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Date: Sat, 24 Sep 2011 10:35:16 -0300
From: Glauber Costa <glommer@...allels.com>
To: Balbir Singh <bsingharora@...il.com>
CC: <linux-kernel@...r.kernel.org>, <paul@...lmenage.org>,
<lizf@...fujitsu.com>, <kamezawa.hiroyu@...fujitsu.com>,
<ebiederm@...ssion.com>, <davem@...emloft.net>,
<gthelen@...gle.com>, <netdev@...r.kernel.org>,
<linux-mm@...ck.org>, <kirill@...temov.name>
Subject: Re: [PATCH v3 6/7] tcp buffer limitation: per-cgroup limit
On 09/22/2011 08:08 PM, Balbir Singh wrote:
> On Mon, Sep 19, 2011 at 6:26 AM, Glauber Costa<glommer@...allels.com> wrote:
>> This patch uses the "tcp_max_mem" field of the kmem_cgroup to
>> effectively control the amount of kernel memory pinned by a cgroup.
>>
>> We have to make sure that none of the memory pressure thresholds
>> specified in the namespace are bigger than the current cgroup.
>>
>> 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>
>> ---
>> Documentation/cgroups/memory.txt | 1 +
>> include/linux/memcontrol.h | 10 ++++
>> mm/memcontrol.c | 89 +++++++++++++++++++++++++++++++++++---
>> net/ipv4/sysctl_net_ipv4.c | 20 ++++++++
>> 4 files changed, 113 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
>> index 6f1954a..1ffde3e 100644
>> --- a/Documentation/cgroups/memory.txt
>> +++ b/Documentation/cgroups/memory.txt
>> @@ -78,6 +78,7 @@ Brief summary of control files.
>>
>> memory.independent_kmem_limit # select whether or not kernel memory limits are
>> independent of user limits
>> + memory.kmem.tcp.max_memory # set/show hard limit for tcp buf memory
>>
>> 1. History
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 6b8c0c0..2df6db8 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -416,6 +416,9 @@ int tcp_init_cgroup_fill(struct proto *prot, struct cgroup *cgrp,
>> struct cgroup_subsys *ss);
>> void tcp_destroy_cgroup(struct proto *prot, struct cgroup *cgrp,
>> struct cgroup_subsys *ss);
>> +
>> +unsigned long tcp_max_memory(struct mem_cgroup *cg);
>> +void tcp_prot_mem(struct mem_cgroup *cg, long val, int idx);
>> #else
>> /* memcontrol includes sockets.h, that includes memcontrol.h ... */
>> static inline void memcg_sock_mem_alloc(struct mem_cgroup *mem,
>> @@ -441,6 +444,13 @@ static inline void sock_update_memcg(struct sock *sk)
>> static inline void sock_release_memcg(struct sock *sk)
>> {
>> }
>> +static inline unsigned long tcp_max_memory(struct mem_cgroup *cg)
>> +{
>> + return 0;
>> +}
>> +static inline void tcp_prot_mem(struct mem_cgroup *cg, long val, int idx)
>> +{
>> +}
>> #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
>> #endif /* CONFIG_INET */
>> #endif /* _LINUX_MEMCONTROL_H */
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 5e9b2c7..be5ab89 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -345,6 +345,7 @@ struct mem_cgroup {
>> spinlock_t pcp_counter_lock;
>>
>> /* per-cgroup tcp memory pressure knobs */
>> + int tcp_max_memory;
>
> Aren't we better of abstracting this in a different structure?
> Including all the tcp parameters in that abstraction and adding that
> structure here?
Humm, I think so, yes.
>> atomic_long_t tcp_memory_allocated;
>> struct percpu_counter tcp_sockets_allocated;
>> /* those two are read-mostly, leave them at the end */
>> @@ -352,6 +353,11 @@ struct mem_cgroup {
>> int tcp_memory_pressure;
>> };
>>
>> +static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
>> +{
>> + return (mem == root_mem_cgroup);
>> +}
>> +
>> static struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *mem);
>> /* Writing them here to avoid exposing memcg's inner layout */
>> #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> @@ -466,6 +472,56 @@ struct percpu_counter *sockets_allocated_tcp(struct mem_cgroup *sg)
>> return&sg->tcp_sockets_allocated;
>> }
>>
>> +static int tcp_write_maxmem(struct cgroup *cgrp, struct cftype *cft, u64 val)
>> +{
>> + struct mem_cgroup *sg = mem_cgroup_from_cont(cgrp);
>
> sg, I'd prefer memcg, does sg stand for socket group?
