[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.

Sorry for late reply.

2009/5/12 Ryo Tsuruta <ryov at valinux.co.jp>:
> Hi Dong-Jae,
>> >> after bug-fix,I evaluated range-bw according to your configuration and
>> >> test environment
>> >> the result is in new relesed range-bw mail, [PATCH 0/2]
>> >> and more detailed documentation is also available and it can be
>> >> referred in [PATCH 1/2]
>> >>
>> >> Ryo,
>> >> can you check the result ?
>
> I did the same test as before and got the results as expected.
>
>               cgroup1    cgroup2
>  min:max-bw    0:100      0:200
>  -------------------------------------
>  read          100         197
>  write         103         198 [KB/s]
>

I think upper result is reasonable.
because you configured min and  max bandwidth as 0K:100K(for cgroup1)
and 0K:200K(for cgroup2).
So, range-bw supported appropriate and expected bandwidth with 1~3% error range.
minimum bandwidth was satisfied (0K, 0K ) and maximum bandwidth was
limited (100K, 200K)
but there is some considered point in use of range-bw as I described
in [PATCH 0/2] as below.

* Attention
-----------------
Range-BW supports the predicable I/O bandwidth, but it should be
configured in the scope of total I/O bandwidth of the I/O system to
guarantee the minimum I/O requirement. For example, if total I/O
bandwidth is 40Mbytes/sec, the summary of I/O bandwidth configured in
each process group should be equal or smaller than 40Mbytes/sec.
So, we need to check total I/O bandwidth before set it up.

If you need more another information about range-bw, reply to me.

> I got errors while applying your patch, some lines are wrapped with
> carriage returns.
>
>    +extern int policy_range_bw_init(struct ioband_device *dp, int argc,
>  >> char **argv);

Thank you for bug reporting
I will check it again.

>
> Thanks,
> Ryo Tsuruta
>



-- 
Best Regards,
Dong-Jae Kang
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