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

KAMEZAWA Hiroyuki
2011-10-04T00:58:08Z

On Mon, 3 Oct 2011 14:18:38 +0400
Glauber Costa <glommer@parallels.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@parallels.com>
> CC: David S. Miller <davem@davemloft.net>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@jp.fujitsu.com>
> CC: Eric W. Biederman <ebiederm@xmission.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