Re: [PATCH 1/9] io-throttle documentation

[Li Zefan]

KAMEZAWA Hiroyuki wrote:
> On Tue, 14 Apr 2009 22:21:12 +0200
> Andrea Righi <righi.andrea@xxxxxxxxx> wrote:
> 
>> +Example:
>> +* Create an association between an io-throttle group and a bio-cgroup group
>> +  with "bio" and "blockio" subsystems mounted in different mount points:
>> +  # mount -t cgroup -o bio bio-cgroup /mnt/bio-cgroup/
>> +  # cd /mnt/bio-cgroup/
>> +  # mkdir bio-grp
>> +  # cat bio-grp/bio.id
>> +  1
>> +  # mount -t cgroup -o blockio blockio /mnt/io-throttle
>> +  # cd /mnt/io-throttle
>> +  # mkdir foo
>> +  # echo 1 > foo/blockio.bio_id
> 
> Why do we need multiple cgroups at once to track I/O ?
> Seems complicated to me.
> 

IIUC, it also disallows other subsystems to be binded with blockio subsys:
  # mount -t cgroup -o blockio cpuset xxx /mnt
  (failed)

and if a task is moved from cg1(id=1) to cg2(id=2) in bio subsys, this task
will be moved from CG1(id=1) to CG2(id=2) automatically in blockio subsys.

All these are odd, unexpected, complex and bug-prone I think..

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