Re: [RFC][PATCH 0/3] memcg: remove refcnt

[Balbir Singh <balbir@linux.vnet.ibm.com>]

KAMEZAWA Hiroyuki wrote:
> This patch is based on 2.6.25-rc8-mm1 + mem_cgroup_per_zone() fix.
> (already in -mm) 
> 
> This patch is a set for removing refcnt from memory resource controller's
> page_cgroup. Instead of ref_cnt, this patch uses page_mapped().
> By this, we can avoid unnecesary locks and calls to some extent.
> 
> Brief Patch Desc.
>  [1/3] change migration handling .... charge new-page before migration.
>  [2/3] remove refcnt             .... remove refcnt from page_cgroup.
>  [3/3] handle swapcache          .... handle swapcache again.
> 
> [1/3] works for better page migration handling.
> [2/3] works for better speed. (depends on [1/3])
> [3/3] works for swap-cache.   (depends on [2/3])
> 
> 
> 
> Unix bench execl result(ia64):
> No controller   :           43.0     2654.7      617.4
> with controller :           43.0     2461.3      572.4
> after this patch:           43.0     2553.6      593.9
> 
> If page_cgroup->ref_cnt is necessary (for some purpose), please tell me.
> 
> Plan:
> I'd like to push this set before complicated radix-tree page_cgroup set.
> But this should be reviewd before going ahead.
> 

I think this makes a lot of sense. We can push the optimizations independent of
the radix tree, so that it is easy to debug and develop.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

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