[Devel] [PATCH rh7 1/3] memcg: add function to get container's ram size

[Konstantin Khorenko]

Kirill, please review the patch set.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team

On 05/21/2015 06:27 PM, Vladimir Davydov wrote:
> Sometimes we need to get the ram size of the container the current
> process belongs to and we cannot open the memory cgroup by name as we
> usually do (e.g. see ub_dirty_limits). This patch adds a function for
> this purpose, mem_cgroup_ram_pages.
> 
> In this function we implicitly assume that each container lives in its
> own top level memory cgroup. If it is changed (e.g. we move all
> containers to /machine.slice), then we must rework this function (as
> well as all the code in beancounters that gets stats from memcg). One
> way to do that is allow the userspace assign a memory cgroup to a ve or
> beancounter cgroup and get the memory cgroup of a container from
> get_exec_env() or get_exec_ub().
> 
> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
> ---
>  include/linux/memcontrol.h |    6 ++++++
>  mm/memcontrol.c            |   31 +++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 5393f5f3b7d5..1382e4939a21 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -127,6 +127,7 @@ extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
>  					struct task_struct *p);
>  extern void mem_cgroup_replace_page_cache(struct page *oldpage,
>  					struct page *newpage);
> +unsigned long mem_cgroup_ram_pages(void);
>  
>  #ifdef CONFIG_MEMCG_SWAP
>  extern int do_swap_account;
> @@ -400,6 +401,11 @@ static inline void mem_cgroup_replace_page_cache(struct page *oldpage,
>  				struct page *newpage)
>  {
>  }
> +
> +static inline unsigned long mem_cgroup_ram_pages(void)
> +{
> +	return ULONG_MAX;
> +}
>  #endif /* CONFIG_MEMCG */
>  
>  #if !defined(CONFIG_MEMCG) || !defined(CONFIG_DEBUG_VM)
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6ef83fbd1a58..d8f9b5561222 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1620,6 +1620,37 @@ void mem_cgroup_note_oom_kill(struct mem_cgroup *root_memcg,
>  		css_put(&memcg_to_put->css);
>  }
>  
> +/*
> + * XXX: This function returns the limit of the topmost memory cgroup the
> + * current process belongs to (ULONG_MAX if unlimited). It is used to get the
> + * number of memory pages available to a Virtuozzo container. Here we
> + * implicitly assume that each container lives in its own top level memory
> + * cgroup. If it is changed, this function must be reworked. E.g. we could
> + * assign a memory cgroup to each ve or beancounter cgroup and get the memory
> + * cgroup of a container from get_exec_env() or get_exec_ub().
> + */
> +unsigned long mem_cgroup_ram_pages(void)
> +{
> +	struct mem_cgroup *memcg_to_put, *memcg, *parent;
> +	unsigned long long limit = RESOURCE_MAX;
> +
> +	memcg_to_put = memcg = try_get_mem_cgroup_from_mm(current->mm);
> +	if (!memcg || memcg == root_mem_cgroup)
> +		goto out;
> +
> +	while ((parent = parent_mem_cgroup(memcg)) &&
> +	       parent != root_mem_cgroup)
> +		memcg = parent;
> +
> +	limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
> +out:
> +	if (memcg_to_put)
> +		css_put(&memcg_to_put->css);
> +	if (limit == RESOURCE_MAX)
> +		return ULONG_MAX;
> +	return min_t(unsigned long long, ULONG_MAX, limit >> PAGE_SHIFT);
> +}
> +
>  #define mem_cgroup_from_res_counter(counter, member)	\
>  	container_of(counter, struct mem_cgroup, member)
>  
>