Question Difference between Intel Speed Select vs Speed Shift vs Speed Step?

[Lndswgs]

My understanding was

Speed Select Technology (SST) - Incorporating SST-CP/BF/TF where specific cores clock higher and reduce lower priority, P1 of specific cores increased and reduces for others and high turbo frequency P0n reduces for others respectively. What exactly controls this?

Speed Shift - P-state/Voltage control handed to the HW itself- presumably the BMC? How does this differ to SST?

Speed Step - P-state control happens via the OS e.g. VMware ESXi

Can anyone explain the difference between the three please?

 

[hotaru.hino]

Speed Select Technology is basically something like Ryzen Master, but something that can be automated by the OS to adjust power and performance aspects of the CPU dynamically so that a single computer can handle various workloads. This is mostly targeted for servers so a single server unit can handle multiple kinds of tasks, rather than have servers, each doing a single task. See https://docs.kernel.org/admin-guide/pm/intel-speed-select.html