Re: [Xen-users] dom0 - oom-killer - memory leak somewhere ?

[Adrien Urban <adrien.urban@xxxxxxxxxxxxxx>]

On 11/13/11 12:19, Fajar A. Nugraha wrote:
> > On Sun, Nov 13, 2011 at 4:29 PM, Adrien Urban
> > <adrien.urban@xxxxxxxxxxxxxx> wrote:
>> >>
>> >> Hello,
>> >>
>> >> I work in a hosting company, we have tens of Xen dom0 running just
fine,
>> >> but unfortunately we do have a few that get out of control.
>> >>
>> >> Reported behaviour :
>> >> - dom0 uses more and more memory
>> >> - no process can be found using that memory
> >
> > Does the dom0 also serve as some kind of file server (e.g. nfs, web)
> > with lost of files (e.g. several hundred GBs)?
> >
> > If yes, you might need to set /proc/sys/vm/vfs_cache_pressure to 1000
> > (or any value over 100). More details:
> >
http://rackerhacker.com/2008/12/03/reducing-inode-and-dentry-caches-to-keep-oom-killer-at-bay/
> >

Hello,

Thanks to point it out, unfortunately, it doesn't seem to be the case.

The Dom0 don't have anything running but xen, lvm, and some monitoring
services (munin, and nrpe).

I tried to do what is mentioned on this page, but didn't get any real
down in memory usage.


I tried to check slabs and compare between 2 hosts, one working, and the
other not. Couldn't find anything off the chart for our memory leak.


Checking /proc/slabinfo, header states :

# name            <active_objs> <num_objs> <objsize> <objperslab>
<pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata
<active_slabs> <num_slabs> <sharedavail>


I tried to take :
- pagesperslab * active_slabs
- sum up all lines

That should get a total of pages in slabs.



Working host :
# free
             total       used       free     shared    buffers     cached
Mem:        520028     478308      41720          0      72792     204828
-/+ buffers/cache:     200688     319340
Swap:      1044472       6380    1038092


Total pages in slabs: 8416


Non-working host :
# free
             total       used       free     shared    buffers     cached
Mem:       2092892    1501968     590924          0       2296      25200
-/+ buffers/cache:    1474472     618420
Swap:      1998840          0    1998840

Total pages in slabs : 5855


I think those pages are 4k pages. That means slabs are using 34M or 24M
on those hosts. Nothing like the 1GB i can't find.


Regards,
Adrien

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