Re: [PATCH -mm 1/5] quick lookup memcg by ID

From: Balbir Singh
Date: Mon Aug 02 2010 - 23:22:28 EST

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2010-08-02 19:13:04]:

> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Now, memory cgroup has an ID per cgroup and make use of it at
> - hierarchy walk,
> - swap recording.
> This patch is for making more use of it. The final purpose is
> to replace page_cgroup->mem_cgroup's pointer to an unsigned short.
> This patch caches a pointer of memcg in an array. By this, we
> don't have to call css_lookup() which requires radix-hash walk.
> This saves some amount of memory footprint at lookup memcg via id.

It is a memory versus speed tradeoff, but if the number of created
cgroups is low, it might not be all that slow, besides we do that for
swap_cgroup anyway - no?

Three Cheers,
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