1. A method comprising: receiving a host memory subsystem on a host hardware platform, the host memory subsystem including a memory device; establishing respective settings for each of multiple different I/O (input/output) circuit parameters for a target I/O performance characteristic for communication with the memory device by performing the following: setting a respective value for each I/O circuit parameter; generating test traffic with a test engine embedded in the host memory subsystem to stress test the memory device; and measuring an operating margin for the I/O performance characteristic; repeating the setting, generating and measuring for different values of at least one of the I/O circuit parameters so that a plurality of measurements for different I/O circuit parameter settings is made; executing a search function to determine values for each I/O circuit parameter at which the operating margin meets a minimum threshold, wherein the search function extrapolates from the plurality of measurements to a worst case condition; and setting runtime values for the I/O circuit parameters based on the execution of the search function.