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

[Ryo Tsuruta]

Hi Dong-Jae, 

From: Dong-Jae Kang <baramsori72@xxxxxxxxx>
Subject: Re: [PATCH] range-bw: Another I/O scheduling policy of dm-ioband supporting the predicable I/O bandwidth (range bandwidth)
Date: Thu, 30 Apr 2009 14:15:24 +0900

> 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?

bio-cgroup is renamed to bklio-cgroup. :)
I don't clearly understand about range-bw but I think that you don't
need to consider to support them and it should be taken care of by
blkio-cgroup and the common part of dm-ioband, not the policy
implementation. Do you have any problems with AIO or delayed write?  

> 
> -- 
> Best Regards,
> Dong-Jae Kang
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