[Lxc-users] blkio.weight doesn't work

[Zhu Yanhai]

2011/12/14 Zhu Yanhai <zhu.yanhai at gmail.com>:
> 在 2011年12月14日 下午5:30，陈竞 <cj.magina at gmail.com> 写道：
>> i got the problem, my script is wrong, it should drop the cache, or it will
>> read data from cache,
>>  the script is :
>> sync
>> echo 3 > /proc/sys/vm/drop_caches
>> dd if=/tmp/file1 of=/dev/null
>>
>>
>> size of file1 is 400M, and i get new test result:
>> A: blkio.weight=100    cost 11.12s   speed is 37.5MB/s
>> B: blkio.weight=1000    cost 6.4s   speed is 65.7MB/s
>>
>> so the blkio.weight has some effect, bu the result is not as good as 1:10
>
> No, it is good.
> Blkio controller doesn't reserve bandwith for any groups, so what
> happened in your test is Group B finished before Group A, and after
> that Group A was able to occupy all bandwith, which made it much
> faster.
> So if the size of input files are the same, then the expect run time is:
> For Group B: Runtime A = size / 10B
> For Group A: Runtiem B = size / 10B + 0.9 * size / 11B

oops, a typo here, one couple of A and B are inverted, anyway the
point still stands.

-zyh

> Then Runtime A / Runtime B = 0.55
>
> In your test, 6.4 / 11.12 = 0.5755, so it works well.
>
> --
> Thanks,
> Zhu Yanhai
>
>
>>
>>
>> 2011/12/14 Zhu Yanhai <zhu.yanhai at gmail.com>
>>>
>>> And neither slice_idle nor group_idle is zero? Did you change any
>>> default parameters for CFQ?
>>>
>>> -zyh
>>>
>>> 在 2011年12月14日 下午4:55，陈竞 <cj.magina at gmail.com> 写道：
>>> > my io scheduler is CFQ.... So the result is weird
>>> >
>>> > 在 2011年12月14日 下午4:12，陈竞 <cj.magina at gmail.com>写道：
>>> >
>>> >> Hi， i'm using lxc in my project, i want to control disk io speed, so i
>>> >> use
>>> >> blkio.weight. I test it, but the result is confusing.
>>> >> I create two container A and B:
>>> >> A: blkio.weight = 100            B : blkio.weight=1000
>>> >>
>>> >> the running process in A and B are the same, which is bash script :
>>> >> dd if=/tmp/xxx of=/dev/null
>>> >> the size of xxx is 400Mb
>>> >>
>>> >> I suppose that A would be slower than B, since its weight is small,
>>> >> while
>>> >> the test turns out that B run as fast as A, they are in same speed.
>>> >> Can any help me figure it out ?
>>> >> PS: my kernel is 2.6.32, and lxc is 0.7.5
>>> >> --
>>> >> 陈竞，中科院计算技术研究所，高性能计算机中心
>>> >> Jing Chen HPCC.ICT.AC China
>>> >
>>> >
>>> >
>>> >
>>> > --
>>> > 陈竞，中科院计算技术研究所，高性能计算机中心
>>> > Jing Chen HPCC.ICT.AC China
>>> >
>>> >
>>> > ------------------------------------------------------------------------------
>>> > Cloud Computing - Latest Buzzword or a Glimpse of the Future?
>>> > This paper surveys cloud computing today: What are the benefits?
>>> > Why are businesses embracing it? What are its payoffs and pitfalls?
>>> > http://www.accelacomm.com/jaw/sdnl/114/51425149/
>>> > _______________________________________________
>>> > Lxc-users mailing list
>>> > Lxc-users at lists.sourceforge.net
>>> > https://lists.sourceforge.net/lists/listinfo/lxc-users
>>> >
>>
>>
>>
>>
>> --
>> 陈竞，中科院计算技术研究所，高性能计算机中心
>> Jing Chen HPCC.ICT.AC China