[Users] Fwd: Re: Memory usage

Martin Sivak msivak at redhat.com
Mon Feb 17 08:00:06 EST 2014 

Hi Koen,

can you try the mentioned vdsClient command (vdsClient getVmStats <affected vm>) as soon as you get the warning about negative memory? The one David sent to us does not contain the negative number and we weren't able to find the issue based on it.

Thanks

--
Martin Sivák
msivak at redhat.com
Red Hat Czech
RHEV-M SLA / Brno, CZ

----- Original Message -----
> Any updates about the issue? Because just now, the alarm went off again :-)
> Kind regards,
> 
> Koen
> 
> 
> 2014-02-13 16:55 GMT+01:00 Martin Sivak <msivak at redhat.com>:
> 
> > Thank you.
> >
> > I wonder why mem_total is smaller than balloon_cur (and max). I will have
> > to dig a bit more to see what happened.
> >
> > --
> > Martin Sivák
> > msivak at redhat.com
> > Red Hat Czech
> > RHEV-M SLA / Brno, CZ
> >
> > ----- Original Message -----
> > > ---------- Forwarded message ----------
> > > From: "david van zeebroeck" < david at analytics.brusselsairport.be >
> > > Date: Feb 13, 2014 4:31 PM
> > > Subject: Re: [Users] Memory usage
> > > To: "Martin Sivak" < msivak at redhat.com >
> > > Cc: "Doron Fediuck" < dfediuck at redhat.com >, "Koen Vanoppen" <
> > > vanoppen.koen at gmail.com >, < users at ovirt.org >
> > >
> > > in attachement is the output of vdsclient
> > >
> > >
> > >
> > >
> > > On Thu, Feb 13, 2014 at 2:26 PM, Martin Sivak < msivak at redhat.com >
> > wrote:
> > >
> > >
> > > Hi everybody,
> > >
> > > would it be possible to add the output of vdsClient getVmStats <affected
> > vm
> > > id> from the affected host here and to the bug?
> > >
> > > Also can we please get the bug number that tracks this issue? I could not
> > > find it in BZ.
> > >
> > > --
> > > Martin Sivák
> > > msivak at redhat.com
> > > Red Hat Czech
> > > RHEV-M SLA / Brno, CZ
> > >
> > > ----- Original Message -----
> > > >
> > > >
> > > > ----- Original Message -----
> > > > > From: "Koen Vanoppen" < vanoppen.koen at gmail.com >
> > > > > To: users at ovirt.org
> > > > > Sent: Thursday, February 13, 2014 12:18:24 PM
> > > > > Subject: Re: [Users] Memory usage
> > > > >
> > > > >
> > > > >
> > > > > We can't turn off the memory balloon option because we are running
> > the
> > > > > 3.3.2
> > > > > with the bug of the memory balloon. Thx for the help!
> > > >
> > > > Which balloon bug?
> > > >
> > > > > On Feb 13, 2014 10:51 AM, "Doron Fediuck" < dfediuck at redhat.com >
> > wrote:
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > ----- Original Message -----
> > > > > > From: "René Koch" < rkoch at linuxland.at >
> > > > > > To: "Doron Fediuck" < dfediuck at redhat.com >
> > > > > > Cc: "Koen Vanoppen" < vanoppen.koen at gmail.com >, users at ovirt.org ,
> > > > > > "Martin
> > > > > > Sivak" < msivak at redhat.com >
> > > > > > Sent: Thursday, February 13, 2014 11:16:27 AM
> > > > > > Subject: Re: [Users] Memory usage
> > > > > >
> > > > > > On Thu, 2014-02-13 at 03:49 -0500, Doron Fediuck wrote:
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > > > From: "René Koch" < rkoch at linuxland.at >
> > > > > > > > To: "Doron Fediuck" < dfediuck at redhat.com >
> > > > > > > > Cc: "Koen Vanoppen" < vanoppen.koen at gmail.com >,
> > users at ovirt.org ,
> > > > > > > > "Martin
> > > > > > > > Sivak" < msivak at redhat.com >
> > > > > > > > Sent: Wednesday, February 12, 2014 7:31:47 PM
> > > > > > > > Subject: Re: [Users] Memory usage
> > > > > > > >
> > > > > > > > On Wed, 2014-02-12 at 11:22 -0500, Doron Fediuck wrote:
> > > > > > > > >
> > > > > > > > > ----- Original Message -----
> > > > > > > > > > From: "René Koch" < rkoch at linuxland.at >
> > > > > > > > > > To: "Koen Vanoppen" < vanoppen.koen at gmail.com >
> > > > > > > > > > Cc: users at ovirt.org
> > > > > > > > > > Sent: Wednesday, February 12, 2014 4:18:37 PM
> > > > > > > > > > Subject: Re: [Users] Memory usage
> > > > > > > > > >
> > > > > > > > > > On Wed, 2014-02-12 at 15:14 +0100, Koen Vanoppen wrote:
> > > > > > > > > > > In The GUI, it says it's using 25% of the memory.
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > I guess it's the real value, right?
> > > > > > > > > > The same happened for the memcached vm, someone reported
> > to me
> > > > > > > > > > -
> > > > > > > > > > negative value in REST-API, but correct graph in oVirt
> > webadmin
> > > > > > > > > > GUI.
> > > > > > > > > >
> > > > > > > > > > I fear I have no idea how this can happen - so maybe
> > someone
> > > > > > > > > > else
> > > > > > > > > > can
> > > > > > > > > > help you troubleshoot this issue.
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > 2014-02-12 15:10 GMT+01:00 Koen Vanoppen <
> > > > > > > > > > > vanoppen.koen at gmail.com >:
> > > > > > > > > > > Thanks for the quick respons, but there is no memcached
> > > > > > > > > > > running on that VM.
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Kind regards
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > 2014-02-12 15:06 GMT+01:00 René Koch <
> > rkoch at linuxland.at >:
> > > > > > > > > > >
> > > > > > > > > > > On Wed, 2014-02-12 at 14:55 +0100, Koen Vanoppen
