[gpfsug-discuss] mmsysmon.py revisited
Mathias Dietz
MDIETZ at de.ibm.com
Thu Jul 20 10:30:50 BST 2017
Jonathon,
its important to separate the two issues "high CPU consumption" and "CPU
Jitter".
As mentioned, we are aware of the CPU jitter issue and already put several
improvements in place. (more to come with the next release)
Did you try with a lower polling frequency and/or enabling clock alignment
as Mike suggested ?
Non-MPI workloads are usually not impacted by CPU jitter, but might be
impacted by high CPU consumption.
But we don't see such such high CPU consumption in the lab and therefore
ask affected customers to get in contact with IBM support to find the root
cause.
Kind regards
Mathias Dietz
IBM Spectrum Scale - Release Lead Architect and RAS Architect
gpfsug-discuss-bounces at spectrumscale.org wrote on 07/19/2017 07:52:14 PM:
> From: Jonathon A Anderson <jonathon.anderson at colorado.edu>
> To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
> Date: 07/19/2017 07:52 PM
> Subject: Re: [gpfsug-discuss] mmsysmon.py revisited
> Sent by: gpfsug-discuss-bounces at spectrumscale.org
>
> > It might be a problem specific to your system environment or a
> wrong configuration therefore please get in contact with IBM support
> to analyze the root cause of the high usage.
>
> I suspect it?s actually a result of frequent IO interrupts causing
> jitter in conflict with MPI on the shared Intel Omni-Path network,
> in our case.
>
> We?ve already tried pursuing support on this through our vendor,
> DDN, and got no-where. Eventually we were the ones who tried killing
> mmsysmon, and that fixed our problem.
>
> The official company line of ?we don't see significant CPU
> consumption by mmsysmon on our test systems? isn?t helping. Do you
> have a test system with OPA?
>
> ~jonathon
>
>
> On 7/19/17, 7:05 AM, "gpfsug-discuss-bounces at spectrumscale.org on
> behalf of Mathias Dietz" <gpfsug-discuss-bounces at spectrumscale.org
> on behalf of MDIETZ at de.ibm.com> wrote:
>
> thanks for the feedback.
>
> Let me clarify what mmsysmon is doing.
> Since IBM Spectrum Scale 4.2.1 the mmsysmon process is used for
> the overall health monitoring and CES failover handling.
> Even without CES it is an essential part of the system because
> it monitors the individual components and provides health state
> information and error events.
>
> This information is needed by other Spectrum Scale components
> (mmhealth command, the IBM Spectrum Scale GUI, Support tools,
> Install Toolkit,..) and therefore disabling mmsysmon will impact them.
>
>
> > It?s a huge problem. I don?t understand why it hasn?t been given
>
> > much credit by dev or support.
>
> Over the last couple of month, the development team has put a
> strong focus on this topic.
>
> In order to monitor the health of the individual components,
> mmsysmon listens for notifications/callback but also has to do some
polling.
> We are trying to reduce the polling overhead constantly and
> replace polling with notifications when possible.
>
>
> Several improvements have been added to 4.2.3, including the
> ability to configure the polling frequency to reduce the overhead.
> (mmhealth config interval)
>
> See https://www.ibm.com/support/knowledgecenter/en/STXKQY_4.2.3/
> com.ibm.spectrum.scale.v4r23.doc/bl1adm_mmhealth.htm
> In addition a new option has been introduced to clock align the
> monitoring threads in order to reduce CPU jitter.
>
>
> Nevertheless, we don't see significant CPU consumption by
> mmsysmon on our test systems.
>
> It might be a problem specific to your system environment or a
> wrong configuration therefore please get in contact with IBM support
> to analyze the root cause of the high usage.
>
> Kind regards
>
> Mathias Dietz
>
> IBM Spectrum Scale - Release Lead Architect and RAS Architect
>
>
>
> gpfsug-discuss-bounces at spectrumscale.org wrote on 07/18/2017
07:51:21 PM:
>
> > From: Jonathon A Anderson <jonathon.anderson at colorado.edu>
> > To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
> > Date: 07/18/2017 07:51 PM
> > Subject: Re: [gpfsug-discuss] mmsysmon.py revisited
> > Sent by: gpfsug-discuss-bounces at spectrumscale.org
> >
> > There?s no official way to cleanly disable it so far as I know
yet;
> > but you can defacto disable it by deleting /var/mmfs/mmsysmon/
> > mmsysmonitor.conf.
> >
> > It?s a huge problem. I don?t understand why it hasn?t been given
> > much credit by dev or support.
> >
> > ~jonathon
> >
> >
> > On 7/18/17, 11:21 AM, "gpfsug-discuss-bounces at spectrumscale.org on
> > behalf of David Johnson" <gpfsug-discuss-bounces at spectrumscale.org
> > on behalf of david_johnson at brown.edu> wrote:
> >
> >
> >
> >
> > We also noticed a fair amount of CPU time accumulated by
> mmsysmon.py on
> > our diskless compute nodes. I read the earlier query, where it
> > was answered:
> >
> >
> >
> >
> > ces == Cluster Export Services, mmsysmon.py comes from
> > mmcesmon. It is used for managing export services of GPFS. If it
is
> > killed, your nfs/smb etc will be out of work.
> > Their overhead is small and they are very important. Don't
> > attempt to kill them.
> >
> >
> >
> >
> >
> >
> > Our question is this ? we don?t run the latest ?protocols",
our
> > NFS is CNFS, and our CIFS is clustered CIFS.
> > I can understand it might be needed with Ganesha, but on
> every node?
> >
> >
> > Why in the world would I be getting this daemon running on all
> > client nodes, when I didn?t install the ?protocols" version
> > of the distribution? We have release 4.2.2 at the moment.
How
> > can we disable this?
> >
> >
> > Thanks,
> > ? ddj
> >
> >
> > _______________________________________________
> > gpfsug-discuss mailing list
> > gpfsug-discuss at spectrumscale.org
> > http://gpfsug.org/mailman/listinfo/gpfsug-discuss
>
>
>
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