Re: [PATCH -mmotm 2/3] memcg: dirty pages accounting and limiting infrastructure

[Greg Thelen <gthelen@google.com>]

Comments below.  Yet to be tested on my end, but I will test it.

On Mon, Mar 1, 2010 at 1:23 PM, Andrea Righi <arighi@develer.com> wrote:
> Infrastructure to account dirty pages per cgroup and add dirty limit
> interfaces in the cgroupfs:
>
>  - Direct write-out: memory.dirty_ratio, memory.dirty_bytes
>
>  - Background write-out: memory.dirty_background_ratio, memory.dirty_background_bytes
>
> Signed-off-by: Andrea Righi <arighi@develer.com>
> ---
>  include/linux/memcontrol.h |   77 ++++++++++-
>  mm/memcontrol.c            |  336 ++++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 384 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 1f9b119..cc88b2e 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -19,12 +19,50 @@
>
>  #ifndef _LINUX_MEMCONTROL_H
>  #define _LINUX_MEMCONTROL_H
> +
> +#include <linux/writeback.h>
>  #include <linux/cgroup.h>
> +
>  struct mem_cgroup;
>  struct page_cgroup;
>  struct page;
>  struct mm_struct;
>
> +/* Cgroup memory statistics items exported to the kernel */
> +enum mem_cgroup_page_stat_item {
> +       MEMCG_NR_DIRTYABLE_PAGES,
> +       MEMCG_NR_RECLAIM_PAGES,
> +       MEMCG_NR_WRITEBACK,
> +       MEMCG_NR_DIRTY_WRITEBACK_PAGES,
> +};
> +
> +/*
> + * Statistics for memory cgroup.
> + */
> +enum mem_cgroup_stat_index {
> +       /*
> +        * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
> +        */
> +       MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
> +       MEM_CGROUP_STAT_RSS,       /* # of pages charged as anon rss */
> +       MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
> +       MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
> +       MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
> +       MEM_CGROUP_STAT_EVENTS, /* sum of pagein + pageout for internal use */
> +       MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
> +       MEM_CGROUP_STAT_SOFTLIMIT, /* decrements on each page in/out.
> +                                       used by soft limit implementation */
> +       MEM_CGROUP_STAT_THRESHOLDS, /* decrements on each page in/out.
> +                                       used by threshold implementation */
> +       MEM_CGROUP_STAT_FILE_DIRTY,   /* # of dirty pages in page cache */
> +       MEM_CGROUP_STAT_WRITEBACK,   /* # of pages under writeback */
> +       MEM_CGROUP_STAT_WRITEBACK_TEMP,   /* # of pages under writeback using
> +                                               temporary buffers */
> +       MEM_CGROUP_STAT_UNSTABLE_NFS,   /* # of NFS unstable pages */
> +
> +       MEM_CGROUP_STAT_NSTATS,
> +};
> +
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR
>  /*
>  * All "charge" functions with gfp_mask should use GFP_KERNEL or
> @@ -117,6 +155,13 @@ extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
>  extern int do_swap_account;
>  #endif
>
> +extern long mem_cgroup_dirty_ratio(void);
> +extern unsigned long mem_cgroup_dirty_bytes(void);
> +extern long mem_cgroup_dirty_background_ratio(void);
> +extern unsigned long mem_cgroup_dirty_background_bytes(void);
> +
> +extern s64 mem_cgroup_page_stat(enum mem_cgroup_page_stat_item item);
> +
>  static inline bool mem_cgroup_disabled(void)
>  {
>        if (mem_cgroup_subsys.disabled)
> @@ -125,7 +170,8 @@ static inline bool mem_cgroup_disabled(void)
>  }
>
>  extern bool mem_cgroup_oom_called(struct task_struct *task);
> -void mem_cgroup_update_file_mapped(struct page *page, int val);
> +void mem_cgroup_update_stat(struct page *page,
> +                       enum mem_cgroup_stat_index idx, int val);
>  unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>                                                gfp_t gfp_mask, int nid,
>                                                int zid);
> @@ -300,8 +346,8 @@ mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
>  {
>  }
>
> -static inline void mem_cgroup_update_file_mapped(struct page *page,
> -                                                       int val)
> +static inline void mem_cgroup_update_stat(struct page *page,
> +                       enum mem_cgroup_stat_index idx, int val)
>  {
>  }
>
> @@ -312,6 +358,31 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>        return 0;
>  }
>
> +static inline long mem_cgroup_dirty_ratio(void)
> +{
> +       return vm_dirty_ratio;
> +}
> +
> +static inline unsigned long mem_cgroup_dirty_bytes(void)
> +{
> +       return vm_dirty_bytes;
> +}
> +
> +static inline long mem_cgroup_dirty_background_ratio(void)
> +{
> +       return dirty_background_ratio;
> +}
> +
> +static inline unsigned long mem_cgroup_dirty_background_bytes(void)
> +{
> +       return dirty_background_bytes;
> +}
> +
> +static inline s64 mem_cgroup_page_stat(enum mem_cgroup_page_stat_item item)
> +{
> +       return -ENOMEM;
> +}
> +
>  #endif /* CONFIG_CGROUP_MEM_CONT */
>
>  #endif /* _LINUX_MEMCONTROL_H */
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index a443c30..e74cf66 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -66,31 +66,16 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/
>  #define SOFTLIMIT_EVENTS_THRESH (1000)
>  #define THRESHOLDS_EVENTS_THRESH (100)
>
> -/*
> - * Statistics for memory cgroup.
> - */
> -enum mem_cgroup_stat_index {
> -       /*
> -        * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
> -        */
> -       MEM_CGROUP_STAT_CACHE,     /* # of pages charged as cache */
> -       MEM_CGROUP_STAT_RSS,       /* # of pages charged as anon rss */
> -       MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
> -       MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
> -       MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
> -       MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
> -       MEM_CGROUP_STAT_SOFTLIMIT, /* decrements on each page in/out.
> -                                       used by soft limit implementation */
> -       MEM_CGROUP_STAT_THRESHOLDS, /* decrements on each page in/out.
> -                                       used by threshold implementation */
> -
> -       MEM_CGROUP_STAT_NSTATS,
> -};
> -
>  struct mem_cgroup_stat_cpu {
>        s64 count[MEM_CGROUP_STAT_NSTATS];
>  };
>
> +/* Per cgroup page statistics */
> +struct mem_cgroup_page_stat {
> +       enum mem_cgroup_page_stat_item item;
> +       s64 value;
> +};
> +
>  /*
>  * per-zone information in memory controller.
>  */
> @@ -157,6 +142,15 @@ struct mem_cgroup_threshold_ary {
>  static bool mem_cgroup_threshold_check(struct mem_cgroup *mem);
>  static void mem_cgroup_threshold(struct mem_cgroup *mem);
>
> +enum mem_cgroup_dirty_param {
> +       MEM_CGROUP_DIRTY_RATIO,
> +       MEM_CGROUP_DIRTY_BYTES,
> +       MEM_CGROUP_DIRTY_BACKGROUND_RATIO,
> +       MEM_CGROUP_DIRTY_BACKGROUND_BYTES,
> +
> +       MEM_CGROUP_DIRTY_NPARAMS,
> +};
> +
>  /*
>  * The memory controller data structure. The memory controller controls both
>  * page cache and RSS per cgroup. We would eventually like to provide
> @@ -205,6 +199,9 @@ struct mem_cgroup {
>
>        unsigned int    swappiness;
>
> +       /* control memory cgroup dirty pages */
> +       unsigned long dirty_param[MEM_CGROUP_DIRTY_NPARAMS];
> +
>        /* set when res.limit == memsw.limit */
>        bool            memsw_is_minimum;
>
> @@ -1021,6 +1018,164 @@ static unsigned int get_swappiness(struct mem_cgroup *memcg)
>        return swappiness;
>  }
>
> +static unsigned long get_dirty_param(struct mem_cgroup *memcg,
> +                       enum mem_cgroup_dirty_param idx)
> +{
> +       unsigned long ret;
> +
> +       VM_BUG_ON(idx >= MEM_CGROUP_DIRTY_NPARAMS);
> +       spin_lock(&memcg->reclaim_param_lock);
> +       ret = memcg->dirty_param[idx];
> +       spin_unlock(&memcg->reclaim_param_lock);
> +
> +       return ret;
> +}
> +