> > > > > > > > > > > wrote:
> > > > > > > > > > > > Dear all,
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > When we monitor one of our machines, we noticed
> > > > > > > > > > > > that
> > > > > > > > > > > there was one vm
> > > > > > > > > > > > that was constantly giving a error of memory
> > > > > > > > > > > > usage.
> > > > > > > > > > > But when we took a
> > > > > > > > > > > > look at it, there is actually nothing wrong with
> > > > > > > > > > > > it.
> > > > > > > > > > > Now we looked
> > > > > > > > > > > > furhter then that. We looked at the API of the
> > > > > > > > > > > machine and noticed
> > > > > > > > > > > > something very strange:
> > > > > > > > > > > >
> > > > > > > > > > > > <statistic
> > > > > > > > > > > >
> > > > > > > > > > >
> > href="/api/vms/3b9aa245-75ff-42e8-b921-1c9ce61826bf/statistics/b7499508-c1c3-32f0-8174-c1783e57bb08"
> > > > > > > > > > >
> > id="b7499508-c1c3-32f0-8174-c1783e57bb08"><name>memory.used</name><description>Memory
> > > > > > > > > > > used (agent)</description><values
> > > > > > > > > > >
> > type="INTEGER"><value><datum>-944892806</datum></value></values><type>GAUGE</type><unit>BYTES</unit>
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > It's a negative...
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Do you have memcached running in this vm?
> > > > > > > > > > >
> > > > > > > > > > > I heard about this issue with memcached, but never
> > > > > > > > > > > tested memcached in
> > > > > > > > > > > my oVirt environment. You get the real usage value
> > > > > > > > > > > with
> > > > > > > > > > > memory.used = memory.installed + memory.used
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Regards,
> > > > > > > > > > > René
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > What could be the problem?
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > Kind regards,
> > > > > > > > > > > >
> > > > > > > > > > > > koen
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > >
> > > > > > > > > Guys,
> > > > > > > > > these values are usually a result of overcommitment mechanism
> > > > > > > > > usage.
> > > > > > > > > For example, if KSM is effective, it will free a lot of
> > memory
> > > > > > > > > pages,
> > > > > > > > > and total-free-committed becomes negative.
> > > > > > > >
> > > > > > > >
> > > > > > > > Thanks a lot for the information.
> > > > > > > >
> > > > > > > >
> > > > > > > > >
> > > > > > > > > This was reported in
> > > > > > > > > https://bugzilla.redhat.com/show_bug.cgi?id=977758
> > > > > > > > > and the engine is using memFree reported by vdsm, which is
> > more
> > > > > > > > > accurate.
> > > > > > > > >
> > > > > > > > > The API reports the old version due to backwards
> > compatibility.
> > > > > > > >
> > > > > > > >
> > > > > > > > I just had a look at the bugzilla report and the RHEV
> > documentation
> > > > > > > > which says "Current memory in bytes used by the virtual
> > machine.".
> > > > > > > > So this means, the reported values are totally useless for
> > > > > > > > monitoring
> > > > > > > > memory usage of a virtual machine if KSM is active. I would
> > expect
> > > > > > > > to
> > > > > > > > get the memory usage of a virtual machine and not how much
> > memory
> > > > > > > > is
> > > > > > > > consumed on the hypervisor (this is pretty useless information
> > for
> > > > > > > > me).
> > > > > > > >
> > > > > > > > Is it planned to report the memory usage in a virtual machine
> > in
> > > > > > > > the
> > > > > > > > API
> > > > > > > > as well?
> > > > > > > >
> > > > > > > >
> > > > > > > > Regards,
> > > > > > > > René
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > > René,
> > > > > > > started digging into this, but it may take some time.
> > > > > > >
> > > > > > > Note that there are 2 memory usage reports; one for the host,
> > > > > > > and another for each VM.
> > > > > > > My response is related to the host, while the original question
> > was
> > > > > > > for the VM. I still think the root cause is the same (ie-
> > related to
> > > > > > > overcommitment; for example the VM may have a balloon inflated),
> > but
> > > > > > > would like to properly check and fix if needed.
> > > > > >
> > > > > >
> > > > > > Yes, I know. So my question was if we can add another value for the
> > > > > > usage in the vm in addition to the usage of the vm on the host.
> > > > > >
> > > > > We'll know once we understand the cause- ie is it a bug needs fixing
> > or
> > > > > should we indeed add another value
> > > > >
> > > > > If you have a setup with this issue, try removing the balloon device
> > > > > and see if it helps / changes.
> > > > >
> > > > > >
> > > > > > >
> > > > > > > In order to make sure we keep track of it, please open a bug
> > with all
> > > > > > > the
> > > > > > > relevant info.
> > > > > > >
> > > > > >
> > > > > > I'll open a bug for this.
> > > > > >
> > > > > Thanks
> > > > >
> > > > > >
> > > > > > > Thanks and keep reporting!
> > > > > > > Doron
> > > > > >
> > > > > >
> > > > > >
> > > > >
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