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Date:	Mon, 29 Dec 2014 21:51:53 +0800
From:	Ganesh Mahendran <opensource.ganesh@...il.com>
To:	Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linux-MM <linux-mm@...ck.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Ganesh Mahendran <opensource.ganesh@...il.com>
Subject: Re: [PATCH V2 2/2] mm/zsmalloc: add statistics support

Sorry, Please ignore this patch.
I miss something.

2014-12-29 20:28 GMT+08:00 Ganesh Mahendran <opensource.ganesh@...il.com>:
> Keeping fragmentation of zsmalloc in a low level is our target. But now
> we still need to add the debug code in zsmalloc to get the quantitative data.
>
> This patch adds a new configuration CONFIG_ZSMALLOC_STAT to enable the
> statistics collection for developers. Currently only the objects statatitics
> in each class are collected. User can get the information via debugfs.
>      cat /sys/kernel/debug/zsmalloc/zram0/...
>
> For example:
>
> After I copied "jdk-8u25-linux-x64.tar.gz" to zram with ext4 filesystem:
>  class  size obj_allocated   obj_used pages_used
>      0    32             0          0          0
>      1    48           256         12          3
>      2    64            64         14          1
>      3    80            51          7          1
>      4    96           128          5          3
>      5   112            73          5          2
>      6   128            32          4          1
>      7   144             0          0          0
>      8   160             0          0          0
>      9   176             0          0          0
>     10   192             0          0          0
>     11   208             0          0          0
>     12   224             0          0          0
>     13   240             0          0          0
>     14   256            16          1          1
>     15   272            15          9          1
>     16   288             0          0          0
>     17   304             0          0          0
>     18   320             0          0          0
>     19   336             0          0          0
>     20   352             0          0          0
>     21   368             0          0          0
>     22   384             0          0          0
>     23   400             0          0          0
>     24   416             0          0          0
>     25   432             0          0          0
>     26   448             0          0          0
>     27   464             0          0          0
>     28   480             0          0          0
>     29   496            33          1          4
>     30   512             0          0          0
>     31   528             0          0          0
>     32   544             0          0          0
>     33   560             0          0          0
>     34   576             0          0          0
>     35   592             0          0          0
>     36   608             0          0          0
>     37   624             0          0          0
>     38   640             0          0          0
>     40   672             0          0          0
>     42   704             0          0          0
>     43   720            17          1          3
>     44   736             0          0          0
>     46   768             0          0          0
>     49   816             0          0          0
>     51   848             0          0          0
>     52   864            14          1          3
>     54   896             0          0          0
>     57   944            13          1          3
>     58   960             0          0          0
>     62  1024             4          1          1
>     66  1088            15          2          4
>     67  1104             0          0          0
>     71  1168             0          0          0
>     74  1216             0          0          0
>     76  1248             0          0          0
>     83  1360             3          1          1
>     91  1488            11          1          4
>     94  1536             0          0          0
>    100  1632             5          1          2
>    107  1744             0          0          0
>    111  1808             9          1          4
>    126  2048             4          4          2
>    144  2336             7          3          4
>    151  2448             0          0          0
>    168  2720            15         15         10
>    190  3072            28         27         21
>    202  3264             0          0          0
>    254  4096         36209      36209      36209
>
>  Total               37022      36326      36288
>
> We can calculate the overall fragentation by the last line:
>     Total               37022      36326      36288
>     (37022 - 36326) / 37022 = 1.87%
>
> Also by analysing objects alocated in every class we know why we got so low fragmentation:
>     Most of the allocated objects is in <class 254>. And there is only 1 page in class
>     254 zspage.  So, No fragmentation will be introduced by allocating objs in class 254.
>
> And in the future, we can collect other zsmalloc statistics as we need and analyse them.
