Azure VMs Displaying Incorrect CPU Count in Task Manager

Terence NGAN 0

Three Azure VMs running Windows Server 2016 Datacenter are showing an incorrect CPU count in the operating system. The Azure portal indicates that there are 4 CPUs, but Task Manager only recognizes 2 CPUs. Device Manager displays the correct number of CPUs. Attempts to resolve this issue have included restarting, redeploying, resizing the VMs, and restoring backups as new VMs. Despite these efforts, the Azure portal and Device Manager reflect the correct CPU count, while Task Manager continues to show only 2 CPUs. The memory size is displayed correctly in both the operating system and the portal.

Lijitha B 515 Reputation points

2024-12-12T04:44:29.6566667+00:00

Hi Terence NGAN,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

By default, Azure virtual machines use the "core" scheduler type, which exposes the virtual CPUs to the guest operating system as physical CPUs.
Note: This is a known limitation of Windows Server 2016. This issue is fixed in Windows Server 2019.

Document for reference: https://learn.microsoft.com/en-us/troubleshoot/windows-server/performance/known-ui-limitation-cpu-information?source=recommendations

If you have any further queries, do let us know.

If the answer is helpful, please click "Accept Answer" and "Upvote it."
Terence NGAN 0 Reputation points

2024-12-12T22:17:32.9966667+00:00

I don’t believe I’m encountering any UI limitations with Server 2016. This is because, within the same Azure Resource Group, I have two other Server 2016 Datacenter servers, both of which display the correct number of CPUs for their subscribed sizes.
Lijitha B 515 Reputation points

2024-12-13T10:50:38.36+00:00

Hi Terence NGAN,

Thanks for your response.

Please find the below similar issue article for more information:
https://answers.microsoft.com/en-us/windows/forum/all/task-manager-is-only-showing-only-half-of-my-cores/eb070463-79dd-4ef5-b39b-78c2f041a176

If you have any further queries, do let us know. We are happy to assist you.

Thank you.
Lijitha B 515 Reputation points

2024-12-17T09:15:59.9666667+00:00

Hi Terence NGAN,

Hope you are doing well!

Just checking in to see if you have got a chance to see the comment posted in resolving the issue. If you have any further updates on this issue, please feel free to reach out!

Thank you!
Terence NGAN 0 Reputation points

2024-12-17T13:51:43.5933333+00:00

Hi Lihitha,

I checked your suggested post, but it did not help resolve my issue. In my affected VMs, I have no check mark on the number of processors in System Configuration. Even if I check, it only shows 2 CPUs available for selection, whereas my Azure subscription size is 4 CPUs.
Lijitha B 515 Reputation points

2024-12-18T13:45:37.15+00:00

Hi Terence NGAN,

Thanks for coming back to us again!

Note: After unchecking the number of processors in the system configuration, please restart the virtual machine. Once the VM has restarted, log in and check the Task Manager.

I have deployed a Standard Ds3 v2 (4 CPUs, 14 GiB memory) virtual machine with Windows (Windows Server 2016 Datacenter) and it shows 4 processors in the task manager and checking the number of processors shows 4 processors. You can see the screenshot mentioned below:

If you have any further queries, do let us know.

Thank you!
Terence NGAN 0 Reputation points

2024-12-18T14:38:43.0166667+00:00

Hi Lihitha,

Thanks for your response, very appreciated.

First, I do restart restarts the three affected servers many times, issue persists.

Last weekend, I even try restored backup from one of the servers as new VM, start it up, issue persists. Then I try to in-place upgrade OS to server 2022 Datacenter, upgrade is successful, but issue is not resolved.

You can see the screenshot below
Lijitha B 515 Reputation points

2024-12-20T07:44:24.4566667+00:00
Hi Terence NGAN ,

Thanks for your response again!

Based on screenshots i suggest few steps you can take to troubleshoot the issue:

The VM "BHCLAZBTV001" is configured with 4 vCPUs and 32 GiB of memory. Task manager Shows 8 cores and 16 logical processors, which seems correct for the VM size. server manager Confirms the operating system and other details.

Given that Task Manager shows the correct number of cores and logical processors, but you mentioned it previously showed only 2 CPUs, it seems the issue might be intermittent or related to how Task Manager interprets the CPU configuration.

Some additional steps to try:

Check BIOS/UEFI Settings: Ensure that the VM's BIOS/UEFI settings are configured correctly. Sometimes, settings related to CPU cores can affect how the operating system detects them.

Update Drivers: Make sure all drivers, especially those related to the CPU and chipset, are up to date. This can sometimes resolve discrepancies in hardware reporting.

Use System Information Tool: Open the System Information tool (msinfo32.exe) and check the Processor section. This tool can provide a more detailed view of the CPU configuration.

Check for Windows Updates: Ensure that the operating system is fully updated. Sometimes, updates can resolve issues with hardware detection.

Review Event Logs: Check the Windows Event Viewer for any errors or warnings related to the CPU or hardware. This can provide clues about what might be causing the issue.

If you are still facing issues, please provide some screenshots and details in the "comments" and I would be happy to help you. Thank you again for your time and patience throughout this issue.
Lijitha B 515 Reputation points

2024-12-23T09:01:02.0233333+00:00

Hi Terence NGAN ,

I wanted in to see if you have got a chance to see the comment posted in resolving the issue. If you have any further updates on this issue, do let us know.

Thank you!

2 answers

Przemysław Kuczyński 0 Reputation points

2025-03-06T14:48:14.2033333+00:00

Its related with

Mitigation for Transaction Asynchronous Abort vulnerability, Microarchitectural Data Sampling, Spectre, Meltdown, MMIO, Speculative Store Bypass Disable (SSBD), and L1 Terminal Fault (L1TF) with Hyper-Threading disabledreg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v FeatureSettingsOverride /t REG_DWORD /d 8264 /f

Value 3 is default

https://support.microsoft.com/en-us/topic/kb4072698-windows-server-and-azure-stack-hci-guidance-to-protect-against-silicon-based-microarchitectural-and-speculative-execution-side-channel-vulnerabilities-2f965763-00e2-8f98-b632-0d96f30c8c8e
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Przemysław Kuczyński 0 Reputation points

2025-03-06T14:49:01.4233333+00:00

Its related with

Mitigation for Transaction Asynchronous Abort vulnerability, Microarchitectural Data Sampling, Spectre, Meltdown, MMIO, Speculative Store Bypass Disable (SSBD), and L1 Terminal Fault (L1TF) with Hyper-Threading disabledreg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v FeatureSettingsOverride /t REG_DWORD /d 8264 /f

Value 3 is default

https://support.microsoft.com/en-us/topic/kb4072698-windows-server-and-azure-stack-hci-guidance-to-protect-against-silicon-based-microarchitectural-and-speculative-execution-side-channel-vulnerabilities-2f965763-00e2-8f98-b632-0d96f30c8c8e
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Azure VMs Displaying Incorrect CPU Count in Task Manager

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