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

[Pavel Emelianov]

Balbir Singh wrote:
> Dave Hansen wrote:
>> On Fri, 2006-09-08 at 11:33 +0400, Pavel Emelianov wrote:
>>> I'm afraid we have different understandings of what a "guarantee" is.
>>
>> It appears so.
>>
>>> Don't we?
>>> Guarantee may be one of
>>>
>>>   1. container will be able to touch that number of pages
>>>   2. container will be able to sys_mmap() that number of pages
>>>   3. container will not be killed unless it touches that number of
>>> pages
>>
>> A "death sentence" guarantee?  I like it. :)
>>
>>>   4. anything else
>>>
>>> Let's decide what kind of a guarantee we want.
>
> I think of guarantees w.r.t resources as the lower limit on the resource.
> Guarantees and limits can be thought of as the range (guarantee, limit]
> for the usage of the resource.
>
>>
>> I think of it as: "I will be allowed to use this many total pages, and
>> they are guaranteed not to fail."  (1), I think.  The sum of all of the
>> system's guarantees must be less than or equal to the amount of free
>> memory on the machine. 
>
> Yes, totally agree.

Such a guarantee is really a limit and this limit is even harder than
BC's one :)

E.g. I have a node with 1Gb of ram and 10 containers with 100Mb
guarantee each.
I want to start one more. What shall I do not to break guarantees?

>
>> If we knew to which NUMA node the memory was going to go, we might as
>> well take the pages out of the allocator.
>>
>> -- Dave
>>