Samuli Seppänen wrote:
Hello everybody!
I'm having problems with OpenVZ memory management. I have (probably)
read all the Wiki articles there are that touch that subject, and
browsed through the mailing list archives to no avail.
Most of my OpenVZ VPS'es work just fine after a bit of fiddling, but one
of them is misbehaving constantly. It always runs out of memory, no
matter how much I give it. It is running 10 instances of a same server
to give better interactive responsiveness. I was just wondering if the
server program is leaking memory and causing this erratic behavior, or
if there is something wrong with my OpenVZ VPS's configuration.
The physical server runs only this one VPS. The hardware node has 2GB of
RAM plus 2GB of swap. The VPS is given roughly 3.5GB of that if
available (privvmpages limit). It is guaranteed 2.5GB (vmguarpages
barrier). This is FAR more than the server software in question needs,
but still it occasionally (and predictably) runs out of memory.
The strange thing about the VPS is that the HELD values in oomguarpages
and privvmpages are _much_ lower than the MAXHELD values - almost
triple. There should be no usage peaks that should cause this kind of
asymmetry, unless an instance of the server software goes amok.
Yes, privvmpages maxheld shows that software tried to allocate lots of memory
in reality.
And this VE used 874046 pages of RAM+swap (oomguarpages) in the peak, i.e.
~3.4Gb !!!
It looks like accounting doesn't lie and your software really tries
to allocate that much from time to time.
Yes, oomguarpages maxheld is suspiciously high, and probably slows
things down considerably when the server starts swapping.
Have you seen yourself when this was happening and failcounters were increasing?
If you can observe this VE being near the limit,
run top in host system and sort processes by RSS usage.
This will show you which processes consume most of the memory (RSS column).
I'll have to monitor the VPS when it's approaching the privvmpages
limit. Luckily monit will tell me when that is happening :). I'll let
you know what I find out. It starts to seem like the servers in the VPS
are just misbehaving.
BTW, have you did something to make VE use less memory (like server restart)
or the memory usage drops that low itself after some time of being high?
No, I've done nothing special after the latest failure. Sometimes one of
the server instances dies and has to be restarted, but it's only _one_
instance, and there are several others still around.
The VPS's resource information is shown below. The parameters are not
optimized, as you can see, but that not my biggest problem right now :).
So can you see anything wrong with these settings, or should I take a
look at the server software that is running on the VPS?
[EMAIL PROTECTED] ~]# cat /proc/user_beancounters
Version: 2.5
uid resource held maxheld barrier limit failcnt
103: kmemsize 19265157 40765738 183079731 201387704 0
lockedpages 0 0 8939 8939 0
privvmpages 383368 930126 917504 930000 153
shmpages 21647 24239 31099 31099 0
dummy 0 0 0 0 0
numproc 229 524 8000 8000 0
physpages 236810 485688 0 2147483647 0
vmguarpages 0 0 655360 2147483647 0
oomguarpages 382472 874046 310999 2147483647 0
numtcpsock 532 793 8000 8000 0
numflock 18 594 1000 1100 0
numpty 1 4 512 512 0
numsiginfo 0 39 1024 1024 0
tcpsndbuf 3524644 4236356 28258577 61026577 0
tcprcvbuf 3530300 6528712 28258577 61026577 0
othersockbuf 190060 1737340 14129288 46897288 0
dgramrcvbuf 0 41836 14129288 14129288 0
numothersock 204 1169 8000 8000 0
dcachesize 0 0 39977755 41177088 0
numfile 11106 22346 71488 71488 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
numiptent 10 10 200 200 0
[EMAIL PROTECTED] ~]# free
total used free shared buffers cached
Mem: 2073344 2017716 55628 0 66928 954828
-/+ buffers/cache: 995960 1077384
Swap: 2031608 586508 1445100
Anyways, thanks for a great Open Source virtualization project!
you are welcome :@)
Thanks,
Kirill
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