+rate_process=str This option controls how fio manages rated IO
+ submissions. The default is 'linear', which submits IO in a
+ linear fashion with fixed delays between IOs that gets
+ adjusted based on IO completion rates. If this is set to
+ 'poisson', fio will submit IO based on a more real world
+ random request flow, known as the Poisson process
+ (https://en.wikipedia.org/wiki/Poisson_process). The lambda
+ will be 10^6 / IOPS for the given workload.
+