On Wed, Aug 15, 2012 at 8:34 AM, Christoph Lameter <cl@linux.com> wrote:
> On Wed, 15 Aug 2012, Glauber Costa wrote:
>
>> On 08/15/2012 06:47 PM, Christoph Lameter wrote:
>> > On Wed, 15 Aug 2012, Michal Hocko wrote:
>> >
>> >>> That is not what the kernel does, in general. We assume that if he wants
>> >>> that memory and we can serve it, we should. Also, not all kernel memory
>> >>> is unreclaimable. We can shrink the slabs, for instance. Ying Han
>> >>> claims she has patches for that already...
>> >>
>> >> Are those patches somewhere around?
>> >
>> > You can already shrink the reclaimable slabs (dentries / inodes) via
>> > calls to the subsystem specific shrinkers. Did Ying Han do anything to
>> > go beyond that?
>> >
>> That is not enough for us.
>> We would like to make sure that the objects being discarded belong to
>> the memcg which is under pressure. We don't need to be perfect here, and
>> an occasional slip is totally fine. But if in general, shrinking from
>> memcg A will mostly wipe out objects from memcg B, we harmed the system
>> in return for nothing good.
>
> How can you figure out which objects belong to which memcg? The ownerships
> of dentries and inodes is a dubious concept already.
I figured it out based on the kernel slab accounting.
obj->page->kmem_cache->memcg
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