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SubjectRe: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure
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On Thu, Mar 4, 2010 at 12:40 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 |   80 ++++++++-
>  mm/memcontrol.c            |  420 +++++++++++++++++++++++++++++++++++++++-----
>  2 files changed, 450 insertions(+), 50 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 1f9b119..cc3421b 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -19,12 +19,66 @@
>
>  #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,
> +};
> +
> +/* Dirty memory parameters */
> +struct dirty_param {
> +       int dirty_ratio;
> +       unsigned long dirty_bytes;
> +       int dirty_background_ratio;
> +       unsigned long dirty_background_bytes;
> +};
> +
> +/*
> + * 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_EVENTS,      /* incremented at every  pagein/pageout */
> +       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,
> +};
> +
> +/*
> + * TODO: provide a validation check routine. And retry if validation
> + * fails.
> + */
> +static inline void get_global_dirty_param(struct dirty_param *param)
> +{
> +       param->dirty_ratio = vm_dirty_ratio;
> +       param->dirty_bytes = vm_dirty_bytes;
> +       param->dirty_background_ratio = dirty_background_ratio;
> +       param->dirty_background_bytes = dirty_background_bytes;
> +}
> +
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR
>  /*
>  * All "charge" functions with gfp_mask should use GFP_KERNEL or
> @@ -117,6 +171,10 @@ extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
>  extern int do_swap_account;
>  #endif
>
> +extern bool mem_cgroup_has_dirty_limit(void);
> +extern void get_dirty_param(struct dirty_param *param);
> +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 +183,8 @@ 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 +359,8 @@ 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 +371,21 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>        return 0;
>  }
>
> +static inline bool mem_cgroup_has_dirty_limit(void)
> +{
> +       return false;
> +}
> +
> +static inline void get_dirty_param(struct dirty_param *param)
> +{
> +       get_global_dirty_param(param);
> +}
> +
> +static inline s64 mem_cgroup_page_stat(enum mem_cgroup_page_stat_item item)
> +{
> +       return -ENOSYS;
> +}
> +
>  #endif /* CONFIG_CGROUP_MEM_CONT */
>
>  #endif /* _LINUX_MEMCONTROL_H */
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 497b6f7..9842e7b 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -73,28 +73,23 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/
>  #define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
>  #define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
>
> -/*
> - * 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_EVENTS,      /* incremented at every  pagein/pageout */
> -
> -       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;
> +};
> +
> +enum {
> +       MEM_CGROUP_DIRTY_RATIO,
> +       MEM_CGROUP_DIRTY_BYTES,
> +       MEM_CGROUP_DIRTY_BACKGROUND_RATIO,
> +       MEM_CGROUP_DIRTY_BACKGROUND_BYTES,
> +};
> +
>  /*
>  * per-zone information in memory controller.
>  */
> @@ -208,6 +203,9 @@ struct mem_cgroup {
>
>        unsigned int    swappiness;
>
> +       /* control memory cgroup dirty pages */
> +       struct dirty_param dirty_param;
> +
>        /* set when res.limit == memsw.limit */
>        bool            memsw_is_minimum;
>
> @@ -1033,6 +1031,156 @@ static unsigned int get_swappiness(struct mem_cgroup *memcg)
>        return swappiness;
>  }
>
> +static bool dirty_param_is_valid(struct dirty_param *param)
> +{
> +       if (param->dirty_ratio && param->dirty_bytes)
> +               return false;
> +       if (param->dirty_background_ratio && param->dirty_background_bytes)
> +               return false;
> +       return true;
> +}
> +
> +static void
> +__mem_cgroup_get_dirty_param(struct dirty_param *param, struct mem_cgroup *mem)
> +{
> +       param->dirty_ratio = mem->dirty_param.dirty_ratio;
> +       param->dirty_bytes = mem->dirty_param.dirty_bytes;
> +       param->dirty_background_ratio = mem->dirty_param.dirty_background_ratio;
> +       param->dirty_background_bytes = mem->dirty_param.dirty_background_bytes;
> +}
> +
> +/*
> + * get_dirty_param() - get dirty memory parameters of the current memcg
> + * @param:     a structure is filled with the dirty memory settings
> + *
> + * The function fills @param with the current memcg dirty memory settings. If
> + * memory cgroup is disabled or in case of error the structure is filled with
> + * the global dirty memory settings.
