linux-kernel - Re: [PATCH 1/3] zpool: extend API to match zsmalloc

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Date:   Fri, 18 Oct 2019 07:23:57 -0400
From:   Dan Streetman <ddstreet@...e.org>
To:     Vitaly Wool <vitalywool@...il.com>
Cc:     Linux-MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Shakeel Butt <shakeelb@...gle.com>,
        Henry Burns <henrywolfeburns@...il.com>,
        "Theodore Ts'o" <tytso@...nk.org>
Subject: Re: [PATCH 1/3] zpool: extend API to match zsmalloc

On Thu, Oct 10, 2019 at 4:09 PM Vitaly Wool <vitalywool@...il.com> wrote:
>
> This patch adds the following functions to the zpool API:
> - zpool_compact()
> - zpool_get_num_compacted()
> - zpool_huge_class_size()
>
> The first one triggers compaction for the underlying allocator, the
> second retrieves the number of pages migrated due to compaction for
> the whole time of this pool's existence and the third one returns
> the huge class size.
>
> This API extension is done to align zpool API with zsmalloc API.
>
> Signed-off-by: Vitaly Wool <vitalywool@...il.com>

Seems reasonable to me.

Reviewed-by: Dan Streetman <ddstreet@...e.org>

> ---
>  include/linux/zpool.h | 14 +++++++++++++-
>  mm/zpool.c            | 36 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/zpool.h b/include/linux/zpool.h
> index 51bf43076165..31f0c1360569 100644
> --- a/include/linux/zpool.h
> +++ b/include/linux/zpool.h
> @@ -61,8 +61,13 @@ void *zpool_map_handle(struct zpool *pool, unsigned long handle,
>
>  void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
>
> +unsigned long zpool_compact(struct zpool *pool);
> +
> +unsigned long zpool_get_num_compacted(struct zpool *pool);
> +
>  u64 zpool_get_total_size(struct zpool *pool);
>
> +size_t zpool_huge_class_size(struct zpool *zpool);
>
>  /**
>   * struct zpool_driver - driver implementation for zpool
> @@ -75,7 +80,10 @@ u64 zpool_get_total_size(struct zpool *pool);
>   * @shrink:    shrink the pool.
>   * @map:       map a handle.
>   * @unmap:     unmap a handle.
> - * @total_size:        get total size of a pool.
> + * @compact:   try to run compaction over a pool
> + * @get_num_compacted: get amount of compacted pages for a pool
> + * @total_size:        get total size of a pool
> + * @huge_class_size: huge class threshold for pool pages.
>   *
>   * This is created by a zpool implementation and registered
>   * with zpool.
> @@ -104,7 +112,11 @@ struct zpool_driver {
>                                 enum zpool_mapmode mm);
>         void (*unmap)(void *pool, unsigned long handle);
>
> +       unsigned long (*compact)(void *pool);
> +       unsigned long (*get_num_compacted)(void *pool);
> +
>         u64 (*total_size)(void *pool);
> +       size_t (*huge_class_size)(void *pool);
>  };
>
>  void zpool_register_driver(struct zpool_driver *driver);
> diff --git a/mm/zpool.c b/mm/zpool.c
> index 863669212070..55e69213c2eb 100644
> --- a/mm/zpool.c
> +++ b/mm/zpool.c
> @@ -362,6 +362,30 @@ void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
>         zpool->driver->unmap(zpool->pool, handle);
>  }
>
> + /**
> + * zpool_compact() - try to run compaction over zpool
> + * @pool       The zpool to compact
> + *
> + * Returns: the number of migrated pages
> + */
> +unsigned long zpool_compact(struct zpool *zpool)
> +{
> +       return zpool->driver->compact ? zpool->driver->compact(zpool->pool) : 0;
> +}
> +
> +
> +/**
> + * zpool_get_num_compacted() - get the number of migrated/compacted pages
> + * @pool       The zpool to get compaction statistic for
> + *
> + * Returns: the total number of migrated pages for the pool
> + */
> +unsigned long zpool_get_num_compacted(struct zpool *zpool)
> +{
> +       return zpool->driver->get_num_compacted ?
> +               zpool->driver->get_num_compacted(zpool->pool) : 0;
> +}
> +
>  /**
>   * zpool_get_total_size() - The total size of the pool
>   * @zpool:     The zpool to check
> @@ -375,6 +399,18 @@ u64 zpool_get_total_size(struct zpool *zpool)
>         return zpool->driver->total_size(zpool->pool);
>  }
>
> +/**
> + * zpool_huge_class_size() - get size for the "huge" class
> + * @pool       The zpool to check
> + *
> + * Returns: size of the huge class
> + */
> +size_t zpool_huge_class_size(struct zpool *zpool)
> +{
> +       return zpool->driver->huge_class_size ?
> +               zpool->driver->huge_class_size(zpool->pool) : 0;
> +}
> +
>  /**
>   * zpool_evictable() - Test if zpool is potentially evictable
>   * @zpool:     The zpool to test
> --
> 2.20.1