some system information:
>>>> # uname -r
>>>> 9.0-RELEASE-p3
>>>> # pg_ctl --version
>>>> pg_ctl (PostgreSQL) 9.1.6
>>>>
>>>> # cat /boot/loader.conf
>>>> ...
>>>> kern.ipc.semmni=256
>>>> kern.ipc.semmns=512
>>>> kern.ipc.semmnu=256
>>>> kern.ipc.semumr=200
>>>> vm.pmap.shpgperproc=400
>>>> vm.pmap.pv_entry_max=50331648
>>>> ...
>>>>
>>>> # cat /pgdata/data/postgresql.conf
>>>> ...
>>>> default_statistics_target = 50 # pgtune wizard 2012-04-04
>>>> maintenance_work_mem = 4GB # pgtune wizard 2012-04-04
>>>> constraint_exclusion = on # pgtune wizard 2012-04-04
>>>> checkpoint_completion_target = 0.9 # pgtune wizard 2012-04-04
>>>> effective_cache_size = 24GB # pgtune wizard 2012-04-04
>>>> work_mem = 768MB # pgtune wizard 2012-04-04
>>>> wal_buffers = 16MB # pgtune wizard 2012-04-04
>>>> checkpoint_segments = 60 # 20
>>>> shared_buffers = 8GB # pgtune wizard 2012-04-04
>>>> max_connections = 100
>>>> synchronous_commit = off
>>>>
>>>>
>>>> So any help finding out why my system "looses" some RAM is greatly
>>>> appreciated :-) If more information is needed I will gladly provide it.
>>>>
>>>> Frank
>>>>
>>>>
>>>>
>>>>
>>> -
>>> Achilleas Mantzios
>>> IT DEPT
>>>
>>>
>>
>>
>>
> -
> Achilleas Mantzios
> IT DEPT
>
>

--
Frank BRONIEWSKI

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