> + */
> +void get_dirty_param(struct dirty_param *param)
> +{
> +       struct mem_cgroup *memcg;
> +
> +       if (mem_cgroup_disabled()) {
> +               get_global_dirty_param(param);
> +               return;
> +       }
> +       /*
> +        * 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().
> +        */
> +       while (1) {
> +               rcu_read_lock();
> +               memcg = mem_cgroup_from_task(current);
> +               if (likely(memcg))
> +                       __mem_cgroup_get_dirty_param(param, memcg);
> +               else
> +                       get_global_dirty_param(param);
> +               rcu_read_unlock();
> +               /*
> +                * Since global and memcg dirty_param are not protected we try
> +                * to speculatively read them and retry if we get inconsistent
> +                * values.
> +                */
> +               if (likely(dirty_param_is_valid(param)))
> +                       break;
> +       }
> +}
> +
> +static inline bool mem_cgroup_can_swap(struct mem_cgroup *memcg)
> +{
> +       if (!do_swap_account)
> +               return nr_swap_pages > 0;
> +       return !memcg->memsw_is_minimum &&
> +               (res_counter_read_u64(&memcg->memsw, RES_LIMIT) > 0);
> +}
> +
> +static s64 mem_cgroup_get_local_page_stat(struct mem_cgroup *memcg,
> +                               enum mem_cgroup_page_stat_item item)
> +{
> +       s64 ret;
> +
> +       switch (item) {
> +       case MEMCG_NR_DIRTYABLE_PAGES:
> +               ret = res_counter_read_u64(&memcg->res, RES_LIMIT) -
> +                       res_counter_read_u64(&memcg->res, RES_USAGE);
> +               /* Translate free memory in pages */
> +               ret >>= PAGE_SHIFT;
> +               ret += mem_cgroup_read_stat(memcg, LRU_ACTIVE_FILE) +
> +                       mem_cgroup_read_stat(memcg, LRU_INACTIVE_FILE);
> +               if (mem_cgroup_can_swap(memcg))
> +                       ret += mem_cgroup_read_stat(memcg, LRU_ACTIVE_ANON) +
> +                               mem_cgroup_read_stat(memcg, LRU_INACTIVE_ANON);
> +               break;
> +       case MEMCG_NR_RECLAIM_PAGES:
> +               ret = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_FILE_DIRTY) +
> +                       mem_cgroup_read_stat(memcg,
> +                                       MEM_CGROUP_STAT_UNSTABLE_NFS);
> +               break;
> +       case MEMCG_NR_WRITEBACK:
> +               ret = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_WRITEBACK);
> +               break;
> +       case MEMCG_NR_DIRTY_WRITEBACK_PAGES:
> +               ret = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_WRITEBACK) +
> +                       mem_cgroup_read_stat(memcg,
> +                               MEM_CGROUP_STAT_UNSTABLE_NFS);
> +               break;
> +       default:
> +               BUG_ON(1);

Just BUG()?
Andd add 'break;', please.

> +       }
> +       return ret;
> +}
> +
> +static int mem_cgroup_page_stat_cb(struct mem_cgroup *mem, void *data)
> +{
> +       struct mem_cgroup_page_stat *stat = (struct mem_cgroup_page_stat *)data;
> +
> +       stat->value += mem_cgroup_get_local_page_stat(mem, stat->item);
> +       return 0;
> +}
> +
> +/*
> + * mem_cgroup_has_dirty_limit() - check if current memcg has local dirty limits
> + *
> + * Return true if the current memory cgroup has local dirty memory settings,
> + * false otherwise.
> + */
> +bool mem_cgroup_has_dirty_limit(void)
> +{
> +       if (mem_cgroup_disabled())
> +               return false;
> +       return mem_cgroup_from_task(current) != NULL;
> +}
> +
> +/*
> + * mem_cgroup_page_stat() - get memory cgroup file cache statistics
> + * @item:      memory statistic item exported to the kernel
> + *
> + * Return the accounted statistic value, or a negative value in case of error.
