NCQ enabled, 16 disks, 32 threads

heavy# zpool iostat 1
               capacity     operations    bandwidth
pool         used  avail   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
...
test        40.0G  7.21T     41      0  4.15M      0
test        40.0G  7.21T      0      0      0      0
test        40.0G  7.21T  1.20K      0   152M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.66K      0   212M      0
test        40.0G  7.21T  1.67K      0   213M      0
test        40.0G  7.21T  1.63K      0   209M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.67K      0   214M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.62K      0   208M      0
test        40.0G  7.21T  1.66K      0   213M      0
test        40.0G  7.21T  1.67K      0   213M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.63K      0   208M      0
test        40.0G  7.21T  1.62K      0   208M      0
test        40.0G  7.21T  1.66K      0   212M      0
test        40.0G  7.21T  1.64K      0   210M      0
test        40.0G  7.21T  1.63K      0   209M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.63K      0   209M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.63K      0   209M      0
test        40.0G  7.21T  1.62K      0   208M      0
test        40.0G  7.21T  1.60K      0   204M      0
test        40.0G  7.21T  1.62K      0   208M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.61K      0   207M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.67K      0   213M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.63K      0   209M      0
test        40.0G  7.21T  1.55K      0   199M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.55K      0   198M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.64K      0   210M      0
test        40.0G  7.21T  1.63K      0   209M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.55K      0   199M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.53K      0   196M      0
test        40.0G  7.21T  1.59K      0   203M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.61K      0   207M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.59K      0   203M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.60K      0   205M      0
test        40.0G  7.21T  1.54K      0   198M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.59K      0   203M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.59K      0   203M      0
test        40.0G  7.21T  1.56K      0   199M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.53K      0   196M      0
test        40.0G  7.21T  1.62K      0   208M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.58K      0   203M      0
test        40.0G  7.21T  1.55K      0   199M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.58K      0   203M      0
test        40.0G  7.21T  1.56K      0   199M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.58K      0   203M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.56K      0   199M      0
test        40.0G  7.21T  1.60K      0   204M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.54K      0   197M      0
test        40.0G  7.21T  1.59K      0   203M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.58K      0   202M      0
test        40.0G  7.21T  1.61K      0   206M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.59K      0   204M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.55K      0   198M      0
test        40.0G  7.21T  1.53K      0   196M      0
test        40.0G  7.21T  1.56K      0   200M      0
test        40.0G  7.21T  1.54K      0   197M      0
test        40.0G  7.21T  1.62K      0   207M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.57K      0   201M      0
test        40.0G  7.21T  1.51K      0   193M      0
test        40.0G  7.21T  1.29K      0   165M      0