Cgroup: iops throttle problem

[张真]

Hello
My name is Zhen Zhang , me and Jiale Li recently test and analyze the cgroup
blkio functions.
We tested the buffered read a file using bio when the 
blkio.throttle.read_iops_device is set 1000.
The fio result file displays the iops is 13720 larger than 1000 when blocksize 
is 4K in fio.

We set different blocksize in fio:
4K, 8K , 16K, 32K, 64K, 128K, 256K, 512K, 1024K

The iops in fio:
13035, 7258, 3711, 1698, 907, 460, 228, 102, 54
When bs is less than 64K, the iops is larger than 1000, when bs is larger than
64K, the iops is less than 1000.
We tested it on ubuntu 16.04 with kernel 4.4.0

Dose this a problem of blkio iops throttle?