Virtual machines running Linux Kernel version 5.13 show an increase in CPU and network performance

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• Virtual machines running Linux Kernel version 5.13 show an increase in CPU and network performance.
• In guest OS tuned logs located at /var/log/tuned/tuned.log, you will see similar entries that is related to those tunable settings (sched_min_granularity_ns and sched_wakeup_granularity).

2021-08-02 04:43:04,771 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu7'. Is the value in the profile correct?
2021-08-02 04:43:04,774 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu2'. Is the value in the profile correct?
2021-08-02 04:43:04,778 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu4'. Is the value in the profile correct?
2021-08-02 04:43:04,781 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu5'. Is the value in the profile correct?
2021-08-02 04:43:04,784 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu3'. Is the value in the profile correct?
2021-08-02 04:43:04,788 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu0'. Is the value in the profile correct?
2021-08-02 04:43:04,791 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu6'. Is the value in the profile correct?
2021-08-02 04:43:04,794 ERROR tuned.plugins.plugin_cpu: Failed to set energy_perf_bias on cpu 'cpu1'. Is the value in the profile correct?
2021-08-02 04:43:04,795 ERROR tuned.plugins.plugin_sysctl: Failed to read sysctl parameter 'kernel.sched_min_granularity_ns', the parameter does not  exist
2021-08-02 04:43:04,795 ERROR tuned.plugins.plugin_sysctl: sysctl option kernel.sched_min_granularity_ns will not be set, failed to read the original value.
2021-08-02 04:43:04,795 ERROR tuned.plugins.plugin_sysctl: Failed to read sysctl parameter 'kernel.sched_wakeup_granularity_ns', the parameter does not exist
2021-08-02 04:43:04,795 ERROR tuned.plugins.plugin_sysctl: sysctl option kernel.sched_wakeup_granularity_ns will not be set, failed to read the original value.
2021-08-02 04:43:04,795 INFO tuned.plugins.plugin_sysctl: reapplying system sysctl
2021-08-02 04:43:04,796 INFO tuned.daemon.daemon: static tuning from profile 'virtual-guest' applied

 

• You will see the below details where the  default 'tuned' profile is different ('throughput-performance') and the value(15ms) of 'sched_wakeup_granularity' is used.

     cat /etc/redhat-release
           Red Hat Enterprise Linux release 8.1 (Ootpa)

           # tuned-adm active
           Current active profile: throughput-performance

          # cat /proc/sys/kernel/sched_wakeup_granularity_ns
          15000000

Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.
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Environment

VMware ESXi 6.7.x
VMware vSphere ESXi 7.0.x
VMware ESXi 6.5.x

Cause

Tuned daemon is the service responsible for updating scheduler tunable setting sched_wakeup_granularity. This issue is due to the use of tuned "throughput-performance" profile, which is the default profile for RHEL distros - as per Red Hat Documentation (refer section 3.2).

Resolution

This is an unsupported configuration. VMware currently does not officially support any Guest OS releases with a 5.13 kernel version.

NOTE: VMware does not publish support for any Guest OS releases that use this kernel. For more information, refer to the VMware Compatibility Guide

Additional Information

For more information refer to Troubleshooting ESX/ESXi virtual machine performance issues
Collecting performance snapshots using vm-support in ESX and ESXi