Re: [RFC][PATCH 4/14] delay page_cgroup freeing

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

KAMEZAWA Hiroyuki wrote:
> On Tue, 26 Aug 2008 17:16:20 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> 
>>> +/*
>>> + * per-cpu slot for freeing page_cgroup in lazy manner.
>>> + * All page_cgroup linked to this list is OBSOLETE.
>>> + */
>>> +struct mem_cgroup_sink_list {
>>> +	int count;
>>> +	struct page_cgroup *next;
>>> +};
>> Can't we reuse the lru field in page_cgroup to build a list? Do we need them on
>> the memory controller LRU if they are obsolete? I want to do something similar
>> for both additions and deletions - reuse pagevec style, basically. I am OK,
>> having a list as well, in that case we can just reuse the LRU pointer.
>>
> reusing page_cgroup->lru is not a choice because this patch is for avoid
> locking on mz->lru_lock (and kfree).
> But using vector can be a choice. I'll try in the next version.

Kame,

Do we need to use the lru_lock? If we do an atomic check on PcgObsolete(), can't
we use another lock for obsolete pages and still use the lru list head?

-- 
	Balbir

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