Re: About cgroup memory limits

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

(2012/05/25 13:16), Zhu Yanhai wrote:
> 2012/5/10 KAMEZAWA Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com>:
>> (2012/05/10 3:37), Andre Nathan wrote:
>>
>>> Hello
>>>
>>> I'm doing some tests with LXC and how it interacts with the memory
>>> cgroup limits, more specifically the memory.limit_in_bytes control file.
>>>
>>> Am I correct in my understanding of the memory cgroup documentation[1]
>>> that the limit set in memory.limit_in_bytes is applied to the sum of the
>>> fields 'cache', 'rss' and 'mapped_file' in the memory.stat file?
>>>
>>
>> cache includes mapped_file. Then,
>
> Excuse me, but it does read:
>
> 	switch (ctype) {
> 	case MEM_CGROUP_CHARGE_TYPE_CACHE:
> 	case MEM_CGROUP_CHARGE_TYPE_SHMEM:
> 		SetPageCgroupCache(pc);
> 		SetPageCgroupUsed(pc);
> 		break;
> 	case MEM_CGROUP_CHARGE_TYPE_MAPPED:
> 		ClearPageCgroupCache(pc);
> 		SetPageCgroupUsed(pc);
> 		break;
> 	default:
> 		break;
> 	}
> 	mem_cgroup_charge_statistics(mem, pc, page_size);
>
> And then, in 	mem_cgroup_charge_statistics() we have :
>
> 	if (PageCgroupCache(pc))
> 		__mem_cgroup_stat_add_safe(cpustat,
> 			MEM_CGROUP_STAT_CACHE, numpages);
> 	else
> 		__mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS,
> 			numpages);
>
> So it seems that rss includes mapped_file, not cache?
>
Why you think so ? mapped_file is mapped file cache. All file caches
are accountned as STAT_CACHE.


TYPE_MAPPDED doesn't mean mapped_file.
In above, TYPE_MAPPED is called via anonymous page fault.
It represents anonymous page, counted as RSS.
I wonder it may be better to rename these macros.


Thanks,
-Kame