On Fri, Apr 20, 2012 at 2:57 PM, Glauber Costa <glommer@xxxxxxxxxxxxx> wrote:
> This patch adds the basic infrastructure for the accounting of the slab
> caches. To control that, the following files are created:
>
> * memory.kmem.usage_in_bytes
> * memory.kmem.limit_in_bytes
> * memory.kmem.failcnt
> * memory.kmem.max_usage_in_bytes
>
> They have the same meaning of their user memory counterparts. They reflect
> the state of the "kmem" res_counter.
>
> The code is not enabled until a limit is set. This can be tested by the flag
> "kmem_accounted". This means that after the patch is applied, no behavioral
> changes exists for whoever is still using memcg to control their memory usage.
>
> We always account to both user and kernel resource_counters. This effectively
> means that an independent kernel limit is in place when the limit is set
> to a lower value than the user memory. A equal or higher value means that the
> user limit will always hit first, meaning that kmem is effectively unlimited.
>
> People who want to track kernel memory but not limit it, can set this limit
> to a very high number (like RESOURCE_MAX - 1page - that no one will ever hit,
> or equal to the user memory)
>
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> CC: Michal Hocko <mhocko@xxxxxxx>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> CC: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---
> mm/memcontrol.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 79 insertions(+), 1 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 2810228..36f1e6b 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -252,6 +252,10 @@ struct mem_cgroup {
> };
>
> /*
> + * the counter to account for kernel memory usage.
> + */
> + struct res_counter kmem;
> + /*
> * Per cgroup active and inactive list, similar to the
> * per zone LRU lists.
> */
> @@ -266,6 +270,7 @@ struct mem_cgroup {
> * Should the accounting and control be hierarchical, per subtree?
> */
> bool use_hierarchy;
> + bool kmem_accounted;
>
> bool oom_lock;
> atomic_t under_oom;
> @@ -378,6 +383,7 @@ enum res_type {
> _MEM,
> _MEMSWAP,
> _OOM_TYPE,
> + _KMEM,
> };
>
> #define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
> @@ -1470,6 +1476,10 @@ done:
> res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
> res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
> res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
> + printk(KERN_INFO "kmem: usage %llukB, limit %llukB, failcnt %llu\n",
> + res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
> + res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
> + res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
> }
>
> /*
> @@ -3914,6 +3924,11 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
> else
> val = res_counter_read_u64(&memcg->memsw, name);
> break;
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + case _KMEM:
> + val = res_counter_read_u64(&memcg->kmem, name);
> + break;
> +#endif
> default:
> BUG();
> }
> @@ -3951,8 +3966,26 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
> break;
> if (type == _MEM)
> ret = mem_cgroup_resize_limit(memcg, val);
> - else
> + else if (type == _MEMSWAP)
> ret = mem_cgroup_resize_memsw_limit(memcg, val);
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> + else if (type == _KMEM) {
> + ret = res_counter_set_limit(&memcg->kmem, val);
> + if (ret)
> + break;
> + /*
> + * Once enabled, can't be disabled. We could in theory
> + * disable it if we haven't yet created any caches, or
> + * if we can shrink them all to death.
> + *
> + * But it is not worth the trouble
> + */
> + if (!memcg->kmem_accounted && val != RESOURCE_MAX)
> + memcg->kmem_accounted = true;
> + }
> +#endif
> + else
> + return -EINVAL;
> break;
> case RES_SOFT_LIMIT:
> ret = res_counter_memparse_write_strategy(buffer, &val);
Why is RESOURCE_MAX special?
-- Suleiman
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