linux-kernel - Re: [PATCH][Cleanup] memcg: consolidates memory cgroup lru stat functions

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Date:	Thu, 7 Jul 2011 14:05:19 +0530
From:	Balbir Singh <bsingharora@...il.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
	Michal Hocko <mhocko@...e.cz>, Ying Han <yinghan@...gle.com>
Subject: Re: [PATCH][Cleanup] memcg: consolidates memory cgroup lru stat functions

On Thu, Jul 7, 2011 at 12:22 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@...fujitsu.com> wrote:
>
> In mm/memcontrol.c, there are many lru stat functions as..
>
> mem_cgroup_zone_nr_lru_pages
> mem_cgroup_node_nr_file_lru_pages
> mem_cgroup_nr_file_lru_pages
> mem_cgroup_node_nr_anon_lru_pages
> mem_cgroup_nr_anon_lru_pages
> mem_cgroup_node_nr_unevictable_lru_pages
> mem_cgroup_nr_unevictable_lru_pages
> mem_cgroup_node_nr_lru_pages
> mem_cgroup_nr_lru_pages
> mem_cgroup_get_local_zonestat
>
> Some of them are under #ifdef MAX_NUMNODES >1 and others are not.
> This seems bad. This patch consolidates all functions into
>
> mem_cgroup_zone_nr_lru_pages()
> mem_cgroup_node_nr_lru_pages()
> mem_cgroup_nr_lru_pages()
>
> For these functions, "which LRU?" information is passed by a mask.
>
> example)
> mem_cgroup_nr_lru_pages(mem, BIT(LRU_ACTIVE_ANON))
>
> And I added some macro as ALL_LRU, ALL_LRU_FILE, ALL_LRU_ANON.
> example)
> mem_cgroup_nr_lru_pages(mem, ALL_LRU)
>
> BTW, considering layout of NUMA memory placement of counters, this patch seems
> to be better.
>
> Now, when we gather all LRU information, we scan in following orer
>    for_each_lru -> for_each_node -> for_each_zone.
>
> This means we'll touch cache lines in different node in turn.
>
> After patch, we'll scan
>    for_each_node -> for_each_zone -> for_each_lru(mask)
>
> Then, we'll gather information in the same cacheline at once.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Looks like a good cleanup, but unfortunately I won't be able to test
any patches till the end of next week or so

Balbir Singh
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