>
> Signed-off-by: Ganesh Mahendran <opensource.ganesh@...il.com>
> Suggested-by: Minchan Kim <minchan@...nel.org>
> Cc: Nitin Gupta <ngupta@...are.org>
> Acked-by: Minchan Kim <minchan@...nel.org>
>
> ---
> Change in V2:
>     use array in struct zs_size_stat -- Minchan
> ---
>  mm/Kconfig    |   10 +++
>  mm/zsmalloc.c |  233 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 239 insertions(+), 4 deletions(-)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 1d1ae6b..95c5728 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -601,6 +601,16 @@ config PGTABLE_MAPPING
>           You can check speed with zsmalloc benchmark:
>           https://github.com/spartacus06/zsmapbench
>
> +config ZSMALLOC_STAT
> +       bool "Export zsmalloc statistics"
> +       depends on ZSMALLOC
> +       select DEBUG_FS
> +       help
> +         This option enables code in the zsmalloc to collect various
> +         statistics about whats happening in zsmalloc and exports that
> +         information to userspace via debugfs.
> +         If unsure, say N.
> +
>  config GENERIC_EARLY_IOREMAP
>         bool
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 2359e61..2d5f5be 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -91,6 +91,7 @@
>  #include <linux/hardirq.h>
>  #include <linux/spinlock.h>
>  #include <linux/types.h>
> +#include <linux/debugfs.h>
>  #include <linux/zsmalloc.h>
>  #include <linux/zpool.h>
>
> @@ -168,6 +169,22 @@ enum fullness_group {
>         ZS_FULL
>  };
>
> +enum zs_stat_type {
> +       OBJ_ALLOCATED,
> +       OBJ_USED,
> +       NR_ZS_STAT_TYPE,
> +};
> +
> +#ifdef CONFIG_ZSMALLOC_STAT
> +
> +static struct dentry *zs_stat_root;
> +
> +struct zs_size_stat {
> +       unsigned long objs[NR_ZS_STAT_TYPE];
> +};
> +
> +#endif
> +
>  /*
>   * number of size_classes
>   */
> @@ -200,6 +217,10 @@ struct size_class {
>         /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
>         int pages_per_zspage;
>
> +#ifdef CONFIG_ZSMALLOC_STAT
> +       struct zs_size_stat stats;
> +#endif
> +
>         spinlock_t lock;
>
>         struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
> @@ -217,10 +238,16 @@ struct link_free {
>  };
>
>  struct zs_pool {
> +       char *name;
> +
>         struct size_class **size_class;
>
>         gfp_t flags;    /* allocation flags used when growing pool */
>         atomic_long_t pages_allocated;
> +
> +#ifdef CONFIG_ZSMALLOC_STAT
> +       struct dentry *stat_dentry;
> +#endif
>  };
>
>  /*
> @@ -942,6 +969,166 @@ static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
>         return true;
>  }
>
> +#ifdef CONFIG_ZSMALLOC_STAT
> +
> +static inline void zs_stat_inc(struct size_class *class,
> +                               enum zs_stat_type type, unsigned long cnt)
> +{
> +       class->stats.objs[type] += cnt;
> +}
> +
> +static inline void zs_stat_dec(struct size_class *class,
> +                               enum zs_stat_type type, unsigned long cnt)
> +{
> +       class->stats.objs[type] -= cnt;
> +}
> +
> +static inline unsigned long zs_stat_get(struct size_class *class,
> +                               enum zs_stat_type type)
> +{
> +       return class->stats.objs[type];
> +}
> +
> +static int __init zs_stat_init(void)
> +{
> +       if (!debugfs_initialized())
> +               return -ENODEV;
> +
> +       zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
> +       if (!zs_stat_root)
> +               return -ENOMEM;
> +
> +       return 0;
> +}
> +
> +static void __exit zs_stat_exit(void)
> +{
> +       debugfs_remove_recursive(zs_stat_root);
> +}
> +
> +static int zs_stats_size_show(struct seq_file *s, void *v)
> +{
> +       int i;
> +       struct zs_pool *pool = s->private;
> +       struct size_class *class;
