Re: [ckrm-tech] [RFC] [PATCH 00/12] CKRM after a major overhaul

[Kirill Korotaev <dev@openvz.org>]

>>>>Yes, it is effective, and the reclamation is O(1) too. It has couple of
>>>>problems by design, (1) doesn't handle shared pages and (2) doesn't
>>>>provide support for both min_shares and max_shares.
>>>
>>>Right.  I wanted to show proof-of-cencept of the pzone based controller
>>>and implemented minimal features necessary as the memory controller.
>>>So, the pzone based controller still needs development and some cleanup.
>>
>>Just out of curiosity, how it was meassured that it is effective?
> 
> 
> I don't have any benchmark numbers yet, so I can't explain the
> effectiveness with numbers.  I've been looking for the way to
> measure the cost of pzones correctly, but I've not found it out yet.
> 
> 
>>How does it work when there is a global memory shortage in the system?
> 
> 
> I guess you are referring to the situation that global memory is running
> out but there are free pages in pzones.  These free pages in pzones are
> handled as reserved for pzone users and not used even in global memory 
> shortage.
ok. Let me explain what I mean.
Imagine the situation with global memory shortage. In kernel, there are 
threads which do some job behalf the user, e.g. kjournald, loop etc. If 
the user has some pzone memory, but these threads fail to do their job 
some nasty things can happen (ext3 problems, deadlocks, OOM etc.)
If such behaviour is ok for you, then great. But did you consider it?

Also, I can't understand how it works with OOM killer. If pzones has 
enough memory, but there is a global shortage, who will be killed?

Thanks,
Kirill