On 10/01/2012 04:25 PM, Michal Hocko wrote:
> On Tue 18-09-12 18:04:07, Glauber Costa wrote:
> [...]
>> include/linux/memcontrol.h | 4 +++-
>> mm/memcontrol.c | 26 ++++++++++++++++++++++++--
>> 2 files changed, 27 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 82ede9a..4ec9fd5 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -22,6 +22,7 @@
>> #include <linux/cgroup.h>
>> #include <linux/vm_event_item.h>
>> #include <linux/hardirq.h>
>> +#include <linux/jump_label.h>
>>
>> struct mem_cgroup;
>> struct page_cgroup;
>> @@ -401,9 +402,10 @@ struct sock;
>> void sock_update_memcg(struct sock *sk);
>> void sock_release_memcg(struct sock *sk);
>>
>> +extern struct static_key memcg_kmem_enabled_key;
>> static inline bool memcg_kmem_enabled(void)
>> {
>> - return true;
>> + return static_key_false(&memcg_kmem_enabled_key);
>> }
>>
>> extern bool __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg,
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 720e4bb..aada601 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -467,6 +467,8 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
>> #include <net/sock.h>
>> #include <net/ip.h>
>>
>> +struct static_key memcg_kmem_enabled_key;
>> +
>> static bool mem_cgroup_is_root(struct mem_cgroup *memcg);
>> static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size);
>> static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size);
>> @@ -624,6 +626,16 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
>> WARN_ON(mem_cgroup_is_root(memcg));
>> memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
>> }
>> +
>> +static void disarm_kmem_keys(struct mem_cgroup *memcg)
>> +{
>> + if (memcg_kmem_is_accounted(memcg))
>> + static_key_slow_dec(&memcg_kmem_enabled_key);
>> +}
>> +#else
>> +static void disarm_kmem_keys(struct mem_cgroup *memcg)
>> +{
>> +}
>> #endif /* CONFIG_MEMCG_KMEM */
>>
>> #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
>> @@ -639,6 +651,12 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
>> }
>> #endif
>>
>> +static void disarm_static_keys(struct mem_cgroup *memcg)
>> +{
>> + disarm_sock_keys(memcg);
>> + disarm_kmem_keys(memcg);
>> +}
>> +
>> static void drain_all_stock_async(struct mem_cgroup *memcg);
>>
>> static struct mem_cgroup_per_zone *
>> @@ -4131,7 +4149,11 @@ static void memcg_update_kmem_limit(struct mem_cgroup *memcg, u64 val)
>> */
>> mutex_lock(&set_limit_mutex);
>> if ((val != RESOURCE_MAX) && memcg_kmem_set_active(memcg)) {
>> -
>> + /*
>> + * Once the static branch is enabled it will only be
>> + * disabled when the last reference to memcg is gone.
>> + */
>> + static_key_slow_inc(&memcg_kmem_enabled_key);
>
> I guess the reason why we do not need to inc also for children is that
> we do not inherit kmem_accounted, right?
>
Yes, but I of course changed that in the upcoming version of the patch.
We now inherit the value everytime, and the static branches are updated
accordingly.
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