[Devel] Re: [PATCH 04/11] kmem slab accounting basic infrastructure

[David Rientjes]

On Mon, 25 Jun 2012, Glauber Costa wrote:

> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 9352d40..6f34b77 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -265,6 +265,10 @@ struct mem_cgroup {
>  	};
>  
>  	/*
> +	 * the counter to account for kernel memory usage.
> +	 */
> +	struct res_counter kmem;
> +	/*
>  	 * Per cgroup active and inactive list, similar to the
>  	 * per zone LRU lists.
>  	 */
> @@ -279,6 +283,7 @@ struct mem_cgroup {
>  	 * Should the accounting and control be hierarchical, per subtree?
>  	 */
>  	bool use_hierarchy;
> +	bool kmem_accounted;
>  
>  	bool		oom_lock;
>  	atomic_t	under_oom;
> @@ -391,6 +396,7 @@ enum res_type {
>  	_MEM,
>  	_MEMSWAP,
>  	_OOM_TYPE,
> +	_KMEM,
>  };
>  
>  #define MEMFILE_PRIVATE(x, val)	((x) << 16 | (val))
> @@ -1438,6 +1444,10 @@ done:
>  		res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
>  		res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
>  		res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
> +	printk(KERN_INFO "kmem: usage %llukB, limit %llukB, failcnt %llu\n",
> +		res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
> +		res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
> +		res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
>  }
>  
>  /*
> @@ -3879,6 +3889,11 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
>  		else
>  			val = res_counter_read_u64(&memcg->memsw, name);
>  		break;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +	case _KMEM:
> +		val = res_counter_read_u64(&memcg->kmem, name);
> +		break;
> +#endif

This shouldn't need an #ifdef, ->kmem is available on all 
CONFIG_CGROUP_MEM_RES_CTLR kernels.  Same with several of the other 
instances in this patch.

Can't these instances be addressed by not adding kmem_cgroup_files without 
CONFIG_CGROUP_MEM_RES_CTLR_KMEM?

>  	default:
>  		BUG();
>  	}
> @@ -3916,8 +3931,26 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
>  			break;
>  		if (type == _MEM)
>  			ret = mem_cgroup_resize_limit(memcg, val);
> -		else
> +		else if (type == _MEMSWAP)
>  			ret = mem_cgroup_resize_memsw_limit(memcg, val);
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +		else if (type == _KMEM) {
> +			ret = res_counter_set_limit(&memcg->kmem, val);
> +			if (ret)
> +				break;
> +			/*
> +			 * Once enabled, can't be disabled. We could in theory
> +			 * disable it if we haven't yet created any caches, or
> +			 * if we can shrink them all to death.
> +			 *
> +			 * But it is not worth the trouble
> +			 */
> +			if (!memcg->kmem_accounted && val != RESOURCE_MAX)
> +				memcg->kmem_accounted = true;
> +		}
> +#endif
> +		else
> +			return -EINVAL;
>  		break;
>  	case RES_SOFT_LIMIT:
>  		ret = res_counter_memparse_write_strategy(buffer, &val);
> @@ -3982,12 +4015,20 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
>  	case RES_MAX_USAGE:
>  		if (type == _MEM)
>  			res_counter_reset_max(&memcg->res);
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +		else if (type == _KMEM)
> +			res_counter_reset_max(&memcg->kmem);
> +#endif
>  		else
>  			res_counter_reset_max(&memcg->memsw);
>  		break;
>  	case RES_FAILCNT:
>  		if (type == _MEM)
>  			res_counter_reset_failcnt(&memcg->res);
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +		else if (type == _KMEM)
> +			res_counter_reset_failcnt(&memcg->kmem);
> +#endif
>  		else
>  			res_counter_reset_failcnt(&memcg->memsw);
>  		break;
> @@ -4549,6 +4590,33 @@ static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
>  }
>  
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +static struct cftype kmem_cgroup_files[] = {
> +	{
> +		.name = "kmem.limit_in_bytes",
> +		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
> +		.write_string = mem_cgroup_write,
> +		.read = mem_cgroup_read,
> +	},
> +	{
> +		.name = "kmem.usage_in_bytes",
> +		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
> +		.read = mem_cgroup_read,
> +	},
> +	{
> +		.name = "kmem.failcnt",
> +		.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
> +		.trigger = mem_cgroup_reset,
> +		.read = mem_cgroup_read,
> +	},
> +	{
> +		.name = "kmem.max_usage_in_bytes",
> +		.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
> +		.trigger = mem_cgroup_reset,
> +		.read = mem_cgroup_read,
> +	},
> +	{},
> +};
> +
>  static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
>  {
>  	return mem_cgroup_sockets_init(memcg, ss);
> @@ -4892,6 +4960,12 @@ mem_cgroup_create(struct cgroup *cont)
>  		int cpu;
>  		enable_swap_cgroup();
>  		parent = NULL;
> +
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +		WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys,
> +					   kmem_cgroup_files));
> +#endif
> +
>  		if (mem_cgroup_soft_limit_tree_init())
>  			goto free_out;
>  		root_mem_cgroup = memcg;
> @@ -4910,6 +4984,7 @@ mem_cgroup_create(struct cgroup *cont)
>  	if (parent && parent->use_hierarchy) {
>  		res_counter_init(&memcg->res, &parent->res);
>  		res_counter_init(&memcg->memsw, &parent->memsw);
> +		res_counter_init(&memcg->kmem, &parent->kmem);
>  		/*
>  		 * We increment refcnt of the parent to ensure that we can
>  		 * safely access it on res_counter_charge/uncharge.
> @@ -4920,6 +4995,7 @@ mem_cgroup_create(struct cgroup *cont)
>  	} else {
>  		res_counter_init(&memcg->res, NULL);
>  		res_counter_init(&memcg->memsw, NULL);
> +		res_counter_init(&memcg->kmem, NULL);
>  	}
>  	memcg->last_scanned_node = MAX_NUMNODES;
>  	INIT_LIST_HEAD(&memcg->oom_notify);