Re: [RFC/PATCH] cgroup swap subsystem

[Pavel Emelyanov <xemul@openvz.org>]

KAMEZAWA Hiroyuki wrote:
> On Thu, 06 Mar 2008 11:20:17 +0300
> Pavel Emelyanov <xemul@openvz.org> wrote:
> 
>> KAMEZAWA Hiroyuki wrote:
>>> On Wed, 05 Mar 2008 17:14:12 +0300
>>> Pavel Emelyanov <xemul@openvz.org> wrote:
>>>>> Strongly agree.  Nobody's interested in swap as such: it's just
>>>>> secondary memory, where RAM is primary memory.  People want to
>>>>> control memory as the sum of the two; and I expect they may also
>>>>> want to control primary memory (all that the current memcg does)
>>>>> within that.  I wonder if such nesting of limits fits easily
>>>>> into cgroups or will be problematic.
>>>> This nesting would affect the res_couter abstraction, not the
>>>> cgroup infrastructure. Current design of resource counters doesn't
>>>> allow for such thing, but the extension is a couple-of-lines patch :)
>>>>
>>> IMHO, keeping res_counter simple is better.
>>>
>>> Is this kind of new entry in mem_cgroup not good ?
>>> ==
>>> struct mem_cgroup {
>>> 	...
>>> 	struct res_counter	memory_limit.
>>> 	struct res_counter	swap_limit.
>>> 	..
>>> }
>> I meant the same thing actually. By "nesting would affect" I
>> meant, that we might want to make res_counters hierarchical.
>>
>> That would kill two birds with one stone - we will make a true
>> hierarchical memory accounting and let charging of two counters
>> with one call.
> 
> Hierarchical res_counter makes sense.
> Making it in simple/reasonable style will be our challenge. 

I have this in my TODO list. Since this is not so urgent, then if you
don't mind I can prepare the patches next week - after I set the git 
tree up. This change doesn't seem that big.

> Thanks,
> -Kame
> 
> 

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