> +       int objs_per_zspage;
> +       unsigned long obj_allocated, obj_used, pages_used;
> +       unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
> +
> +       seq_printf(s, " %5s %5s %13s %10s %10s\n", "class", "size",
> +                               "obj_allocated", "obj_used", "pages_used");
> +
> +       for (i = 0; i < zs_size_classes; i++) {
> +               class = pool->size_class[i];
> +
> +               if (class->index != i)
> +                       continue;
> +
> +               spin_lock(&class->lock);
> +               obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
> +               obj_used = zs_stat_get(class, OBJ_USED);
> +               spin_unlock(&class->lock);
> +
> +               objs_per_zspage = get_maxobj_per_zspage(class->size,
> +                               class->pages_per_zspage);
> +               pages_used = obj_allocated / objs_per_zspage *
> +                               class->pages_per_zspage;
> +
> +               seq_printf(s, " %5u %5u    %10lu %10lu %10lu\n", i,
> +                       class->size, obj_allocated, obj_used, pages_used);
> +
> +               total_objs += obj_allocated;
> +               total_used_objs += obj_used;
> +               total_pages += pages_used;
> +       }
> +
> +       seq_puts(s, "\n");
> +       seq_printf(s, " %5s %5s    %10lu %10lu %10lu\n", "Total", "",
> +                       total_objs, total_used_objs, total_pages);
> +
> +       return 0;
> +}
> +
> +static int zs_stats_size_open(struct inode *inode, struct file *file)
> +{
> +       return single_open(file, zs_stats_size_show, inode->i_private);
> +}
> +
> +static const struct file_operations zs_stat_size_ops = {
> +       .open           = zs_stats_size_open,
> +       .read           = seq_read,
> +       .llseek         = seq_lseek,
> +       .release        = single_release,
> +};
> +
> +static int zs_pool_stat_create(char *name, struct zs_pool *pool)
> +{
> +       struct dentry *entry;
> +
> +       if (!zs_stat_root)
> +               return -ENODEV;
> +
> +       entry = debugfs_create_dir(name, zs_stat_root);
> +       if (!entry) {
> +               pr_warn("debugfs dir <%s> creation failed\n", name);
> +               return -ENOMEM;
> +       }
> +       pool->stat_dentry = entry;
> +
> +       entry = debugfs_create_file("obj_in_classes", S_IFREG | S_IRUGO,
> +                       pool->stat_dentry, pool, &zs_stat_size_ops);
> +       if (!entry) {
> +               pr_warn("%s: debugfs file entry <%s> creation failed\n",
> +                               name, "obj_in_classes");
> +               return -ENOMEM;
> +       }
> +
> +       return 0;
> +}
> +
> +static void zs_pool_stat_destroy(struct zs_pool *pool)
> +{
> +       debugfs_remove_recursive(pool->stat_dentry);
> +}
> +
> +#else /* CONFIG_ZSMALLOC_STAT */
> +
> +static inline void zs_stat_inc(struct size_class *class,
> +                               enum zs_stat_type type, unsigned long cnt)
> +{
> +}
> +
> +static inline void zs_stat_dec(struct size_class *class,
> +                               enum zs_stat_type type, unsigned long cnt)
> +{
> +}
> +
> +static inline unsigned long zs_stat_get(struct size_class *class,
> +                               enum zs_stat_type type)
> +{
> +       return 0;
> +}
> +
> +static int __init zs_stat_init(void)
> +{
> +       return 0;
> +}
> +
> +static void __exit zs_stat_exit(void)
> +{
> +}
> +
> +static inline int zs_pool_stat_create(struct zs_pool *pool)
> +{
> +       return 0;
> +}
> +
> +static inline void zs_pool_stat_destroy(struct zs_pool *pool)
> +{
> +}
> +
> +#endif
> +
>  unsigned long zs_get_total_pages(struct zs_pool *pool)
>  {
>         return atomic_long_read(&pool->pages_allocated);
