Hi, I''ve noticed some weird behaviours on monitoring my physical machines while Virtual Machines (VMs) were running. The cpu load on the physical machine was very low (around 10%), while the load on VM were very high (around 80%). How is it possible? Is there any workaround? Thanks, M
Niels Dettenbach (Syndicat IT&Internet)
2012-Jul-11 07:36 UTC
Re: Virtualization and monitoring
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Massimo Canonico <mex@di.unipmn.it> schrieb:> > >Hi, >I''ve noticed some weird behaviours on monitoring my physical machines >while Virtual Machines (VMs) were running. The cpu load on the physical >machine was very low (around 10%), while the load on VM were very high >(around 80%). > >How is it possible? Is there any workaround?Itt is possible that you''ve measured just the Dom0 CPU load instead of the "real" host machine? best regards, Niels. - -- Niels Dettenbach Syndicat IT&Internet http://www.syndicat.com -----BEGIN PGP SIGNATURE----- Version: APG v1.0.8 iIEEAREIAEEFAk/9LRc6HE5pZWxzIERldHRlbmJhY2ggKFN5bmRpY2F0IElUJklu dGVybmV0KSA8bmRAc3luZGljYXQuY29tPgAKCRBU3ERlZRyiDbunAJoC+D5ShXaN vGzzbbE/mIWkrvvPVwCghGLh91PjpdTcqRLdxGI+X8hhKag=7tsH -----END PGP SIGNATURE-----
Am Mittwoch, 11. Juli 2012, 11:29:03 schrieb Massimo Canonico:> I''ve measured the cpu load by using "top" linux command. I''ve also tried > with some monitoring tools like Munin/Collectd but I always get weird > values.It seems you''ve runned into a typical misunderstanding of the xen architecture. If you use "top" or other system monitorings on Dom0 then you just (!!!) measure the Dom0 parameters / load. Dom0 is just ONE of the xen domains, "just" privileged". There are different ways to get out the machine load out from xen - i.e. xentop. You might compare "top" and "xentop" results on your Dom0 for understanding the difference. hth best regards, Niels. -- --- Niels Dettenbach Syndicat IT & Internet http://www.syndicat.com PGP: https://syndicat.com/pub_key.asc --- _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Hi Niels, On 07/11/2012 09:36 AM, Niels Dettenbach (Syndicat IT&Internet) wrote:> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > > > > > Massimo Canonico <mex@di.unipmn.it> schrieb: > >> >> Hi, >> I''ve noticed some weird behaviours on monitoring my physical machines >> while Virtual Machines (VMs) were running. The cpu load on the physical >> machine was very low (around 10%), while the load on VM were very high >> (around 80%). >> >> How is it possible? Is there any workaround? > Itt is possible that you''ve measured just the Dom0 CPU load instead of the "real" host machine?I''ve measured the cpu load by using "top" linux command. I''ve also tried with some monitoring tools like Munin/Collectd but I always get weird values. All these monitoring tools were running on a linux fedora machine with xen kernel and with xen up and running. The question is: using "top" on the physical machine with xen dom0 up and running will provide me the usage of the dom0 process? Of course, what I need is the cpu load of the real machine. Am I doing it wrong? Thanks, M> > best regards, > > > Niels. > - -- > Niels Dettenbach > Syndicat IT&Internet > http://www.syndicat.com > -----BEGIN PGP SIGNATURE----- > Version: APG v1.0.8 > > iIEEAREIAEEFAk/9LRc6HE5pZWxzIERldHRlbmJhY2ggKFN5bmRpY2F0IElUJklu > dGVybmV0KSA8bmRAc3luZGljYXQuY29tPgAKCRBU3ERlZRyiDbunAJoC+D5ShXaN > vGzzbbE/mIWkrvvPVwCghGLh91PjpdTcqRLdxGI+X8hhKag> =7tsH > -----END PGP SIGNATURE----- >
Hi Niels, On 07/11/2012 09:38 AM, Niels Dettenbach wrote:> Am Mittwoch, 11. Juli 2012, 11:29:03 schrieb Massimo Canonico: >> I''ve measured the cpu load by using "top" linux command. I''ve also tried >> with some monitoring tools like Munin/Collectd but I always get weird >> values. > It seems you''ve runned into a typical misunderstanding of the xen > architecture. > > If you use "top" or other system monitorings on Dom0 then you just (!!!) > measure the Dom0 parameters / load. Dom0 is just ONE of the xen domains, > "just" privileged". > > There are different ways to get out the machine load out from xen - i.e. > xentop. > > You might compare "top" and "xentop" results on your Dom0 for understanding > the difference.Thank you very much for this clarification. Just one more question: are you aware of any monitoring tool able to get out the machine load out from xen (besides xentop)? I''ve tried Munin/Collectd with no luck. Cheers, Massimo> > hth > best regards, > > > > Niels. > > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Am Mittwoch, 11. Juli 2012, 14:38:09 schrieb Massimo Canonico:> Thank you very much for this clarification. > Just one more question: are you aware of any monitoring tool able to get > out the machine load out from xen (besides xentop)? > > I''ve tried Munin/Collectd with no luck.You get all important things out to know from xentop or xm top i.e. to use that output in typical small to enterprise scale monitoring solutions - from a simple shell or perlscipt, over zabbix sensors, cacti, rrdtool up to nagios etc. just a few examples: http://phplens.com/phpeverywhere/?q=node/view/266 http://www.novell.com/coolsolutions/feature/19490.html If you are not able to write your own plugins / "sensors" for your favorite monitoring take a look into their plugin collections. hth cheers, Niels. -- --- Niels Dettenbach Syndicat IT & Internet http://www.syndicat.com PGP: https://syndicat.com/pub_key.asc --- _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Am Mittwoch, 11. Juli 2012, 14:38:09 schrieb Massimo Canonico:> Hi Niels, > Thank you very much for this clarification. > Just one more question: are you aware of any monitoring tool able to get > out the machine load out from xen (besides xentop)? > > I''ve tried Munin/Collectd with no luck...forgot XenMon: http://www.virtuatopia.com/index.php/Xen_Monitoring_Tools_and_Techniques#Monitoring_Xen_Performance_with_XenMon -- --- Niels Dettenbach Syndicat IT & Internet http://www.syndicat.com PGP: https://syndicat.com/pub_key.asc --- _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Massimo, You might want to try installing a Host sFlow agent on Dom0 - it will export the stats that xentop displays using the sFlow standard. You can use tools like Ganglia or sFlowTrend to graphically plot the data, or roll your own using the sflowtool CLI utility. http://blog.sflow.com/2012/01/using-ganglia-to-monitor-virtual.html http://blog.sflow.com/2010/10/sflowtrend-adds-server-performance.html Peter On Wed, Jul 11, 2012 at 5:38 AM, Massimo Canonico <mex@di.unipmn.it> wrote:> Thank you very much for this clarification. > Just one more question: are you aware of any monitoring tool able to get out > the machine load out from xen (besides xentop)? > > I''ve tried Munin/Collectd with no luck.