[Devel] Re: [PATCH] memory.swappiness

[Balbir Singh]

YAMAMOTO Takashi wrote:
> here's a trivial patch to implement memory.swappiness,
> which controls swappiness for cgroup memory reclamation.
> 
> it's against 2.6.24-rc3-mm2.
> 
> YAMAMOTO Takashi
> 
> 
> Signed-off-by: YAMAMOTO Takashi <yamamoto at valinux.co.jp>
> ---
> 
> --- linux-2.6.24-rc3-mm2-swappiness/include/linux/memcontrol.h.BACKUP	2007-12-03 11:49:27.176669111 +0900
> +++ linux-2.6.24-rc3-mm2-swappiness/include/linux/memcontrol.h	2007-12-03 10:00:29.049448425 +0900
> @@ -46,6 +46,7 @@ extern void mem_cgroup_out_of_memory(str
>  extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
>  					gfp_t gfp_mask);
>  int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);
> +extern int mem_cgroup_swappiness(struct mem_cgroup *mem);
> 
>  static inline struct mem_cgroup *mm_cgroup(const struct mm_struct *mm)
>  {
> --- linux-2.6.24-rc3-mm2-swappiness/mm/vmscan.c.BACKUP	2007-12-03 07:49:00.000000000 +0900
> +++ linux-2.6.24-rc3-mm2-swappiness/mm/vmscan.c	2007-12-03 10:01:57.559803379 +0900
> @@ -1030,7 +1030,7 @@ static int calc_reclaim_mapped(struct sc
>  	 *
>  	 * Max temporary value is vm_total_pages*100.
>  	 */
> -	imbalance *= (vm_swappiness + 1);
> +	imbalance *= (sc->swappiness + 1);
>  	imbalance /= 100;
> 
>  	/*
> @@ -1445,7 +1445,7 @@ unsigned long try_to_free_mem_cgroup_pag
>  		.may_writepage = !laptop_mode,
>  		.may_swap = 1,
>  		.swap_cluster_max = SWAP_CLUSTER_MAX,
> -		.swappiness = vm_swappiness,
> +		.swappiness = mem_cgroup_swappiness(mem_cont),
>  		.order = 0,
>  		.mem_cgroup = mem_cont,
>  		.isolate_pages = mem_cgroup_isolate_pages,
> --- linux-2.6.24-rc3-mm2-swappiness/mm/memcontrol.c.BACKUP	2007-12-03 07:49:00.000000000 +0900
> +++ linux-2.6.24-rc3-mm2-swappiness/mm/memcontrol.c	2007-12-03 11:22:40.157163781 +0900
> @@ -133,6 +133,7 @@ struct mem_cgroup {
> 
>  	unsigned long control_type;	/* control RSS or RSS+Pagecache */
>  	int	prev_priority;	/* for recording reclaim priority */
> +	unsigned int swappiness;	/* swappiness */
>  	/*
>  	 * statistics.
>  	 */
> @@ -1077,7 +1078,23 @@ static int mem_control_stat_open(struct 
>  	return single_open(file, mem_control_stat_show, cont);
>  }
> 
> +static int mem_cgroup_swappiness_write(struct cgroup *cont, struct cftype *cft,
> +				       u64 val)
> +{
> +	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
> +
> +	if (val > 100)
> +		return -EINVAL;
> +	mem->swappiness = val;
> +	return 0;
> +}
> +
> +static u64 mem_cgroup_swappiness_read(struct cgroup *cont, struct cftype *cft)
> +{
> +	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
> 
> +	return mem->swappiness;
> +}
> 
>  static struct cftype mem_cgroup_files[] = {
>  	{
> @@ -1110,8 +1127,21 @@ static struct cftype mem_cgroup_files[] 
>  		.name = "stat",
>  		.open = mem_control_stat_open,
>  	},
> +	{
> +		.name = "swappiness",
> +		.write_uint = mem_cgroup_swappiness_write,
> +		.read_uint = mem_cgroup_swappiness_read,
> +	},
>  };
> 
> +/* XXX probably it's better to move try_to_free_mem_cgroup_pages to
> +  memcontrol.c and kill this */
> +int mem_cgroup_swappiness(struct mem_cgroup *mem)
> +{
> +
> +	return mem->swappiness;
> +}
> +
>  static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
>  {
>  	struct mem_cgroup_per_node *pn;
> @@ -1155,6 +1185,8 @@ mem_cgroup_create(struct cgroup_subsys *
>  	res_counter_init(&mem->res);
> 
>  	mem->control_type = MEM_CGROUP_TYPE_ALL;
> +	mem->swappiness = 60; /* XXX probably should inherit a value from
> +				either parent cgroup or global vm_swappiness */

I prefer inheriting from the parent, but since our hierarchy support
needs work (changes to res_counter to support actual hierarchies), I
would prefer using global vm_swappiness.

>  	memset(&mem->info, 0, sizeof(mem->info));
> 
>  	for_each_node_state(node, N_POSSIBLE)

I like this patch very much

Acked-by: Balbir Singh <balbir at linux.vnet.ibm.com>

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