NCQ disabled, 4 disks, 32 threads

heavy# zpool iostat 1
               capacity     operations    bandwidth
pool         used  avail   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
...
test        40.0G  1.77T    285      0  33.0M      0
test        40.0G  1.77T    460      0  57.1M      0
test        40.0G  1.77T    461      0  57.6M      0
test        40.0G  1.77T    471      0  58.9M      0
test        40.0G  1.77T    478      0  59.7M      0
test        40.0G  1.77T    458      0  57.0M      0
test        40.0G  1.77T    437      0  54.6M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    465      0  58.0M      0
test        40.0G  1.77T    471      0  58.9M      0
test        40.0G  1.77T    468      0  58.5M      0
test        40.0G  1.77T    467      0  58.4M      0
test        40.0G  1.77T    473      0  59.2M      0
test        40.0G  1.77T    467      0  58.4M      0
test        40.0G  1.77T    469      0  58.7M      0
test        40.0G  1.77T    482      0  60.3M      0
test        40.0G  1.77T    460      0  57.5M      0
test        40.0G  1.77T    466      0  58.3M      0
test        40.0G  1.77T    466      0  58.3M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    453      0  56.7M      0
test        40.0G  1.77T    462      0  57.7M      0
test        40.0G  1.77T    457      0  57.2M      0
test        40.0G  1.77T    457      0  57.2M      0
test        40.0G  1.77T    470      0  58.8M      0
test        40.0G  1.77T    476      0  59.5M      0
test        40.0G  1.77T    475      0  59.4M      0
test        40.0G  1.77T    428      0  53.6M      0
test        40.0G  1.77T    437      0  54.7M      0
test        40.0G  1.77T    444      0  55.6M      0
test        40.0G  1.77T    460      0  57.5M      0
test        40.0G  1.77T    448      0  56.1M      0
test        40.0G  1.77T    438      0  54.8M      0
test        40.0G  1.77T    439      0  55.0M      0
test        40.0G  1.77T    455      0  56.9M      0
test        40.0G  1.77T    455      0  56.9M      0
test        40.0G  1.77T    475      0  59.4M      0
test        40.0G  1.77T    474      0  59.3M      0
test        40.0G  1.77T    469      0  58.7M      0
test        40.0G  1.77T    448      0  56.1M      0
test        40.0G  1.77T    470      0  58.8M      0
test        40.0G  1.77T    458      0  57.3M      0
test        40.0G  1.77T    452      0  56.6M      0
test        40.0G  1.77T    458      0  57.3M      0
test        40.0G  1.77T    472      0  59.0M      0
test        40.0G  1.77T    458      0  57.3M      0
test        40.0G  1.77T    455      0  56.9M      0
test        40.0G  1.77T    467      0  58.4M      0
test        40.0G  1.77T    483      0  60.4M      0
test        40.0G  1.77T    462      0  57.8M      0
test        40.0G  1.77T    471      0  58.9M      0
test        40.0G  1.77T    480      0  60.0M      0
test        40.0G  1.77T    459      0  57.4M      0
test        40.0G  1.77T    453      0  56.7M      0
test        40.0G  1.77T    463      0  57.9M      0
test        40.0G  1.77T    466      0  58.3M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    470      0  58.8M      0
test        40.0G  1.77T    465      0  58.2M      0
test        40.0G  1.77T    446      0  55.8M      0
test        40.0G  1.77T    462      0  57.8M      0
test        40.0G  1.77T    450      0  56.3M      0
test        40.0G  1.77T    461      0  57.7M      0
test        40.0G  1.77T    459      0  57.4M      0
test        40.0G  1.77T    462      0  57.8M      0
test        40.0G  1.77T    465      0  58.2M      0
test        40.0G  1.77T    439      0  54.9M      0
test        40.0G  1.77T    433      0  54.2M      0
test        40.0G  1.77T    467      0  58.4M      0
test        40.0G  1.77T    465      0  58.2M      0
test        40.0G  1.77T    466      0  58.3M      0
test        40.0G  1.77T    445      0  55.7M      0
test        40.0G  1.77T    456      0  57.1M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    473      0  59.2M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    463      0  57.9M      0
test        40.0G  1.77T    453      0  56.6M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    459      0  57.4M      0
test        40.0G  1.77T    457      0  57.2M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    462      0  57.8M      0
test        40.0G  1.77T    460      0  57.5M      0
test        40.0G  1.77T    469      0  58.7M      0
test        40.0G  1.77T    457      0  57.2M      0
test        40.0G  1.77T    448      0  56.0M      0
test        40.0G  1.77T    484      0  60.5M      0
test        40.0G  1.77T    469      0  58.7M      0
test        40.0G  1.77T    456      0  57.1M      0
test        40.0G  1.77T    467      0  58.4M      0
test        40.0G  1.77T    463      0  57.9M      0
test        40.0G  1.77T    457      0  57.2M      0
test        40.0G  1.77T    460      0  57.5M      0
test        40.0G  1.77T    451      0  56.4M      0
test        40.0G  1.77T    453      0  56.7M      0
test        40.0G  1.77T    457      0  57.2M      0
test        40.0G  1.77T    465      0  58.2M      0
test        40.0G  1.77T    453      0  56.7M      0
test        40.0G  1.77T    456      0  57.1M      0
test        40.0G  1.77T    462      0  57.8M      0
test        40.0G  1.77T    462      0  57.8M      0
test        40.0G  1.77T    450      0  56.3M      0
test        40.0G  1.77T    465      0  58.2M      0
test        40.0G  1.77T    468      0  58.5M      0
test        40.0G  1.77T    450      0  56.3M      0
test        40.0G  1.77T    452      0  56.5M      0
test        40.0G  1.77T    452      0  56.6M      0
test        40.0G  1.77T    454      0  56.8M      0
test        40.0G  1.77T    460      0  57.5M      0
test        40.0G  1.77T    440      0  55.1M      0
test        40.0G  1.77T    460      0  57.5M      0
test        40.0G  1.77T    459      0  57.4M      0
test        40.0G  1.77T    469      0  58.7M      0
test        40.0G  1.77T    455      0  56.9M      0
test        40.0G  1.77T    452      0  56.6M      0
test        40.0G  1.77T    453      0  56.7M      0
test        40.0G  1.77T    451      0  56.4M      0
test        40.0G  1.77T    464      0  58.0M      0
test        40.0G  1.77T    457      0  57.2M      0