> + */
> +s64 mem_cgroup_page_stat(enum mem_cgroup_page_stat_item item)
> +{
> +       struct mem_cgroup_page_stat stat = {};
> +       struct mem_cgroup *memcg;
> +
> +       rcu_read_lock();
> +       memcg = mem_cgroup_from_task(current);
> +       if (memcg) {
> +               /*
> +                * Recursively evaulate page statistics against all cgroup
> +                * under hierarchy tree
> +                */
> +               stat.item = item;
> +               mem_cgroup_walk_tree(memcg, &stat, mem_cgroup_page_stat_cb);
> +       } else
> +               stat.value = -EINVAL;
> +       rcu_read_unlock();
> +
> +       return stat.value;
> +}
> +
>  static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
>  {
>        int *val = data;
> @@ -1275,34 +1423,70 @@ static void record_last_oom(struct mem_cgroup *mem)
>  }
>
>  /*
> - * Currently used to update mapped file statistics, but the routine can be
> - * generalized to update other statistics as well.
> + * Generalized routine to update file cache's status for memcg.
> + *
> + * Before calling this, mapping->tree_lock should be held and preemption is
> + * disabled.  Then, it's guarnteed that the page is not uncharged while we
> + * access page_cgroup. We can make use of that.
>  */
> -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)
>  {
>        struct mem_cgroup *mem;
>        struct page_cgroup *pc;
>
> +       if (mem_cgroup_disabled())
> +               return;
>        pc = lookup_page_cgroup(page);
> -       if (unlikely(!pc))
> +       if (unlikely(!pc) || !PageCgroupUsed(pc))
>                return;
>
> -       lock_page_cgroup(pc);
> -       mem = pc->mem_cgroup;
> -       if (!mem)
> -               goto done;
> -
> -       if (!PageCgroupUsed(pc))
> -               goto done;
> -
> +       lock_page_cgroup_migrate(pc);
>        /*
> -        * Preemption is already disabled. We can use __this_cpu_xxx
> -        */
> -       __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED], val);
> -
> -done:
> -       unlock_page_cgroup(pc);
> +       * It's guarnteed that this page is never uncharged.
> +       * The only racy problem is moving account among memcgs.
> +       */
> +       switch (idx) {
> +       case MEM_CGROUP_STAT_FILE_MAPPED:
> +               if (val > 0)
> +                       SetPageCgroupFileMapped(pc);
> +               else
> +                       ClearPageCgroupFileMapped(pc);
> +               break;
> +       case MEM_CGROUP_STAT_FILE_DIRTY:
> +               if (val > 0)
> +                       SetPageCgroupDirty(pc);
> +               else
> +                       ClearPageCgroupDirty(pc);
> +               break;
> +       case MEM_CGROUP_STAT_WRITEBACK:
> +               if (val > 0)
> +                       SetPageCgroupWriteback(pc);
> +               else
> +                       ClearPageCgroupWriteback(pc);
> +               break;
> +       case MEM_CGROUP_STAT_WRITEBACK_TEMP:
> +               if (val > 0)
> +                       SetPageCgroupWritebackTemp(pc);
> +               else
> +                       ClearPageCgroupWritebackTemp(pc);
> +               break;
> +       case MEM_CGROUP_STAT_UNSTABLE_NFS:
> +               if (val > 0)
> +                       SetPageCgroupUnstableNFS(pc);
> +               else
> +                       ClearPageCgroupUnstableNFS(pc);
> +               break;
> +       default:
> +               BUG();
> +               break;
> +       }
> +       mem = pc->mem_cgroup;
> +       if (likely(mem))
> +               __this_cpu_add(mem->stat->count[idx], val);
> +       unlock_page_cgroup_migrate(pc);
>  }
> +EXPORT_SYMBOL_GPL(mem_cgroup_update_stat);
>
>  /*
>  * size of first charge trial. "32" comes from vmscan.c's magic value.
> @@ -1701,6 +1885,45 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
>        memcg_check_events(mem, pc->page);
>  }
>
> +/*
> + * Update file cache accounted statistics on task migration.
> + *
> + * TODO: We don't move charges of file (including shmem/tmpfs) pages for now.
> + * So, at the moment this function simply returns without updating accounted
> + * statistics, because we deal only with anonymous pages here.
