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

%util means how much time spent writing/reading per unit of time, you can compute it from the mean service time:

svctm  * (  r/s + w/s )  /1000 
= 0.66 *(0.24 + 0.57) /1000
= 0.0005346 

hence 0.05%

I haven't read your code, but obviously at less than 1 read or write per second it isn't loading the disks that much!