how to calibrate the cost model parameters

Hello,

             On my system, the estimated query cost has huge difference with the real query cost. For example, a simple select query, the estimated query cost is 100X bigger than real cost,  I think I need to calibrate the cost model parameters below(I still use default value)

#seq_page_cost = 1.0                                 # measured on an arbitrary scale

#random_page_cost = 4.0                         # same scale as above

#cpu_tuple_cost = 0.01                              # same scale as above

#cpu_index_tuple_cost = 0.005               # same scale as above

#cpu_operator_cost = 0.0025                   # same scale as above

I googled it, and only find some suggestions, for example set random_page_cost to 1 or 2 for SSD, however, there is no doc about how to calibrate the cost model parameters to make the estimated query cost close to the real query cost.

Thanks,

James