> + */
> +static void __mem_cgroup_update_file_stat(struct page_cgroup *pc,
> +       struct mem_cgroup *from, struct mem_cgroup *to)
> +{
> +       struct page *page = pc->page;
> +
> +       if (!page_mapped(page) || PageAnon(page))
> +               return;
> +
> +       if (PageCgroupFileMapped(pc)) {
> +               __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
> +               __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
> +       }
> +       if (PageCgroupDirty(pc)) {
> +               __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_DIRTY]);
> +               __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_DIRTY]);
> +       }
> +       if (PageCgroupWriteback(pc)) {
> +               __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_WRITEBACK]);
> +               __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_WRITEBACK]);
> +       }
> +       if (PageCgroupWritebackTemp(pc)) {
> +               __this_cpu_dec(
> +                       from->stat->count[MEM_CGROUP_STAT_WRITEBACK_TEMP]);
> +               __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_WRITEBACK_TEMP]);
> +       }
> +       if (PageCgroupUnstableNFS(pc)) {
> +               __this_cpu_dec(
> +                       from->stat->count[MEM_CGROUP_STAT_UNSTABLE_NFS]);
> +               __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_UNSTABLE_NFS]);
> +       }
> +}
> +
>  /**
>  * __mem_cgroup_move_account - move account of the page
>  * @pc:        page_cgroup of the page.
> @@ -1721,22 +1944,16 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
>  static void __mem_cgroup_move_account(struct page_cgroup *pc,
>        struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)
>  {
> -       struct page *page;
> -
>        VM_BUG_ON(from == to);
>        VM_BUG_ON(PageLRU(pc->page));
>        VM_BUG_ON(!PageCgroupLocked(pc));
>        VM_BUG_ON(!PageCgroupUsed(pc));
>        VM_BUG_ON(pc->mem_cgroup != from);
>
> -       page = pc->page;
> -       if (page_mapped(page) && !PageAnon(page)) {
> -               /* Update mapped_file data for mem_cgroup */
> -               preempt_disable();
> -               __this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
> -               __this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
> -               preempt_enable();
> -       }
> +       preempt_disable();
> +       lock_page_cgroup_migrate(pc);
> +       __mem_cgroup_update_file_stat(pc, from, to);
> +
>        mem_cgroup_charge_statistics(from, pc, false);
>        if (uncharge)
>                /* This is not "cancel", but cancel_charge does all we need. */
> @@ -1745,6 +1962,8 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc,
>        /* caller should have done css_get */
>        pc->mem_cgroup = to;
>        mem_cgroup_charge_statistics(to, pc, true);
> +       unlock_page_cgroup_migrate(pc);
> +       preempt_enable();
>        /*
>         * We charges against "to" which may not have any tasks. Then, "to"
>         * can be under rmdir(). But in current implementation, caller of
> @@ -3042,6 +3261,10 @@ enum {
>        MCS_PGPGIN,
>        MCS_PGPGOUT,
>        MCS_SWAP,
> +       MCS_FILE_DIRTY,
> +       MCS_WRITEBACK,
> +       MCS_WRITEBACK_TEMP,
> +       MCS_UNSTABLE_NFS,
>        MCS_INACTIVE_ANON,
>        MCS_ACTIVE_ANON,
>        MCS_INACTIVE_FILE,
> @@ -3064,6 +3287,10 @@ struct {
>        {"pgpgin", "total_pgpgin"},
>        {"pgpgout", "total_pgpgout"},
>        {"swap", "total_swap"},
> +       {"filedirty", "dirty_pages"},
> +       {"writeback", "writeback_pages"},
> +       {"writeback_tmp", "writeback_temp_pages"},
> +       {"nfs", "nfs_unstable"},
>        {"inactive_anon", "total_inactive_anon"},
>        {"active_anon", "total_active_anon"},
>        {"inactive_file", "total_inactive_file"},
> @@ -3092,6 +3319,14 @@ static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
>                val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
>                s->stat[MCS_SWAP] += val * PAGE_SIZE;
>        }
> +       val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_DIRTY);
> +       s->stat[MCS_FILE_DIRTY] += val;
> +       val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_WRITEBACK);
> +       s->stat[MCS_WRITEBACK] += val;
> +       val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_WRITEBACK_TEMP);
> +       s->stat[MCS_WRITEBACK_TEMP] += val;
> +       val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_UNSTABLE_NFS);
> +       s->stat[MCS_UNSTABLE_NFS] += val;
>
>        /* per zone stat */
>        val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
> @@ -3453,6 +3688,60 @@ unlock:
>        return ret;
>  }
>
> +static u64 mem_cgroup_dirty_read(struct cgroup *cgrp, struct cftype *cft)
> +{
> +       struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +
> +       switch (cft->private) {
> +       case MEM_CGROUP_DIRTY_RATIO:
> +               return memcg->dirty_param.dirty_ratio;
> +       case MEM_CGROUP_DIRTY_BYTES:
> +               return memcg->dirty_param.dirty_bytes;
> +       case MEM_CGROUP_DIRTY_BACKGROUND_RATIO:
> +               return memcg->dirty_param.dirty_background_ratio;
> +       case MEM_CGROUP_DIRTY_BACKGROUND_BYTES:
> +               return memcg->dirty_param.dirty_background_bytes;
> +       default:
> +               BUG();
> +       }
> +}
> +
> +static int
> +mem_cgroup_dirty_write(struct cgroup *cgrp, struct cftype *cft, u64 val)
> +{
> +       struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +       int type = cft->private;
> +
> +       if (cgrp->parent == NULL)
> +               return -EINVAL;
> +       if ((type == MEM_CGROUP_DIRTY_RATIO ||
> +               type == MEM_CGROUP_DIRTY_BACKGROUND_RATIO) && val > 100)
> +               return -EINVAL;
> +       /*
> +        * TODO: provide a validation check routine. And retry if validation
> +        * fails.
