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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: linux-mm@kvack.org, YAMAMOTO Takashi <yamamoto@valinux.co.jp>,
	Paul Menage <menage@google.com>,
	lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	David Rientjes <rientjes@google.com>,
	Pavel Emelianov <xemul@openvz.org>,
	Dhaval Giani <dhaval@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [mm] [PATCH 3/4] Memory cgroup hierarchical reclaim
Date: Sun, 2 Nov 2008 14:37:07 +0900	[thread overview]
Message-ID: <20081102143707.1bf7e2d0.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <20081101184849.2575.37734.sendpatchset@balbir-laptop>

On Sun, 02 Nov 2008 00:18:49 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> 
> This patch introduces hierarchical reclaim. When an ancestor goes over its
> limit, the charging routine points to the parent that is above its limit.
> The reclaim process then starts from the last scanned child of the ancestor
> and reclaims until the ancestor goes below its limit.
> 
> Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> ---
> 
>  mm/memcontrol.c |  153 +++++++++++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 129 insertions(+), 24 deletions(-)
> 
> diff -puN mm/memcontrol.c~memcg-hierarchical-reclaim mm/memcontrol.c
> --- linux-2.6.28-rc2/mm/memcontrol.c~memcg-hierarchical-reclaim	2008-11-02 00:14:59.000000000 +0530
> +++ linux-2.6.28-rc2-balbir/mm/memcontrol.c	2008-11-02 00:14:59.000000000 +0530
> @@ -132,6 +132,11 @@ struct mem_cgroup {
>  	 * statistics.
>  	 */
>  	struct mem_cgroup_stat stat;
> +	/*
> +	 * While reclaiming in a hiearchy, we cache the last child we
> +	 * reclaimed from.
> +	 */
> +	struct mem_cgroup *last_scanned_child;
>  };
>  static struct mem_cgroup init_mem_cgroup;
>  
> @@ -467,6 +472,125 @@ unsigned long mem_cgroup_isolate_pages(u
>  	return nr_taken;
>  }
>  
> +static struct mem_cgroup *
> +mem_cgroup_from_res_counter(struct res_counter *counter)
> +{
> +	return container_of(counter, struct mem_cgroup, res);
> +}
> +
> +/*
> + * Dance down the hierarchy if needed to reclaim memory. We remember the
> + * last child we reclaimed from, so that we don't end up penalizing
> + * one child extensively based on its position in the children list
> + */
> +static int
> +mem_cgroup_hierarchical_reclaim(struct mem_cgroup *mem, gfp_t gfp_mask)
> +{
> +	struct cgroup *cg, *cg_current, *cgroup;
> +	struct mem_cgroup *mem_child;
> +	int ret = 0;
> +
> +	if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
> +		return -ENOMEM;
> +
> +	/*
> +	 * try_to_free_mem_cgroup_pages() might not give us a full
> +	 * picture of reclaim. Some pages are reclaimed and might be
> +	 * moved to swap cache or just unmapped from the cgroup.
> +	 * Check the limit again to see if the reclaim reduced the
> +	 * current usage of the cgroup before giving up
> +	 */
> +	if (res_counter_check_under_limit(&mem->res))
> +		return 0;
> +
> +	/*
> +	 * Scan all children under the mem_cgroup mem
> +	 */
> +	if (!mem->last_scanned_child)
> +		cgroup = list_first_entry(&mem->css.cgroup->children,
> +				struct cgroup, sibling);
> +	else
> +		cgroup = mem->last_scanned_child->css.cgroup;
> +
> +	cg_current = cgroup;
> +
> +	/*
> +	 * We iterate twice, one of it is fundamental list issue, where
> +	 * the elements are inserted using list_add and hence the list
> +	 * behaves like a stack and list_for_entry_safe_from() stops
> +	 * after seeing the first child. The two loops help us work
> +	 * independently of the insertion and it helps us get a full pass at
> +	 * scanning all list entries for reclaim
> +	 */
> +	list_for_each_entry_safe_from(cgroup, cg, &cg_current->parent->children,
> +						 sibling) {
> +		mem_child = mem_cgroup_from_cont(cgroup);
> +
> +		/*
> +		 * Move beyond last scanned child
> +		 */
> +		if (mem_child == mem->last_scanned_child)
> +			continue;
> +
> +		ret = try_to_free_mem_cgroup_pages(mem_child, gfp_mask);
> +		mem->last_scanned_child = mem_child;
> +
> +		if (res_counter_check_under_limit(&mem->res)) {
> +			ret = 0;
> +			goto done;
> +		}
> +	}

Is this safe against cgroup create/remove ? cgroup_mutex is held ?

Thanks,
-Kame


  reply	other threads:[~2008-11-02  5:37 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-01 18:48 [mm][PATCH 0/4] Memory cgroup hierarchy introduction Balbir Singh
2008-11-01 18:48 ` [mm] [PATCH 1/4] Memory cgroup hierarchy documentation Balbir Singh
2008-11-04  6:25   ` Paul Menage
2008-11-04  6:26     ` Paul Menage
2008-11-05 13:55       ` Balbir Singh
2008-11-01 18:48 ` [mm] [PATCH 2/4] Memory cgroup resource counters for hierarchy Balbir Singh
2008-11-02  5:42   ` KAMEZAWA Hiroyuki
2008-11-02  5:49     ` Balbir Singh
2008-11-02  5:56       ` KAMEZAWA Hiroyuki
2008-11-02 11:46         ` Balbir Singh
2008-11-01 18:48 ` [mm] [PATCH 3/4] Memory cgroup hierarchical reclaim Balbir Singh
2008-11-02  5:37   ` KAMEZAWA Hiroyuki [this message]
2008-11-02  5:44     ` Balbir Singh
2008-11-04  2:17       ` KAMEZAWA Hiroyuki
2008-11-05 13:34         ` Balbir Singh
2008-11-05 16:20           ` KAMEZAWA Hiroyuki
2008-11-06 14:00             ` Balbir Singh
2008-11-01 18:49 ` [mm] [PATCH 4/4] Memory cgroup hierarchy feature selector Balbir Singh
2008-11-02  5:38   ` KAMEZAWA Hiroyuki
2008-11-02  6:03     ` Balbir Singh
2008-11-02  6:24       ` KAMEZAWA Hiroyuki
2008-11-02 15:52         ` Balbir Singh
2008-11-04  6:37           ` Paul Menage
2008-11-06  7:00             ` Balbir Singh
2008-11-06  7:01               ` Balbir Singh
2008-11-06  6:56         ` Balbir Singh
2008-11-06  7:30           ` KAMEZAWA Hiroyuki
2008-11-04  0:15 ` [mm][PATCH 0/4] Memory cgroup hierarchy introduction KAMEZAWA Hiroyuki
2008-11-05 13:51   ` Balbir Singh
2008-11-05 16:33     ` KAMEZAWA Hiroyuki
2008-11-05 17:52       ` Balbir Singh
2008-11-06  0:22         ` KAMEZAWA Hiroyuki
2008-11-04  9:21 ` [patch 1/2] memcg: hierarchy, yet another one KAMEZAWA Hiroyuki
2008-11-04  9:25 ` KAMEZAWA Hiroyuki

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