> @@ -1074,7 +1261,10 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
>                 set_zspage_mapping(first_page, class->index, ZS_EMPTY);
>                 atomic_long_add(class->pages_per_zspage,
>                                         &pool->pages_allocated);
> +
>                 spin_lock(&class->lock);
> +               zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> +                               class->size, class->pages_per_zspage));
>         }
>
>         obj = (unsigned long)first_page->freelist;
> @@ -1088,6 +1278,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
>         kunmap_atomic(vaddr);
>
>         first_page->inuse++;
> +       zs_stat_inc(class, OBJ_USED, 1);
>         /* Now move the zspage to another fullness group, if required */
>         fix_fullness_group(pool, first_page);
>         spin_unlock(&class->lock);
> @@ -1128,6 +1319,12 @@ void zs_free(struct zs_pool *pool, unsigned long obj)
>
>         first_page->inuse--;
>         fullness = fix_fullness_group(pool, first_page);
> +
> +       zs_stat_dec(class, OBJ_USED, 1);
> +       if (fullness == ZS_EMPTY)
> +               zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
> +                               class->size, class->pages_per_zspage));
> +
>         spin_unlock(&class->lock);
>
>         if (fullness == ZS_EMPTY) {
> @@ -1158,9 +1355,16 @@ struct zs_pool *zs_create_pool(char *name, gfp_t flags)
>         if (!pool)
>                 return NULL;
>
> +       pool->name = kstrdup(name, GFP_KERNEL);
> +       if (!pool->name) {
> +               kfree(pool);
> +               return NULL;
> +       }
> +
>         pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
>                         GFP_KERNEL);
>         if (!pool->size_class) {
> +               kfree(pool->name);
>                 kfree(pool);
>                 return NULL;
>         }
> @@ -1210,6 +1414,9 @@ struct zs_pool *zs_create_pool(char *name, gfp_t flags)
>
>         pool->flags = flags;
>
> +       if (zs_pool_stat_create(name, pool))
> +               goto err;
> +
>         return pool;
>
>  err:
> @@ -1222,6 +1429,8 @@ void zs_destroy_pool(struct zs_pool *pool)
>  {
>         int i;
>
> +       zs_pool_stat_destroy(pool);
> +
>         for (i = 0; i < zs_size_classes; i++) {
>                 int fg;
>                 struct size_class *class = pool->size_class[i];
> @@ -1242,6 +1451,7 @@ void zs_destroy_pool(struct zs_pool *pool)
>         }
>
>         kfree(pool->size_class);
> +       kfree(pool->name);
>         kfree(pool);
>  }
>  EXPORT_SYMBOL_GPL(zs_destroy_pool);
> @@ -1250,17 +1460,30 @@ static int __init zs_init(void)
>  {
>         int ret = zs_register_cpu_notifier();
>
> -       if (ret) {
> -               zs_unregister_cpu_notifier();
> -               return ret;
> -       }
> +       if (ret)
> +               goto notifier_fail;
>
>         init_zs_size_classes();
>
>  #ifdef CONFIG_ZPOOL
>         zpool_register_driver(&zs_zpool_driver);
>  #endif
> +
> +       ret = zs_stat_init();
> +       if (ret) {
> +               pr_err("zs stat initialization failed\n");
> +               goto stat_fail;
> +       }
>         return 0;
> +
> +stat_fail:
> +#ifdef CONFIG_ZPOOL
> +       zpool_unregister_driver(&zs_zpool_driver);
> +#endif
> +notifier_fail:
> +       zs_unregister_cpu_notifier();
> +
> +       return ret;
>  }
>
>  static void __exit zs_exit(void)
> @@ -1269,6 +1492,8 @@ static void __exit zs_exit(void)
>         zpool_unregister_driver(&zs_zpool_driver);
>  #endif
>         zs_unregister_cpu_notifier();
> +
> +       zs_stat_exit();
>  }
>
>  module_init(zs_init);
> --
> 1.7.9.5
>
--
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