Re: [PATCH] Provide an interface to limit total page cache.

[Balbir Singh <balbir@in.ibm.com>]

Roy Huang wrote:
> Hi Balbir,
> 
> Thanks for your comment.
> 
> On 1/15/07, Balbir Singh <balbir@in.ibm.com> wrote:
> 
>> wakeup_kswapd and shrink_all_memory use swappiness to determine what to reclaim
>> (mapped pages or page cache).  This patch does not ensure that only
>> page cache is
>> reclaimed/limited. If the swappiness value is high, mapped pages will be hit.
>>
> You are right, it is possible to release mapped pages. It can be
> avoided by add a field in "struct scan_control" to determine whether
> mapped pages will be released.
> 

Yes that could be done. I have been trying to figure out if there is a good
reason why the LRU is common for both mapped and pagecache. Does it make
sense to split them up? I am still digging through lkml archives to see
if I can find something.

>> One could get similar functionality by implementing resource management.
>>
>> Resource  management splits tasks into groups and does management of
>> resources for the
>> groups rather than the whole system. Such a facility will come with a
>> resource controller for
>> memory (split into finer grain rss/page cache/mlock'ed memory, etc),
>> one for cpu, etc.
> I s there any more information in detail about resource controller?
> Even there is a resource controller for tasks, all memory is also
> possbile to be eaten up by page cache.


Yes, please see the discussions on lkml on resource management, ckrm,
beancounters and containers.

http://lwn.net/Articles/206697/ RFC for memory controller, might be a good
starting point

-- 

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs
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