Mailing List Archive: Xen: Users

Virtualization and monitoring

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mex at di

Jul 11, 2012, 12:15 AM

Post #1 of 8 (395 views)
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Virtualization and monitoring

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

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nd at syndicat

Jul 11, 2012, 12:36 AM

Post #2 of 8 (388 views)
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Re: Virtualization and monitoring [In reply to]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Massimo Canonico <mex [at] di> 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
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nd at syndicat

Jul 11, 2012, 12:38 AM

Post #3 of 8 (376 views)
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Re: Virtualization and monitoring [In reply to]

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
---

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mex at di

Jul 11, 2012, 2:29 AM

Post #4 of 8 (379 views)
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Re: Virtualization and monitoring [In reply to]

Hi Niels,

On 07/11/2012 09:36 AM, Niels Dettenbach (Syndicat IT&Internet) wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
>
>
>
>
> Massimo Canonico <mex [at] di> 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
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> =7tsH
> -----END PGP SIGNATURE-----
>

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mex at di

Jul 11, 2012, 5:38 AM

Post #5 of 8 (375 views)
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Re: Virtualization and monitoring [In reply to]

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 [at] lists
> http://lists.xen.org/xen-users

nd at syndicat

Jul 11, 2012, 5:43 AM

Post #6 of 8 (374 views)
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Re: Virtualization and monitoring [In reply to]

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
---

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nd at syndicat

Jul 11, 2012, 5:45 AM

Post #7 of 8 (377 views)
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Re: Virtualization and monitoring [In reply to]

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
---

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peter.phaal at gmail

Jul 11, 2012, 7:17 AM

Post #8 of 8 (380 views)
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Re: Virtualization and monitoring [In reply to]

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 [at] di> 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.

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