[Devel] Re: [ckrm-tech] [PATCH] BC: resource beancounters (v4) (added user memory)

[Pavel Emelianov]

Chandra Seetharaman wrote:
> On Mon, 2006-09-11 at 12:13 +0400, Pavel Emelianov wrote:
>
> <snip>
>   
>>> Don't start the new container or change the guarantees of the existing
>>> ones
>>> to accommodate this one :) The QoS design (done by the administrator)
>>> should
>>> take care of such use-cases. It would be perfectly ok to have a container
>>> that does not care about guarantees to set their guarantee to 0 and set
>>> their limit to the desired value. As Chandra has been stating we need two
>>> parameters (guarantee, limit), either can be optional, but not both.
>>>       
>> If I set up 9 groups to have 100Mb limit then I have 100Mb assured (on
>> 1Gb node)
>> for the 10th one exactly. And I do not have to set up any guarantee as
>> it won't affect
>> anything. So what a guarantee parameter is needed for?
>>     
>
> I do not think it is that simple since
>  - there is typically more than one class I want to set guarantee to
>  - I will not able to use both limit and guarantee
>  - Implementation will not be work-conserving.
>
> Also, How would you configure the following in your model ?
>
> 5 classes: Class A(10, 40), Class B(20, 100), Class C (30, 100), Class D
> (5, 100), Class E(15, 50); (class_name(guarantee, limit))
>   
What's the total memory amount on the node? Without it it's hard to make
any
guarantee.
> "Limit only" approach works for DoS prevention. But for providing QoS
> you would need guarantee.
>   
You may not provide guarantee on physycal resource for a particular group
without limiting its usage by other groups. That's my major idea.