ESXi CPU usage drops suddenly, and VMs performance are affected
Article ID: 411501
Updated On:
Products
Issue/Introduction
End user reported that on one of the ESXi host, the ESXi host CPU usage dropped suddenly:
Environment
- ESXi 7.0.x
- ESXi 8.0.x
Cause
Check the power management settings in the BIOS :
In the physical server BIOS, view the system profile setting:
Performance by Watt (OS) which means the OS (ESXi) handles the power management.
Review the power management setting the vSphere Client GUI:
Select the ESXi host
Click on the 'Configure' tab and scroll to the 'Hardware' section
Select the 'Overview' section
Ensure the 'Active policy' in the 'Power Management' section is set to 'High performance'
When the Power Management is set to 'High performance', the CPU core P state should be P0, not P13.
In order to view the P state details:
SSH to the ESXi host
Run 'esxtop'
press 'p'
This view displays the C state and P state
If most of the CPU cores are in a P13 state, it is abnormal when the high performance policy is in use.
Example output:
3:28:43am up 13 days 15:40, 1371 worlds, 0 VMs, 0 vCPUs; CPU load average: 0.02, 0.02, 0.02
Power Usage: 193W, Power Cap: N/A
PSTATE MHZ: 2501 2500 2400 2300 2200 2100 2000 1900 1700 1600 1500 1400 1300 1200 1100 1000
CPU %USED %UTIL %C0 %C1 %C2 %P0 %P1 %P11 %P12 %P13 %P14 %P15
0 0.4 1.1 1 99 0 0 0 0 0 100 0 0
1 0.0 0.0 0 100 0 0 0 0 0 100 0 0
2 0.0 0.2 0 100 0 0 0 0 0 100 0 0
3 0.1 0.2 0 100 0 0 0 0 0 100 0 0
4 0.1 0.2 0 100 0 0 0 0 0 100 0 0
5 0.0 0.0 0 100 0 0 0 0 0 100 0 0
6 0.0 0.0 0 100 0 0 0 0 0 100 0 0
7 0.0 0.0 0 100 0 0 0 0 0 100 0 0
8 0.0 0.0 0 100 0 0 0 0 0 100 0 0
9 0.0 0.1 0 100 0 0 0 0 0 100 0 0
10 0.1 0.2 0 100 0 0 0 0 0 100 0 0
11 0.2 0.8 1 99 0 0 0 0 0 100 0 0
12 0.1 0.2 0 100 0 0 0 0 0 100 0 0
13 8.5 17.8 18 82 0 0 0 0 0 100 0 0
14 0.0 0.0 0 100 0 0 0 0 0 100 0 0
15 0.0 0.0 0 100 0 0 0 0 0 100 0 0
16 0.1 0.3 0 100 0 0 0 0 0 100 0 0
17 0.5 1.2 1 99 0 0 0 0 0 100 0 0
18 0.0 0.1 0 100 0 0 0 0 0 100 0 0
19 0.0 0.1 0 100 0 0 0 0 0 100 0 0
20 0.0 0.1 0 100 0 0 0 0 0 100 0 0
21 0.8 1.6 2 98 0 0 0 0 0 100 0 0
22 0.0 0.1 0 100 0 0 0 0 0 100 0 0
23 0.0 0.1 0 100 0 0 0 0 0 100 0 0
24 0.0 0.0 0 100 0 0 0 0 0 100 0 0
25 0.0 0.0 0 100 0 0 0 0 0 100 0 0
26 0.3 1.1 1 99 0 0 0 0 0 100 0 0
27 0.0 0.1 0 100 0 0 0 0 0 100 0 0
28 0.0 0.1 0 100 0 0 0 0 0 100 0 0
29 0.0 0.0 0 100 0 0 0 0 0 100 0 0
30 0.0 0.1 0 100 0 0 0 0 0 100 0 0
Resolution
Initial troubleshooting steps:
Power down the ESXi host
Power the host back up in order to set CPU P states back to P0
Monitor the Esxi host.
If the CPU usage drops continue, there may be an issue with the physical CPU core.
Contact hardware vendor to perform a hardware diagnostic on the host.
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