> +long mem_cgroup_dirty_ratio(void)
> +{
> +       struct mem_cgroup *memcg;
> +       long ret = vm_dirty_ratio;
> +
> +       if (mem_cgroup_disabled())
> +               return ret;
> +       /*
> +        * It's possible that "current" may be moved to other cgroup while we
> +        * access cgroup. But precise check is meaningless because the task can
> +        * be moved after our access and writeback tends to take long time.
> +        * At least, "memcg" will not be freed under rcu_read_lock().
> +        */
> +       rcu_read_lock();
> +       memcg = mem_cgroup_from_task(current);
> +       if (likely(memcg))
> +               ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_RATIO);
> +       rcu_read_unlock();
> +
> +       return ret;
> +}
> +
> +unsigned long mem_cgroup_dirty_bytes(void)
> +{
> +       struct mem_cgroup *memcg;
> +       unsigned long ret = vm_dirty_bytes;
> +
> +       if (mem_cgroup_disabled())
> +               return ret;
> +       rcu_read_lock();
> +       memcg = mem_cgroup_from_task(current);
> +       if (likely(memcg))
> +               ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_BYTES);
> +       rcu_read_unlock();
> +
> +       return ret;
> +}
> +
> +long mem_cgroup_dirty_background_ratio(void)
> +{
> +       struct mem_cgroup *memcg;
> +       long ret = dirty_background_ratio;
> +
> +       if (mem_cgroup_disabled())
> +               return ret;
> +       rcu_read_lock();
> +       memcg = mem_cgroup_from_task(current);
> +       if (likely(memcg))
> +               ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_BACKGROUND_RATIO);
> +       rcu_read_unlock();
> +
> +       return ret;
> +}
> +
> +unsigned long mem_cgroup_dirty_background_bytes(void)
> +{
> +       struct mem_cgroup *memcg;
> +       unsigned long ret = dirty_background_bytes;
> +
> +       if (mem_cgroup_disabled())
> +               return ret;
> +       rcu_read_lock();
> +       memcg = mem_cgroup_from_task(current);
> +       if (likely(memcg))
> +               ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_BACKGROUND_BYTES);
> +       rcu_read_unlock();
> +
> +       return ret;
> +}

Given that mem_cgroup_dirty_[background_]{ratio,bytes}() are similar,
should we refactor the majority of them into a single routine?

--
Greg

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>