> +        */
> +       switch (type) {
> +       case MEM_CGROUP_DIRTY_RATIO:
> +               memcg->dirty_param.dirty_ratio = val;
> +               memcg->dirty_param.dirty_bytes = 0;
> +               break;
> +       case MEM_CGROUP_DIRTY_BYTES:
> +               memcg->dirty_param.dirty_ratio  = 0;
> +               memcg->dirty_param.dirty_bytes = val;
> +               break;
> +       case MEM_CGROUP_DIRTY_BACKGROUND_RATIO:
> +               memcg->dirty_param.dirty_background_ratio = val;
> +               memcg->dirty_param.dirty_background_bytes = 0;
> +               break;
> +       case MEM_CGROUP_DIRTY_BACKGROUND_BYTES:
> +               memcg->dirty_param.dirty_background_ratio = 0;
> +               memcg->dirty_param.dirty_background_bytes = val;
> +               break;

default:
BUG();
break;

> +       }
> +       return 0;
> +}
> +
>  static struct cftype mem_cgroup_files[] = {
>        {
>                .name = "usage_in_bytes",
> @@ -3504,6 +3793,30 @@ static struct cftype mem_cgroup_files[] = {
>                .write_u64 = mem_cgroup_swappiness_write,
>        },
>        {
> +               .name = "dirty_ratio",
> +               .read_u64 = mem_cgroup_dirty_read,
> +               .write_u64 = mem_cgroup_dirty_write,
> +               .private = MEM_CGROUP_DIRTY_RATIO,
> +       },
> +       {
> +               .name = "dirty_bytes",
> +               .read_u64 = mem_cgroup_dirty_read,
> +               .write_u64 = mem_cgroup_dirty_write,
> +               .private = MEM_CGROUP_DIRTY_BYTES,
> +       },
> +       {
> +               .name = "dirty_background_ratio",
> +               .read_u64 = mem_cgroup_dirty_read,
> +               .write_u64 = mem_cgroup_dirty_write,
> +               .private = MEM_CGROUP_DIRTY_BACKGROUND_RATIO,
> +       },
> +       {
> +               .name = "dirty_background_bytes",
> +               .read_u64 = mem_cgroup_dirty_read,
> +               .write_u64 = mem_cgroup_dirty_write,
> +               .private = MEM_CGROUP_DIRTY_BACKGROUND_BYTES,
> +       },
> +       {
>                .name = "move_charge_at_immigrate",
>                .read_u64 = mem_cgroup_move_charge_read,
>                .write_u64 = mem_cgroup_move_charge_write,
> @@ -3762,8 +4075,21 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
>        mem->last_scanned_child = 0;
>        spin_lock_init(&mem->reclaim_param_lock);
>
> -       if (parent)
> +       if (parent) {
>                mem->swappiness = get_swappiness(parent);
> +               mem->dirty_param = parent->dirty_param;
> +       } else {
> +               while (1) {
> +                       get_global_dirty_param(&mem->dirty_param);
> +                       /*
> +                        * Since global dirty parameters are not protected we
> +                        * try to speculatively read them and retry if we get
> +                        * inconsistent values.
> +                        */
> +                       if (likely(dirty_param_is_valid(&mem->dirty_param)))
> +                               break;
> +               }
> +       }
>        atomic_set(&mem->refcnt, 1);
>        mem->move_charge_at_immigrate = 0;
>        mutex_init(&mem->thresholds_lock);
> --
> 1.6.3.3
>
> --
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