How the util of iostat is computed?

Question

iostat -x -d 

can display many i/o statistic info. For util of iostat, the explanation is :

Percentage of CPU time during whic

Answer 1

As per the man page, the first line of results from iostat is an average from the moment the system was booted.

From my tests, this seems to apply also to the only line, if called e.g. as

iostat -x.

Try:

iostat -dmx 1 5

It will give you five lines with one second difference between lines. Discard the first, look at the others, perhaps like that the output will make more sense.