Haltpoll governor (for virtualized systems)

modulename: haltpoll.ko

configname: CONFIG_CPU_IDLE_GOV_HALTPOLL

Linux Kernel Configuration
└─>Power management and ACPI options
└─>CPU Idle
└─>Haltpoll governor (for virtualized systems)
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This governor implements haltpoll idle state selection, to be
used in conjunction with the haltpoll cpuidle driver, allowing
for polling for a certain amount of time before entering idle
state.

Some virtualized workloads benefit from using it.

source code: