NCQ enabled, 2 disks, 32 threads

heavy# zpool iostat 1
               capacity     operations    bandwidth
pool         used  avail   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
...
test        40.0G   888G     41      0  4.08M      0
test        40.0G   888G      0      0      0      0
test        40.0G   888G    220      0  25.3M      0
test        40.0G   888G    236      0  28.7M      0
test        40.0G   888G    249      0  31.1M      0
test        40.0G   888G    247      0  30.6M      0
test        40.0G   888G    244      0  30.4M      0
test        40.0G   888G    219      0  27.3M      0
test        40.0G   888G    223      0  27.9M      0
test        40.0G   888G    248      0  31.0M      0
test        40.0G   888G    252      0  31.6M      0
test        40.0G   888G    244      0  30.3M      0
test        40.0G   888G    225      0  28.2M      0
test        40.0G   888G    246      0  30.8M      0
test        40.0G   888G    222      0  27.6M      0
test        40.0G   888G    243      0  30.4M      0
test        40.0G   888G    225      0  28.2M      0
test        40.0G   888G    249      0  31.1M      0
test        40.0G   888G    244      0  30.6M      0
test        40.0G   888G    237      0  29.5M      0
test        40.0G   888G    247      0  30.9M      0
test        40.0G   888G    242      0  30.3M      0
test        40.0G   888G    251      0  31.4M      0
test        40.0G   888G    227      0  28.5M      0
test        40.0G   888G    222      0  27.8M      0
test        40.0G   888G    246      0  30.8M      0
test        40.0G   888G    237      0  29.7M      0
test        40.0G   888G    250      0  31.3M      0
test        40.0G   888G    237      0  29.6M      0
test        40.0G   888G    237      0  29.7M      0
test        40.0G   888G    230      0  28.8M      0
test        40.0G   888G    238      0  29.8M      0
test        40.0G   888G    229      0  28.7M      0
test        40.0G   888G    235      0  29.3M      0
test        40.0G   888G    250      0  31.3M      0
test        40.0G   888G    246      0  30.7M      0
test        40.0G   888G    248      0  31.1M      0
test        40.0G   888G    200      0  25.1M      0
test        40.0G   888G    229      0  28.7M      0
test        40.0G   888G    227      0  28.5M      0
test        40.0G   888G    222      0  27.8M      0
test        40.0G   888G    262      0  32.8M      0
test        40.0G   888G    247      0  30.9M      0
test        40.0G   888G    240      0  30.0M      0
test        40.0G   888G    223      0  28.0M      0
test        40.0G   888G    240      0  30.1M      0
test        40.0G   888G    238      0  29.8M      0
test        40.0G   888G    233      0  29.2M      0
test        40.0G   888G    233      0  29.2M      0
test        40.0G   888G    246      0  30.8M      0
test        40.0G   888G    277      0  34.7M      0
test        40.0G   888G    262      0  32.8M      0
test        40.0G   888G    274      0  34.3M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    289      0  36.1M      0
test        40.0G   888G    274      0  34.3M      0
test        40.0G   888G    279      0  34.9M      0
test        40.0G   888G    272      0  34.0M      0
test        40.0G   888G    267      0  33.4M      0
test        40.0G   888G    281      0  35.1M      0
test        40.0G   888G    282      0  35.3M      0
test        40.0G   888G    270      0  33.8M      0
test        40.0G   888G    269      0  33.6M      0
test        40.0G   888G    276      0  34.5M      0
test        40.0G   888G    275      0  34.4M      0
test        40.0G   888G    285      0  35.6M      0
test        40.0G   888G    267      0  33.4M      0
test        40.0G   888G    275      0  34.4M      0
test        40.0G   888G    273      0  34.2M      0
test        40.0G   888G    268      0  33.5M      0
test        40.0G   888G    283      0  35.4M      0
test        40.0G   888G    271      0  33.9M      0
test        40.0G   888G    269      0  33.7M      0
test        40.0G   888G    269      0  33.7M      0
test        40.0G   888G    291      0  36.4M      0
test        40.0G   888G    270      0  33.8M      0
test        40.0G   888G    281      0  35.2M      0
test        40.0G   888G    287      0  35.9M      0
test        40.0G   888G    278      0  34.7M      0
test        40.0G   888G    287      0  35.9M      0
test        40.0G   888G    280      0  35.0M      0
test        40.0G   888G    281      0  35.1M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    268      0  33.5M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    274      0  34.3M      0
test        40.0G   888G    253      0  31.7M      0
test        40.0G   888G    273      0  34.2M      0
test        40.0G   888G    279      0  34.9M      0
test        40.0G   888G    282      0  35.3M      0
test        40.0G   888G    264      0  33.0M      0
test        40.0G   888G    263      0  32.9M      0
test        40.0G   888G    261      0  32.7M      0
test        40.0G   888G    277      0  34.5M      0
test        40.0G   888G    285      0  35.6M      0
test        40.0G   888G    280      0  35.0M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    281      0  35.1M      0
test        40.0G   888G    280      0  35.0M      0
test        40.0G   888G    262      0  32.8M      0
test        40.0G   888G    281      0  35.1M      0
test        40.0G   888G    281      0  35.1M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    267      0  33.4M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    282      0  35.3M      0
test        40.0G   888G    280      0  35.0M      0
test        40.0G   888G    272      0  34.0M      0
test        40.0G   888G    266      0  33.3M      0
test        40.0G   888G    281      0  35.1M      0
test        40.0G   888G    279      0  34.9M      0
test        40.0G   888G    278      0  34.8M      0
test        40.0G   888G    265      0  33.2M      0
test        40.0G   888G    275      0  34.4M      0
test        40.0G   888G    268      0  33.5M      0
test        40.0G   888G    280      0  35.0M      0
test        40.0G   888G    277      0  34.7M      0
test        40.0G   888G    269      0  33.7M      0
test        40.0G   888G    250      0  31.3M      0
test        40.0G   888G    272      0  34.0M      0
test        40.0G   888G    279      0  34.9M      0
test        40.0G   888G    211      0  26.5M      0