I think this parameter will be usefull when the storage using RAID stripe , otherwise turn up this parameter is meaningless when only has one device。

发自网易邮箱大师

On 2/1/2018 04:29，Vitaliy Garnashevich<vgarnashevich@gmail.com> wrote：

I've done some more tests. Here they are all:

io1, 100 GB SSD, 1000 IOPS
effective_io_concurrency=0 Execution time: 40333.626 ms
effective_io_concurrency=1 Execution time: 163840.500 ms
effective_io_concurrency=2 Execution time: 162606.330 ms
effective_io_concurrency=4 Execution time: 163670.405 ms
effective_io_concurrency=8 Execution time: 161800.478 ms
effective_io_concurrency=16 Execution time: 161962.319 ms
effective_io_concurrency=32 Execution time: 160451.435 ms
effective_io_concurrency=64 Execution time: 161763.632 ms
effective_io_concurrency=128 Execution time: 161687.398 ms
effective_io_concurrency=256 Execution time: 160945.066 ms
effective_io_concurrency=256 Execution time: 161226.440 ms
effective_io_concurrency=128 Execution time: 161977.954 ms
effective_io_concurrency=64 Execution time: 159122.006 ms
effective_io_concurrency=32 Execution time: 154923.569 ms
effective_io_concurrency=16 Execution time: 160922.819 ms
effective_io_concurrency=8 Execution time: 160577.122 ms
effective_io_concurrency=4 Execution time: 157509.481 ms
effective_io_concurrency=2 Execution time: 161806.713 ms
effective_io_concurrency=1 Execution time: 164026.708 ms
effective_io_concurrency=0 Execution time: 40196.182 ms

gp2, 100 GB SSD
effective_io_concurrency=0 Execution time: 40262.781 ms
effective_io_concurrency=1 Execution time: 98125.987 ms
effective_io_concurrency=2 Execution time: 55343.776 ms
effective_io_concurrency=4 Execution time: 52505.638 ms
effective_io_concurrency=8 Execution time: 54954.024 ms
effective_io_concurrency=16 Execution time: 54346.455 ms
effective_io_concurrency=32 Execution time: 55196.626 ms
effective_io_concurrency=64 Execution time: 55057.956 ms
effective_io_concurrency=128 Execution time: 54963.510 ms
effective_io_concurrency=256 Execution time: 54339.258 ms

io1, 1 TB SSD, 3000 IOPS
effective_io_concurrency=0 Execution time: 40691.396 ms
effective_io_concurrency=1 Execution time: 87524.939 ms
effective_io_concurrency=2 Execution time: 54197.982 ms
effective_io_concurrency=4 Execution time: 55082.740 ms
effective_io_concurrency=8 Execution time: 54838.161 ms
effective_io_concurrency=16 Execution time: 52561.553 ms
effective_io_concurrency=32 Execution time: 54266.847 ms
effective_io_concurrency=64 Execution time: 54683.102 ms
effective_io_concurrency=128 Execution time: 54643.874 ms
effective_io_concurrency=256 Execution time: 42944.938 ms

gp2, 1 TB SSD
effective_io_concurrency=0 Execution time: 40072.880 ms
effective_io_concurrency=1 Execution time: 83528.679 ms
effective_io_concurrency=2 Execution time: 55706.941 ms
effective_io_concurrency=4 Execution time: 55664.646 ms
effective_io_concurrency=8 Execution time: 54699.658 ms
effective_io_concurrency=16 Execution time: 54632.291 ms
effective_io_concurrency=32 Execution time: 54793.305 ms
effective_io_concurrency=64 Execution time: 55227.875 ms
effective_io_concurrency=128 Execution time: 54638.744 ms
effective_io_concurrency=256 Execution time: 54869.761 ms

st1, 500 GB HDD
effective_io_concurrency=0 Execution time: 40542.583 ms
effective_io_concurrency=1 Execution time: 119996.892 ms
effective_io_concurrency=2 Execution time: 51137.998 ms
effective_io_concurrency=4 Execution time: 42301.922 ms
effective_io_concurrency=8 Execution time: 42081.877 ms
effective_io_concurrency=16 Execution time: 42253.782 ms
effective_io_concurrency=32 Execution time: 42087.216 ms
effective_io_concurrency=64 Execution time: 42112.105 ms
effective_io_concurrency=128 Execution time: 42271.850 ms
effective_io_concurrency=256 Execution time: 42213.074 ms

Regards,
Vitaliy