Re: [PATCH v2 2/5] memcg: provide root figures from system totals

[Kamezawa Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>]

(2013/03/06 19:52), Glauber Costa wrote:
> On 03/06/2013 02:45 PM, Kamezawa Hiroyuki wrote:
>> (2013/03/06 17:30), Glauber Costa wrote:
>>> On 03/06/2013 04:27 AM, Kamezawa Hiroyuki wrote:
>>>> (2013/03/05 22:10), Glauber Costa wrote:
>>>>> +	case _MEMSWAP: {
>>>>> +		struct sysinfo i;
>>>>> +		si_swapinfo(&i);
>>>>> +
>>>>> +		return ((memcg_read_root_rss() +
>>>>> +		atomic_long_read(&vm_stat[NR_FILE_PAGES])) << PAGE_SHIFT) +
>>>>> +		i.totalswap - i.freeswap;
>>>>
>>>> How swapcache is handled ? ...and How kmem works with this calc ?
>>>>
>>> I am ignoring kmem, because we don't account kmem for the root cgroup
>>> anyway.
>>>
>>> Setting the limit is invalid, and we don't account until the limit is
>>> set. Then it will be 0, always.
>>>
>>> For swapcache, I am hoping that totalswap - freeswap will cover
>>> everything swap related. If you think I am wrong, please enlighten me.
>>>
>>
>> i.totalswap - i.freeswap = # of used swap entries.
>>
>> SwapCache can be rss and used swap entry at the same time.
>>
> 
> Well, yes, but the rss entries would be accounted for in get_mm_rss(),
> won't they ?
> 
> What am I missing ?


I think the correct caluculation is

  Sum of all RSS + All file caches + (i.total_swap - i.freeswap - # of mapped SwapCache)


In the patch, mapped SwapCache is counted as both of rss and swap.

BTW, how about

  Sum of all LRU + (i.total_swap - i.freeswap - # of all SwapCache)
?

Thanks,
-Kame