Re: [RFC] [PATCH 0/4] memcg: Kernel memory accounting.

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

On Fri, 14 Oct 2011 17:38:26 -0700
Suleiman Souhlal <ssouhlal@FreeBSD.org> wrote:

> This patch series introduces kernel memory accounting to memcg.
> It currently only accounts for slab.
> 
> With this, kernel memory gets counted in a memcg's usage_in_bytes.
> 
> Slab gets accounted per-page, by using per-cgroup kmem_caches that
> get created the first time an allocation of that type is done by
> that cgroup.
> This means that we only have to do charges/uncharges in the slow
> path of the slab allocator, which should have low performance
> impacts.
> 
> A per-cgroup kmem_cache will appear in slabinfo named like its
> original cache, with the cgroup's name in parenthesis.
> On cgroup deletion, the accounting gets moved to the root cgroup
> and any existing cgroup kmem_cache gets "dead" appended to its
> name, to indicate that its accounting was migrated.
> 
> TODO:
> 	- Per-memcg slab shrinking (we have patches for that already).
> 	- Make it support the other slab allocators.
> 	- Come up with a scheme that does not require holding
> 	  rcu_read_lock in the whole slab allocation path.
> 	- Account for other types of kernel memory than slab.
> 	- Migrate to the parent cgroup instead of root on cgroup
> 	  deletion.
> 

Could you show rough perforamance score ?

For example,
Assume cgroup dir as

  /cgroup/memory <--- root
		|-A  memory.use_hierarchy=1   no limit
		  |-B                         no limit
1) Compare kernel make 'sys time' under root, A, B.
2) run unixbench under root, A, B.

I think you may have some numbers already.

Thanks,
-Kame








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