| Re: [PATCH v6 06/10] tcp buffer limitation: per-cgroup limit [message #44248 is a reply to message #44232] |
Mon, 28 November 2011 03:24   |
KAMEZAWA Hiroyuki
Messages: 463
Registered: September 2006
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Senior Member |
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some comments.
On Fri, 25 Nov 2011 15:38:12 -0200
Glauber Costa <glommer@parallels.com> wrote:
> This patch uses the "tcp.limit_in_bytes" field of the kmem_cgroup to
> effectively control the amount of kernel memory pinned by a cgroup.
>
> This value is ignored in the root cgroup, and in all others,
> caps the value specified by the admin in the net namespaces'
> view of tcp_sysctl_mem.
>
> If namespaces are being used, the admin is allowed to set a
> value bigger than cgroup's maximum, the same way it is allowed
> to set pretty much unlimited values in a real box.
>
> 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>
<snip>
> EXPORT_SYMBOL(tcp_destroy_cgroup);
> +
> +int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
> +{
> + struct net *net = current->nsproxy->net_ns;
> + struct tcp_memcontrol *tcp;
> + struct cg_proto *cg_proto;
> + int i;
> + int ret;
> +
> + cg_proto = tcp_prot.proto_cgroup(memcg);
> + if (!cg_proto)
> + return -EINVAL;
> +
> + tcp = tcp_from_cgproto(cg_proto);
> +
> + ret = res_counter_set_limit(&tcp->tcp_memory_allocated, val);
Here, you changed the limit.
> + if (ret)
> + return ret;
> +
> + val >>= PAGE_SHIFT;
Here, you modifies 'val'
> +
> + for (i = 0; i < 3; i++)
> + tcp->tcp_prot_mem[i] = min_t(long, val,
> + net->ipv4.sysctl_tcp_mem[i]);
> +
> + if (val == RESOURCE_MAX)
> + jump_label_dec(&memcg_socket_limit_enabled);
the 'val' never be RESOUECE_MAX.
> + else {
> + u64 old_lim;
> + old_lim = res_counter_read_u64(&tcp->tcp_memory_allocated,
> + RES_LIMIT);
old_lim is not already overwritten ?
> + if (old_lim == RESOURCE_MAX)
> + jump_label_inc(&memcg_socket_limit_enabled);
> + }
> + return 0;
> +}
> +
Thanks,
-Kame
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