[Devel] Re: [PATCH] range-bw: Another I/O scheduling policy of dm-ioband supporting the predicable I/O bandwidth (range bandwidth)

[Dong-Jae Kang]

Hi Ryo

I am sorry for delayed reply.
I tested range-bw policy as you send me your configuration
and I found some logical bugs in range-bw including big scheduling overhead.

> I used fio 1.22. The below is a script which I actually ran.
>
>  #!/bin/sh
>  dev1=/dev/sdb4 # SATA disk
>  echo "0 $(sudo blockdev --getsize $dev1) ioband $dev1 share2 0 0
>    cgroup range-bw 0" | sudo dmsetup create ioband1
>
>  arg="--time_based --runtime=10 --ioengine=libaio --iodepth=50 \
>       --direct=1 --norandommap"
>
>  dmsetup message ioband1 0 attach 2
>  dmsetup message ioband1 0 attach 3
>  dmsetup message ioband1 0 min-bw 2:100
>  dmsetup message ioband1 0 max-bw 2:100
>  dmsetup message ioband1 0 min-bw 3:200
>  dmsetup message ioband1 0 max-bw 3:200

I recommend it is better to use different value in min-bw and max-bw
because its concept is to support range-bw with the minimum
guaranteeing and maximum limitation.
exampe - min-bw : 1024 / max-bw : 3072

>  echo $$ > /cgroup/grp1/tasks
>  fio $arg --rw=randread --name=grp1 --filename=/dev/mapper/ioband1 \
>          --output=r2-1.log &
>  echo $$ > /cgroup/grp2/tasks
>  fio $arg --rw=randread --name=grp2 --filename=/dev/mapper/ioband1 \
>          --output=r2-2.log &
>  wait
>
> Please feel free to ask me if you need more information.
>
>
> I'm look forward to seeing the results.
>
Thanks for your comments.
And I will fix the bugs and re-release it after several days
at that time, I inform you about that.

Ryo,
now, I am using bio-cgroup.....
but, Is there additional things I have to consider to support AIO or
dealyed I/O?

-- 
Best Regards,
Dong-Jae Kang
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