>
>> + struct mem_cgroup *parent = parent_mem_cgroup(sg);
>> + struct net *net = current->nsproxy->net_ns;
>> + int i;
>> +
>> + if (!cgroup_lock_live_group(cgrp))
>> + return -ENODEV;
>> +
>> + /*
>> + * We can't allow more memory than our parents. Since this
>> + * will be tested for all calls, by induction, there is no need
>> + * to test any parent other than our own
>> + * */
>> + if (parent&& (val> parent->tcp_max_memory))
>> + val = parent->tcp_max_memory;
>> +
>> + sg->tcp_max_memory = val;
>> +
>> + for (i = 0; i< 3; i++)
>> + sg->tcp_prot_mem[i] = min_t(long, val,
>> + net->ipv4.sysctl_tcp_mem[i]);
>> +
>> + cgroup_unlock();
>> +
>> + return 0;
>> +}
>> +
>> +static u64 tcp_read_maxmem(struct cgroup *cgrp, struct cftype *cft)
>> +{
>> + struct mem_cgroup *sg = mem_cgroup_from_cont(cgrp);
>
> sg? We generally use memcg as a convention
>
>> + u64 ret;
>> +
>> + if (!cgroup_lock_live_group(cgrp))
>> + return -ENODEV;
>> + ret = sg->tcp_max_memory;
>> +
>> + cgroup_unlock();
>> + return ret;
>> +}
>> +
>> +static struct cftype tcp_files[] = {
>> + {
>> + .name = "kmem.tcp.max_memory",
>> + .write_u64 = tcp_write_maxmem,
>> + .read_u64 = tcp_read_maxmem,
>> + },
>> +};
>> +
>> /*
>> * For ipv6, we only need to fill in the function pointers (can't initialize
>> * things twice). So keep it separated
>> @@ -487,8 +543,10 @@ int tcp_init_cgroup(struct proto *prot, struct cgroup *cgrp,
>> struct cgroup_subsys *ss)
>> {
>> struct mem_cgroup *cg = mem_cgroup_from_cont(cgrp);
>> + struct mem_cgroup *parent = parent_mem_cgroup(cg);
>> unsigned long limit;
>> struct net *net = current->nsproxy->net_ns;
>> + int ret = 0;
>>
>> cg->tcp_memory_pressure = 0;
>> atomic_long_set(&cg->tcp_memory_allocated, 0);
>> @@ -497,12 +555,25 @@ int tcp_init_cgroup(struct proto *prot, struct cgroup *cgrp,
>> limit = nr_free_buffer_pages() / 8;
>> limit = max(limit, 128UL);
>>
>> + if (parent)
>> + cg->tcp_max_memory = parent->tcp_max_memory;
>> + else
>> + cg->tcp_max_memory = limit * 2;
>> +
>> cg->tcp_prot_mem[0] = net->ipv4.sysctl_tcp_mem[0];
>> cg->tcp_prot_mem[1] = net->ipv4.sysctl_tcp_mem[1];
>> cg->tcp_prot_mem[2] = net->ipv4.sysctl_tcp_mem[2];
>>
>> tcp_init_cgroup_fill(prot, cgrp, ss);
>> - return 0;
>> + /*
>> + * For non-root cgroup, we need to set up all tcp-related variables,
>> + * but to be consistent with the rest of kmem management, we don't
>> + * expose any of the controls
>> + */
>> + if (!mem_cgroup_is_root(cg))
>> + ret = cgroup_add_files(cgrp, ss, tcp_files,
>> + ARRAY_SIZE(tcp_files));
>> + return ret;
>> }
>> EXPORT_SYMBOL(tcp_init_cgroup);
>>
>> @@ -514,6 +585,16 @@ void tcp_destroy_cgroup(struct proto *prot, struct cgroup *cgrp,
>> percpu_counter_destroy(&cg->tcp_sockets_allocated);
>> }
>> EXPORT_SYMBOL(tcp_destroy_cgroup);
>> +
>> +unsigned long tcp_max_memory(struct mem_cgroup *cg)
>> +{
>> + return cg->tcp_max_memory;
>> +}
>> +
>> +void tcp_prot_mem(struct mem_cgroup *cg, long val, int idx)
>> +{
>> + cg->tcp_prot_mem[idx] = val;
>> +}
>> #endif /* CONFIG_INET */
>> #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
>>
>> @@ -1092,12 +1173,6 @@ static struct mem_cgroup *mem_cgroup_get_next(struct mem_cgroup *iter,
>> #define for_each_mem_cgroup_all(iter) \
>> for_each_mem_cgroup_tree_cond(iter, NULL, true)
>>
>> -
>> -static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
>> -{
>> - return (mem == root_mem_cgroup);
>> -}
>> -
>> void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
>> {
>> struct mem_cgroup *mem;
>> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
>> index bbd67ab..cdc35f6 100644
>> --- a/net/ipv4/sysctl_net_ipv4.c
>> +++ b/net/ipv4/sysctl_net_ipv4.c
>> @@ -14,6 +14,7 @@
>> #include<linux/init.h>
>> #include<linux/slab.h>
>> #include<linux/nsproxy.h>
>> +#include<linux/memcontrol.h>
>> #include<linux/swap.h>
>> #include<net/snmp.h>
>> #include<net/icmp.h>
>> @@ -182,6 +183,10 @@ static int ipv4_tcp_mem(ctl_table *ctl, int write,
>> int ret;
>> unsigned long vec[3];
>> struct net *net = current->nsproxy->net_ns;
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> + int i;
>> + struct mem_cgroup *cg;
>> +#endif
>>
>> ctl_table tmp = {
>> .data =&vec,
>> @@ -198,6 +203,21 @@ static int ipv4_tcp_mem(ctl_table *ctl, int write,
>> if (ret)
>> return ret;
>>
>> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> + rcu_read_lock();
>> + cg = mem_cgroup_from_task(current);
>> + for (i = 0; i< 3; i++)
>> + if (vec[i]> tcp_max_memory(cg)) {
>> + rcu_read_unlock();
>> + return -EINVAL;
>> + }
>> +
>> + tcp_prot_mem(cg, vec[0], 0);
>> + tcp_prot_mem(cg, vec[1], 1);
>> + tcp_prot_mem(cg, vec[2], 2);
>> + rcu_read_unlock();
>> +#endif
>> +
>> net->ipv4.sysctl_tcp_mem[0] = vec[0];
>> net->ipv4.sysctl_tcp_mem[1] = vec[1];
>> net->ipv4.sysctl_tcp_mem[2] = vec[2];
>
> Balbir Singh
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