[Devel] [PATCH 2/7] tcp: Charge socket buffers into cg memory (v2)

[Vladimir Davydov]

On Wed, Jun 03, 2015 at 04:34:21PM +0300, Pavel Emelyanov wrote:
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 9dda309..d38868c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -498,7 +498,6 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
>  
>  /* Writing them here to avoid exposing memcg's inner layout */
>  #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
> -
>  void sock_update_memcg(struct sock *sk)
>  {
>  	if (mem_cgroup_sockets_enabled) {
> @@ -3039,11 +3038,33 @@ int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
>  	return ret;
>  }
>  
> -void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)

I've changed this code recently, so this patch does not apply. Please
update.

> +void memcg_charge_kmem_nofail(struct mem_cgroup *memcg, u64 size)
>  {
> +	struct res_counter *fail_res;
> +
> +	/*
> +	 * FIXME -- strictly speaking, this value should _also_
> +	 * be charged into kmem counter. But since res_counter_charge
> +	 * is sub-optimal (takes locks) AND we do not care much
> +	 * about kmem limits (at least for now) we can just directly
> +	 * charge into mem counter.
> +	 */

Please charge kmem too. As I've already told you it should not make any
difference in terms of performance, because we already have a bottleneck
of the same bandwidth.

Anyway, if we see any performance degradation, I will convert
mem_cgroup->kmem to a percpu counter.

> +	res_counter_charge_nofail(&memcg->res, size, &fail_res);
> +	if (do_swap_account)
> +		res_counter_uncharge(&memcg->memsw, size);
> +}
> +
> +void __memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
> +{
> +	/* FIXME -- uncharge also in kmem counter */

Please use memcg_uncharge_kmem instead of introducing this new function
with its ridiculous divergence between its name and actual doings.

>  	res_counter_uncharge(&memcg->res, size);
>  	if (do_swap_account)
>  		res_counter_uncharge(&memcg->memsw, size);
> +}
> +
> +void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
> +{
> +	__memcg_uncharge_kmem(memcg, size);
>  
>  	/* Not down to 0 */
>  	if (res_counter_uncharge(&memcg->kmem, size))