Azure VM Difference between metric Percentage CPU and Insight CPU Utilization

Question

Azure VM Difference between metric Percentage CPU and Insight CPU Utilization

Christian Fabián 156

I can't find a clear explanation on the difference between Percentage CPU metric and CPU Utilization on insights for an Azure VM. I see that values differs between them. Is this documented anywhere?

Thanks

SwathiDhanwada-MSFT 18,996 Reputation points Moderator

2023-04-19T13:47:03.4133333+00:00

@Christian Fabián Did you get chance to look into comments? Kindly revert if you have further questions.
SwathiDhanwada-MSFT 18,996 Reputation points Moderator

2023-04-25T05:30:25.58+00:00

@Christian Fabián Hope the information provided is useful. Let me know if you have further questions.

Accepted answer

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SwathiDhanwada-MSFT 18,996 Reputation points Moderator

2023-04-19T13:47:03.4133333+00:00

@Christian Fabián Did you get chance to look into comments? Kindly revert if you have further questions.
SwathiDhanwada-MSFT 18,996 Reputation points Moderator

2023-04-25T05:30:25.58+00:00

@Christian Fabián Hope the information provided is useful. Let me know if you have further questions.

Answer 1

TP 125.8K Volunteer Moderator

Hi,

Percentage CPU is from the host perspective whereas Insights CPU Utilization is from within the VM perspective.

This is same concept as viewing Task Manager inside of a VM running on Hyper-V and viewing Hyper-V Performance counters on parent partition.

If the above is helpful please click Accept Answer.

Thanks.

-TP

Christian Fabián 156 Reputation points

2023-04-17T16:02:18.3+00:00

Hi TP,

Thanks, just to clarify... Percentage CPU reflects the whole host CPU usage (where multiple VMs could be running) ? So it is not a good metric for monitoring an Azure VM CPU usage?

Thanks,
TP 125.8K Reputation points Volunteer Moderator

2023-04-17T16:54:45.0033333+00:00

Thanks, just to clarify... Percentage CPU reflects the whole host CPU usage (where multiple VMs could be running) ? So it is not a good metric for monitoring an Azure VM CPU usage?

No, Percentage CPU is the VM's CPU usage % from the perspective of the host. The host has a better view as to how much CPU the VM is actually using.

That's not to say the CPU usage from within the VM is a bad metric. It is valuable as well. For example, if the reading from within the VM is consistently 85% that is a good indicator the VM is busy and may need resources even while the reading from the host could be something different like 68%.
TP 125.8K Reputation points Volunteer Moderator

2023-04-27T20:04:50.25+00:00

@Christian Fabián Do my comments make sense? In the one above and my original answer I'm attempting to make the distinction between a metric read at the level of the hypervisor versus a metric read from within a VM.

The resources within a VM are virtual. The hypervisor has control over CPU scheduling, so it knows how much actual processor time is being given to a VM, whereas inside of the VM itself it doesn't know that.

This distinction predates Azure. It exists with Hyper-V, VMWare, XenServer, and other hypervisors as well.
Christian Fabián 156 Reputation points

2023-05-03T21:17:58.5033333+00:00

Hi TP, yes your comments make sense. Thanks for the information, I get know that Percentage CPU is from the host perspective and insights from within and both metric are valuable as from the host perspective the Hypervisor has control of CPU and from within the vm the metric is also useful as high usage could also point to the need of more resources.

Let me know if what I said makes sense.

Answer 2

SwathiDhanwada-MSFT 18,996 Moderator

@Christian Fabián The "Percentage CPU" metric in Azure VMs is a basic metric that shows the percentage of CPU usage for a VM. It is a standard metric that is available for all VMs in Azure and can be viewed in the Azure portal or queried using Azure Monitor. On the other hand, "Insight CPU Utilization" is a more advanced metric that is available through Azure Monitor for VMs that have the Log Analytics agent installed. This metric provides more detailed information about CPU usage, including the percentage of CPU usage broken down by process and the amount of CPU time used by each process. It also provides information about CPU usage over time, allowing you to see trends and patterns in CPU usage.

In summary, "Percentage CPU" is a basic metric that shows overall CPU usage for a VM, while "Insight CPU Utilization" is a more advanced metric that provides more detailed information about CPU usage, including usage by process and over time.

Christian Fabián 156 Reputation points

2023-04-26T23:21:45.99+00:00

Hi Swathi, thanks for the explanation.
I just want to clear things up... I get that Percentage CPU is a basic metric while Insights CPU Utilization is more advanced, but how would I interpret theses differences? And what about alerts? As they are can be configured with the Percentage CPU metric, but I'm not sure if insights CPU Utilization can be used for alerts.

As you see 3 of 4 VMs show same behavior both images except for the VM with "AP-01"

Insights CPU Utilization:

Percentage CPU:
TP 125.8K Reputation points Volunteer Moderator

2023-04-27T09:00:47.9366667+00:00

@Christian Fabián Yes, you can configure alerts for VM Insights CPU Utilization. In your condition you would specify the custom log query. For example, article below gives one example:

https://learn.microsoft.com/en-us/azure/azure-monitor/vm/monitor-virtual-machine-alerts#log-alert-rules-2

Keep in mind with Insights the agent providing the data is running inside of the VM, and is itself using resources such as CPU/RAM/etc.
Elluri Srinivas 1 Reputation point

2023-08-04T06:09:25.0233333+00:00

Hi

Azure metrics showing CPU utilization for a VM is pretty confusing.

when we use metric for CPU percentage(max) and CPU used (Max), we see CPU percentage(max) hitting 100% but the CPU used (Max) is showing below 20%.

Since these specs are at VM level, Assuming CPU used is directly proportional to CPU percentage, But it looks irrelevant.

How can I interpret this? please clarify.

My Setup overview -

My VM is hosting only SQL Server with couple of databases no other application.

In order to troubleshoot the 100% CPU percentage - I started with identifying the activities, Queries that are resource intensive.

Presumed that these queries are using lot of CPU and IO that caused 100% CPU percentage.

But at the same time CPU used (Max) shows very low.

During CPU percentage(max) , working threads also shows minimal.

Now my concern is tuning the queries would help the CPU percentage(max) ?

Thank you

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Azure VM Difference between metric Percentage CPU and Insight CPU Utilization

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