Abstract: A method, a computer program product, and a system are provided that handles host requests on a hardware security module (HSM). The method includes selecting a domain with a longest wait time with a host request for the HSM and selecting an oldest host request requested by the domain. The method also includes determining a hardware engine type required to process the oldest host request and determining a saturation level of the hardware engine type exceeds a saturation threshold. The method further includes selecting a second host request requested by the domain that uses a different hardware engine type based on the saturation level exceeding the saturation threshold and processing the second host request using the different hardware engine type of the HSM. The method further includes selecting unprocessed host requests of the domains to continuously provide efficient selection of those host requests to the HSM.