linux-kernel - Re: [PATCH v4 3/8] foundations of per-cgroup memory pressure controlling.

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Message-Id: <20111004095715.479da44d.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Tue, 4 Oct 2011 09:57:15 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Glauber Costa <glommer@...allels.com>
Cc:	linux-kernel@...r.kernel.org, paul@...lmenage.org,
	lizf@...fujitsu.com, ebiederm@...ssion.com, davem@...emloft.net,
	gthelen@...gle.com, netdev@...r.kernel.org, linux-mm@...ck.org,
	kirill@...temov.name, avagin@...allels.com
Subject: Re: [PATCH v4 3/8] foundations of per-cgroup memory pressure
 controlling.

On Mon,  3 Oct 2011 14:18:38 +0400
Glauber Costa <glommer@...allels.com> wrote:

> This patch converts struct sock fields memory_pressure,
> memory_allocated, sockets_allocated, and sysctl_mem (now prot_mem)
> to function pointers, receiving a struct mem_cgroup parameter.
> 
> enter_memory_pressure is kept the same, since all its callers
> have socket a context, and the kmem_cgroup can be derived from
> the socket itself.
> 
> To keep things working, the patch convert all users of those fields
> to use acessor functions.
> 
> In my benchmarks I didn't see a significant performance difference
> with this patch applied compared to a baseline (around 1 % diff, thus
> inside error margin).
> 
> Signed-off-by: Glauber Costa <glommer@...allels.com>
> CC: David S. Miller <davem@...emloft.net>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@...fujitsu.com>
> CC: Eric W. Biederman <ebiederm@...ssion.com>

A nitpick.

 
>  #ifdef CONFIG_INET
>  struct sock;
> +struct proto;
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>  void sock_update_memcg(struct sock *sk);
>  void sock_release_memcg(struct sock *sk);
> -
> +void memcg_sock_mem_alloc(struct mem_cgroup *mem, struct proto *prot,
> +			  int amt, int *parent_failure);
> +void memcg_sock_mem_free(struct mem_cgroup *mem, struct proto *prot, int amt);
> +void memcg_sockets_allocated_dec(struct mem_cgroup *mem, struct proto *prot);
> +void memcg_sockets_allocated_inc(struct mem_cgroup *mem, struct proto *prot);
>  #else
> +/* memcontrol includes sockets.h, that includes memcontrol.h ... */
> +static inline void memcg_sock_mem_alloc(struct mem_cgroup *mem,
> +					struct proto *prot, int amt,
> +					int *parent_failure)
> +{
> +}

In these days, at naming memory cgroup pointers, we use "memcg" instead of
"mem". So, could you use "memcg" for represeinting memory cgroup ?


> +
> +void memcg_sock_mem_alloc(struct mem_cgroup *mem, struct proto *prot,
> +			  int amt, int *parent_failure)
> +{
> +	mem = parent_mem_cgroup(mem);
> +	for (; mem != NULL; mem = parent_mem_cgroup(mem)) {
> +		long alloc;
> +		long *prot_mem = prot->prot_mem(mem);
> +		/*
> +		 * Large nestings are not the common case, and stopping in the
> +		 * middle would be complicated enough, that we bill it all the
> +		 * way through the root, and if needed, unbill everything later
> +		 */
> +		alloc = atomic_long_add_return(amt,
> +					       prot->memory_allocated(mem));
> +		*parent_failure |= (alloc > prot_mem[2]);
> +	}
> +}
> +EXPORT_SYMBOL(memcg_sock_mem_alloc);

Hmm. why not using res_counter ? for reusing 'unbill' code ?

Thanks,
-Kame

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