Hi Ivana,
what do you think about this question ?
Thanks!
Weng Meiling
On 2013/8/14 14:37, Weng Meiling wrote:
> On 2013/8/14 11:32, Dhaval Giani wrote:
>> On Tue, Aug 13, 2013 at 10:07 PM, Weng Meiling
>> <wengmeiling.w...@huawei.com> wrote:
>>> On 2013/8/14 4:38, Dhaval Giani wrote:
>>>> Hi,
>>>>
>>>> On Tue, Aug 13, 2013 at 6:24 AM, Weng Meiling
>>>> <wengmeiling.w...@huawei.com> wrote:
>>>>>
>>>>> From: Weng Meiling <wengmeiling.w...@huawei.com>
>>>>>
>>>>> When setting the value of cgroup's control file by cgset -r, it's more
>>>>> appositely to yield an error when user try to set a read-only file or
>>>>> set a file not existed. So fix this by copying the dirty value in function
>>>>> cgroup_copy_controller_values().
>>>>>
>>>>
>>>> I am not sure I understand the issue. Do you have a failing case?
>>>>
>>> In fact, it's just a problem about user experience.
>>>
>>> Example:
>>>
>>> # lscgroup
>>> cpu:/
>>> cpu:/test
>>> cpuset:/
>>> cpuset:/test
>>>
>>> if user set the control value which is not existed:
>>>
>>> # cgset -r cpu.share=1000 test
>>> #
>>>
>>> or set a read-only control value:
>>>
>>> # cgset -r cpuset.memory_pressure=2 test
>>> #
>>>
>>> as we can see, there is nothing when user do these operations,
>>> is it better to yield an error to let user known what happen?:)
>>
>> So in its current form, I refuse to apply the patch.
>>
>> We dont know whether applying the value failed because it was
>> read-only, or because the name was wrong. This is just a hack, which
>> might hide other issues later on. I would much rather have a check
>> made (I am not sure where yet), which will confirm the file exists,
>> and if so, check whether it is read only.
>>
>> Thanks!
>> Dhaval
>>
>>
> Hi Dhaval,
>
> In fact, when setting the writable file for a invalidate value, there is
> also no any messages like this:
> # cgset -r cpu.shares=-1 test
> #
>
> Does the 'check' you said mean that checking whether the file exists or
> it is read only when setting the value, and then giving the apposite messages?
> If so, actually the libcg code has done all the check in function
> cg_set_control_value() , but the error is ignored in function
> cgroup_modify_cgroup（） like this:
>
> error = cg_set_control_value(path,
> cgroup->controller[i]->values[j]->value);
> free(path);
> path = NULL;
> /* don't consider error in files directly written by
> * the user as fatal */
> if (error && !cgroup->controller[i]->values[j]->dirty) {
> error = 0;
> continue;
> }
> if (error)
> goto err;
> cgroup->controller[i]->values[j]->dirty = false;
>
> because in function cgroup_copy_controller_values(), the dirty value is
> not copied, the dirty value always is zero, so the error is ignored. The
> patch adds the dirty value copy, actually the patch will change the result
> of 'cgset -r', before the patch when specifying multiple -r, just the
> validate
> value will be set, the wrong value is ignored. After the patch, if one of
> the values is wrong, the left values will not be set even if they are
> validate.
> I just think it's more friendly to let user know what happen.
>
> Thanks!
> Weng Meiling
>
>
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